• Choose a post by category or constellation

  • Learn the Night Sky

  • Search strategies

    Use the Search box below to find doubles by popular name, RA, or telescope size. For example, a search on "15h" will find all doubles we've reported on that have an RA of 15 hours. A search for "60mm" will find all doubles where we used that size telescope.

Splitting stars – for us and for you!

We are experienced amateur astronomers who especially enjoy viewing double stars with long-focus refractors.  This journal is a record of our observations, but we also hope it will serve as a guide to you to help you plan observing sessions and choose double stars you want to observe.  In the column to the left you’ll find a drop down menu listing the doubles in this blog by constellation – and to the right there’s a list of our 10 most recent observations. Finally, you have two other choices:

  • First, you can read  our observations of a double and leave your own observations of that same star as a comment.
  • Second, you can subscribe to this blog so that you get email notifications when we add a star to it. Just check out the links in the right-hand column.

We’d love to hear from you regarding your own observations of the same doubles.

A West Orion Odyssey: WEB 3, ARN 63, HJ 698, Σ 700, and HJ 697

Mysteries abound in the universe, many of them obscure and many of them subtle, and many more mind boggling beyond belief —– and then there are others that leave you shaking your head and wondering how something so obvious could have been missed so completely. To be less obscure and more direct, how do two eye-catching, very distinctive triple stars sitting five and nine arc minutes from an F.G.W Struve discovery, and twice that distance from a much fainter John Herschel discovery, end up being ignored by both of those observers? And to compound the perplexity, once both of these distinctive triple stars achieves recognition, each is cataloged as a double star. What goes on in this deep dark sector of the sky? Only the sky gods know —– and they’re not talking.

At any rate, mystifying as that situation is, it’s also very mesmerizing.  Would you believe four double and/or triples stars all within a single field of view? In fact, the farthest distance between them amounts to a mere seventeen minutes of arc.

And as long as we’re straining credulity to the breaking point, we may as well wander another one and half degrees south of that quadruple collection of multiple stars to another double star with a more – pardon the phrase – companionable mystery.

First, let’s look at the wide view in order to get ourselves oriented:

Our Orion Odyssey begins just a few degrees west of Mintaka, also known as Delta (δ) Orionis, in the area within the turquoise circle.   (Stellarium screen image with labels added, click on the chart to enlarge it).

Our Orion Odyssey begins just a few degrees west of Mintaka, also known as Delta (δ) Orionis, in the area captured within the turquoise circle. (Stellarium screen image with labels added, click on the chart to enlarge it).

And then let’s close in on our targets:

Starting at Mintaka, we’ll move northwest a distance of 40 arc minutes to 6.87 magnitude HIP 25727, then continue northwest for a full degree to 6.16 magnitude HIP 25378, and then make one more northwest leap for a distance of 52 arc minutes to reach 7.6 magnitude Σ 700. (Stellarium screen image with labels added, click to a larger view).

Starting at Mintaka, we’ll move northwest a distance of 40 arc minutes to 6.87 magnitude HIP 25727, then continue northwest for a full degree to 6.16 magnitude HIP 25378, and then make one more northwest leap for a distance of 52 arc minutes to reach 7.6 magnitude Σ 700. (Stellarium screen image with labels added, click to a larger view).

Center Σ 700 in your eyepiece at a moderate magnification, say 50x to 75x, and you’ll find a dazzling field of subdued starlight that includes these four stars:

WEB 3      No HIP number     SAO: 112705        ARN 63      HIP: 25179   SAO: 112707
RA: 05h 23.1m   Dec: +01° 17’                             RA: 05h 23.2m   Dec: +01° 08’
Magnitudes: 7.29, 10.45                                        Magnitudes: 7.97, 10.1
Separation:  62.2”                                                   Separation:  39.5”
Position Angle: 10°  (WDS 2003)                         Position Angle: 65°  (WDS 2003)
Distance: ?????                                                      Distance: 830 Light Years
Spectral Classifications: K2 and F                      Spectral Classifications: B6 and A2

Σ 700  (H I 75)    HIP: 25174   SAO: 112704        HJ 698       No HIP No.    SAO: 112688
RA: 05h 23.1m   Dec: +01° 03                               RA: 05h 22.4m   Dec: +01° 04’
Magnitudes: 7.69, 7.89                                           Magnitudes: 10.24, 13.0
Separation:  4.9”                                                      Separation:  14.2”
Position Angle: 6°  (WDS 2011)                            Position Angle: 243°  (WDS 2000)
Distance: 750 Light Years                                      Distance: ?????
Spectral Classifications: B9, B9.5                        Spectral Classification: F0
Note:  STF 700 is also known as V1804,            Note: Simbad has B at a mag. of 12.4
an Algol type eclipsing variable with a
period of 2.222878 days.

And since you can’t tell the players without a scorecard, here’s a labeled sketch of the area (there’s an unlabeled version at the end of this post, also):

Σ 700 is the dominant multiple star in this field because of its brightness relative to the other multiple stars, but ARN 63 and WEB 3 are pretty distinctive, too, even at 67x.   If any of the four multiple stars was likely to have been missed, it would be the much dimmer and difficult to separate HJ 698. White, by the way, was the only color visible, except for the very slight reddish-orange tint of WEB 3’s 7.29 magnitude primary.   (East & west reversed to match the refractor view, click on the sketch for a much better view).

Σ 700 is the dominant multiple star in this field because of its brightness relative to the other multiple stars, but ARN 63 and WEB 3 are pretty distinctive, too, even at 67x. If any of the four multiple stars was likely to have been missed, it would be the much dimmer and difficult to separate HJ 698. White, by the way, was the only color visible, except for the very slight reddish-orange tint of WEB 3’s 7.29 magnitude primary. (East & west reversed to match the refractor view, click on the sketch for a much better view).

I was wrestling with another night of poor seeing and murky skies, so the 100x I used for the inset at the right of the sketch was about as high as I could go and still maintain something resembling a focused image. Even at the 67x used for the main sketch, Σ 700 was a shaky sight, but nevertheless it was clearly elongated at that magnification. HJ 698 was also a struggle, thanks to the 2.76 magnitudes of difference between them – although I should point out Simbad lists the secondary at a magnitude of 12.4 (versus the 13.0 in the WDS), which is enough of a difference to provide some advantage given the observing conditions.

Click on the image to enlarge it.

Click on the image to enlarge it.

On the other hand, ARN 63 and WEB 3 were pure visual simplicity itself. At the low magnification I was using, I found both far more visually appealing than Σ 700 and HJ 698. If I had been looking through a telescope with either F.G.W. Struve or John Herschel in 1827, the year each of them made their measurements of the two stars with their initials attached (the senior Struve’s observation is shown at the right, J. Herschel’s is located further down the page), my eye would have been drawn north to both ARN 63 and WEB 3.  Surprisingly, though, WEB 3 didn’t receive measured attention until sometime in the last half of the 19th century (there’s another mystery here: the Reverend T.W. Webb died in 1885, but the first measure for WEB 3 listed in the WDS is dated 1909). ARN 63, on the other hand, wasn’t measured until 2003.

Apart from the fact that ARN 63 and WEB 3 were ignored by both Struve and Herschel, there are two other puzzling mysteries. One is the fact that both stars impress one as possible triple stars on first sight, and the other has to do with the 1892 date of first measurement listed in the WDS for ARN 63.

First, I should point out that it was common for many of the earlier double star observers to establish a limit for separations between components, meaning anything beyond their self-imposed limit was usually ignored. R.G. Aitken wrote an article in 1910 stating Struve’s limit was 32”, which would explain why he passed on both ARN 63 and WEB 3.   I’ve never come across any mention of what separation limit Sir John Herschel employed, but his catalogs do contain a few stars wider than both ARN 63 and WEB 3, although they’re comparatively rare (examples are HJ 980, which he measured at 70” in 1827; and HJ 1079, which he measured at 60” in 1828).

That leaves the triple aspect of ARN 63 and WEB 3 unexplained.   Again, it could be a case of the third stars exceeding the separation limits employed by the observers who first measured these two stars, although I’ve come across numerous cases of companions exceeding the distances of the third star of each of these pairs. What’s clear, however, is there never was – and still isn’t — any standardized separation limit in use from one observer to the next. Nevertheless, it would seem to make sense to extend measures to these third companions in order to provide an initial base for comparing later measurements in an effort to determine whether an orbital relation exists.

And then that leaves us with that 1892 date of first measurement in the WDS for ARN 63. When I first saw that, I assumed someone discovered and measured the star that year.   But as I looked into it further, I found the ARN of ARN 63 belongs to Dave Arnold, who was credited with being the first to measure the star in 2003. That raised the question of why a star with a first measurement date of 1892 would be assigned an identifying prefix in 2003, so I began a long search through the old star catalogs I’ve collected over the years in hopes of finding the name associated with the 1892 date – and kept running into one dead end after another.

My next step was to send an email to Dave Arnold, who graciously replied that as he measured known double stars and came across pairs he was unable to identify, he submitted them to Brian Mason at the US Naval Observatory (USNO) to determine if they had previously been measured. If not, or in a case where measures existed but no credit had ever been assigned, Brian applied the ARN prefix to the star.  Dave suggested I get in touch with Brian to see what information he had.

I had already been in touch with Brian to get the observational data for ARN 63, which also showed measurements of that pair of stars had been made in 1909, 1910, 1929, 1963, 1982, 1991, and 2000. So I contacted Brian again, asking especially about the first three dates, which I had also researched and drawn blanks on.  And at that point I learned something new and very impressive.

All of the measures for the dates prior to 2003 were determined by matching data from various astrometric catalogs kept at the U.S. Naval Observatory in Washington, D.C., which is the home of the Washington Double Star Catalog (WDS).   In other words, using their collection of catalogs, it was possible to determine position angles and separations all the way back to 1892. I’ve always had an immense amount of respect for the resources provided by the WDS, but that additional insight into the capabilities available to the USNO confirms what a priceless resource it is.

Now, on to HJ 697, which lies a short one and a half degrees south of Σ 700. Going back to our second chart again (click here to open it in a second window), with Σ 700 centered in an 8×50 finder, you should be able to catch sight of 4.74 magnitude 22 Orionis, hugged closely by HJ 697. You can also use 6.16 magnitude HIP 25378 and 5.70 magnitude HIP 25223 as visual stepping stones to navigate to it.

HJ 697           HIP: 25028   SAO: 132024
RA: 05h 21.5m   Dec: -00° 25’
Magnitudes   AB: 5.68, 13.05    AC: 5.68, 11.88
Separations  AB: 33.10”             AC: 42.30”
Position Angles   AB: 66° (WDS 2000)    AC: 118° (WDS 2000)
Distance: 1077 Light Years
Spectral Classification:  “A” is B3, “B” is G1, “C” is G3
Notes: “B” had been classified as optical.

 Both the primary of HJ 697 and 22 Orionis are white, and I found a surplus of glowing photons around both stars at 200x. “B” and “C” are easily seen, and if you look carefully, you’ll see another faint star at the southern edge of the primary.   What the heck is that??? (East & west reversed to match the refractor view, click on the sketch to improve the view).

Both the primary of HJ 697 and 22 Orionis are white, and I found a surplus of glowing photons around both stars at 200x. “B” and “C” are easily seen, and if you click on the sketch to enlarge it and look carefully, you’ll see another faint star at the southern edge of the primary. What the heck is that??? (East & west reversed to match the refractor view).

I found “B” was surprisingly easy to see for a star listed with a magnitude of 13.05.  So I checked the visual magnitude in Simbad, and found it listed there at 11.3, which may actually be brighter than what I saw. It’s hard to be sure, though, since “B” is nine arc seconds closer to the primary than “C”. At any rate, it’s magnitude is certainly brighter than 13.05.

And then there’s that “companionable” mystery star clinging to the primary at a position angle of about 165 to 170 degrees. How did it get there, how did John Herschel miss it, and how did S.W. Burnham miss it???

To start at the beginning, Chris Thuemen sent both Steve Smith and I a photo of HJ 697 a few months ago which hinted at the existence of an unlisted component at the primary’s south edge:

Click to enlarge.

Click to enlarge.

A short while later, Steve was able to get a photograph showing the mystery star very clearly:

I’ve flipped both photos to match the mirror-image refractor view shown in my sketch above.   Click on the image to enlarge it.

To avoid confusion, I’ve flipped both photos to match the mirror-image refractor view shown in my sketch above. Click on the image to enlarge it.

And of course, after seeing Steve’s photo, I wondered if it would be possible to visually detect the mystery star in a six inch refractor.  As my sketch above shows, it was, although it required some intense scrutiny and patience.  But there was no doubt it was visually accessible, which takes us back to my questions a few paragraphs back.

Sir John Herschel’s observation of HJ 697 is shown below (the source can be found here), which shows the “B” and “C” components, but makes no mention of the mystery star.   You might notice his separations for the two components are noticeably different than the current measurements, although his position angles are close (“nf 20” is equal to 70° and “sf 30” equals 120°). More than likely his numbers are estimates.

Notice that Herschel’s observation of HJ 698 is also included here.   Click on the image for a larger view.

Notice that Herschel’s observation of HJ 698 is also included here. Click on the image for a larger view.

Surprisingly, S.W. Burnham didn’t include any comments on the mystery star either, even though he observed and measured HJ 697 twice:

Click to enlarge the image.

Click to enlarge the image.

Equally mysterious is how that star could have been missed with the apertures Burnham was using.   You’ll notice two notations in the fifth column from the left, which are explained on page iv of the second volume of his 1906 General Catalogue of Double Stars Within 120° of the North Pole.   β3 refers to the 18 ½ inch Clark refractor at the Dearborn Observatory in Chicago and β5 refers to the 40 inch Clark refractor at Yerkes Observatory.   You’ll also notice he lists “B” with a magnitude of 13 in 1878, but revised it to 11.7 in 1901, which matches closely with what I observed.

As to how the mystery star got there or where it came from, the most likely explanation is it’s a background star that was hidden behind the primary when Burnham made his observations. If there was ever anyone who put an eye to an eyepiece who could have detected that star, it was S.W. Burnham.   The proper motion of the primary is almost nil (+001 +015), but perhaps the mystery star has enough proper motion to allow it come into view in the hundred plus years since Burnham made his observations.

But to stir the mystery a bit more, I came across this 1999 photograph, which also shows the mystery star quite clearly.   In fact, its position relative to all three of the HJ 697 components matches those of Steve’s photo rather closely, even though there’s an interval of fourteen years between the two photos.

 HJ 697 1999 POSS II Band N, click to enlarge.

HJ 697 1999 POSS II Band N, click to enlarge.

So I’m not sure what to think at this point, except that the sky is a strange place. You never know what you’ll find lurking around the next celestial corner.

Many thanks to Dave Arnold for his reply to my email inquiry, to Brian Mason of the USNO for supplying data and answers, to Chris Thuemen for catching sight of a speck of light in his photograph, and to Steve Smith for definitively resolving that speck of light into a star.  Chris also introduced me to the Σ 700-ARN 63-WEB 3-HJ 698 area with one of his photos, which whetted my appetite for further investigation of those stars.

Next time out, as a result of inspiration provided by another reader of these pages, we’ll wander down to Canis Major and follow in the telescopic footprints left by Sir James South.

Clear Skies and stable seeing!   :cool:

Click on the image for a larger view!

Click on the image for a larger view!

Drifting Down River in Eridanus, Part Two: HJ 2224 and HJ 3626, HJ 23 and Σ 527, and Σ 514

Part One of this binary series on Eridanus covered 40 Eridani (aka Omicron² Eri), and in this second segment we’re going to use that same star as a base for exploring the sky immediately around it. In fact, we’re going to stay within a two degree radius of 40 Eridani, which might lead you to believe we can’t get lost. At least that’s what I thought before I strode off confidently into the dark with my diagram in hand . . . . . . . but it wasn’t long before I was spinning around like a compass needle in search of a non-magnetic north. So my advice is to bring along a bag of bread crumbs – it won’t hurt to leave a trail behind you to find your way back to 40 Eridani.

First, a wide view to give us some context:

 If you’ve never floated down the river Eridanus, you’ll find it situated just west of Orion. In fact, its headwaters, located at Beta (β) Eridani (aka Cursa) begin three and half degrees north and slightly west of Rigel. Follow the river west to Mu (μ) and Nu (ν) Eridani, where it turns to the southwest, and then float downstream until you’re wedged between Omicron-1 (O1) on the north bank and Omicron-2 (O2)/Keid on the south bank. (Stellarium screen image with labels added, click on the chart for a larger view).

If you’ve never floated down the river Eridanus, you’ll find it situated just west of Orion. In fact, its headwaters, located at Beta (β) Eridani (aka Cursa) begin three and half degrees north and slightly west of Rigel. Follow the river west to Mu (μ) and Nu (ν) Eridani, where it turns to the southwest, and then float downstream until you’re wedged between Omicron-1 (O1) on the north bank and Omicron-2 (O2) on the south bank. (Stellarium screen image with labels added, click on the chart for a larger view).

 Point your telescope at the glowing gold of fourth magnitude Omicron-2 (O²) and then study this close-up view of the area surrounding it:

Along with their Bayer designations, O1 and O2, these two stars also go by Beid and Keid.  We’re going to look at three groups of two stars each: HJ 2224 and HJ 3626, Σ  527 and HJ 23, and Σ  514 and Beid.  (Stellarium screen image with labels added, click for a larger view).

Along with their Bayer designations, O1 and O2, these two stars also go by Beid and Keid. We’re going to look at three groups of two stars each: HJ 2224 and HJ 3626, Σ 527 and HJ 23, and Σ 514 and Beid. (Stellarium screen image with labels added, click for a larger view).

Stellarium screen image with labels added, click to enlarge.

Stellarium screen image with labels added, click to enlarge.

Let’s start with the first pair of the three groups, HJ 2224 and HJ 3626. Since I’ve been here and been lost, I can probably save you some time and some frustration. The easiest way – this is no guarantee, so don’t eat those bread crumbs – is to center O²/40 Eridani/Keid in your finder and then look one degree south in search of 7.80 magnitude HIP 19871. Center it, and then look another degree west and slightly south, and you should see seventh magnitude HJ 2224 with 5.70 magnitude HIP 19511 parked about 16’ due west of it. If you travel diagonally southwest from O² to HJ 2224, the distance is 1.5 degrees.

Once you’ve located HJ 2224, move it to the northwest corner of your eyepiece and the faint ninth and tenth magnitude paired light of HJ 3626 should come into view in the southeast corner.

HJ 2224   HIP: 19590   SAO: 131020               HJ 3626   HIP: 19707   SAO: 131040
RA: 04h 11.9m Dec: – 08° 50’                            RA: 04h 13.3m Dec: – 09° 28’
Magnitudes: 6.55, 9.76                                        Magnitudes: 9.10, 9.81
Separation: 56.7”                                                  Separation: 20.4”
Position Angle: 306° (WDS 2011)                      Position Angle: 38° (WDS 2010)
Distance: 536 Light Years                                   Distance: 2065 Light Years
Spectral Classification: G5                                 Spectral Classification: F5

HJ 2224 is seen parked up in the far northwest corner of the view, and HJ 3626 is diagonally opposite in the southeast corner. The rest of the field is faint and rather un-interesting, except for the out of reach A 471, with a separation of .4” (WDS 1991) between its 9.2 and 9.5 magnitude components. (Click on the sketch to enlarge it for a much better view).

HJ 2224 is seen parked up in the far northwest corner of the view, and HJ 3626 is diagonally opposite in the southeast corner. The rest of the field is faint and rather un-interesting, except for the out of reach A 471, with a separation of .4” (WDS 1991) between its 9.2 and 9.5 magnitude components. (Click on the sketch to enlarge it for a much better view).

As carefully as you have to look to see the secondary of HJ 2224 – there’s three magnitudes of difference between it and the primary, but fortunately, at 56.7” of separation, there’s plenty of space between them – you have to look even closer to grasp the weakly paired lights of HJ 3626. Both of those stars are basically as faint as HJ 2224’s secondary, but these two dim stars are also almost four times as far away.

Sir John Herschel discovered HJ 2224 sometime around 1830 and HJ 3626 was first recorded in 1835. His original published versions of his observations are shown below (this is a compilation from two different sources, here and here), and as you can see if you compare his data with the WDS data above, there’s been little change in HJ 3626.  On the other hand, the position angles and separation of HJ 2224 have changed noticeably: from a PA of 319.6° to 306°, and from from 30” to 56.7” in separation.

JHershel on HJ 2224 and HJ 3626

Click on the image for a better view.

Click to enlarge.

Stellarium screen image with labels added, click to enlarge.

Now let’s go back to O²/40 Eri/Keid and use it as a starting point for our next pair of stars. With your finder centered on Keid, you should see the 5.9 magnitude glow of HIP 20271 one and a half degrees due east. You’ll find Σ 527 located two-thirds of the way along, and slightly north, of the line between HIP 20271 and Keid. Once you have it, move Σ 527 to the south edge of your eyepiece and look slightly west of the north corner of the field of view for the dim flickering puffs of light that are HJ 23.

Σ 527  (H II 80)  HIP: 20137  SAO: 131108               HJ 23    No HIP or SAO
RA: 04h 19.0m Dec: – 07° 25’                                    RA: 04h 18.0m Dec: -07° 00
Magnitudes: 8.16, 10.38                                              Magnitudes: 10.0, 11.0
Separation: 6.6”                                                             Separation: 46.3”
Position Angle: 196° (WDS 2010)                              Position Angle: 275° (WDS 1999)
Distance: 553 Light Years                                           Distance: ?????
Spectral Classification: F0                                          Spectral Classification: ?????

Both of these pairs require some intense visual scrutiny at the low magnification used for the sketch, but I was restricted by very poor seeing. (East & west reversed to match the refractor view, click on the sketch to get a much better view).

Both of these pairs require some intense visual scrutiny at the low magnification used for the sketch, but I was restricted by very poor seeing. (East & west reversed to match the refractor view, click on the sketch to get a much better view).

The seeing was not only incredibly poor on the night I made the sketch, but there was a lot of murk in the air which made it more difficult to catch sight of the faint companion of Σ 527, as well as both components of HJ 23. The 18mm Radian I used for the main sketch was barely enough to split Σ 527, and the 14mm Radian I used for the inset in the lower right was almost hopeless.  I had to sit still and watch several minutes in order to glimpse a solid split.

Due to their faint tenth and eleventh magnitudes, the HJ 23 pair wasn’t any easier. In fact, HJ 23 is so obscure you’ll find its twin orbs of weak light aren’t even identified with Herschel’s catalog number by most star plotting software. Adding to the difficulty of tracking down this pair of dim stars is the presence of a few similarly spaced faint pairs north of the real HJ 23. So if you want to catch this dim Herschel duo, the best advice I can give is to stick with parking Σ 527 at the edge of a low magnification field of view, which should bring HJ 23 into view. As an added aid – every little bit of information helps in this case – the distance between Σ 527 and HJ 23 is 24’, and the position angle of a line drawn from Σ 527 to HJ 23 measures 354°.

Lewis' Data for STF 527 and Herschel on HJ 23

Click to enlarge.

You can see in the top half of the data shown at the left, which comes from Lewis’ compilation of Struve’s double stars, there has been very little change in Σ 527 over the past two centuries. Below that is Herschel’s observation of HJ 23, which is interesting because of his estimated separation of 30” to 40” for the two stars. His position angle of “2 np” translates to 272° in our modern usage, so it appears there has been little change in position angle.  Because of Herschel’s estimated distances, though, it’s rather hard to come to any conclusion about how much change has taken place in the separation. The WDS listing for HJ 23 includes a note that the pair is optical, so whatever change has taken place since 1830 is due to the proper and radial motions of the two stars.

Now we’ll go back to O²/40 Eri/Keid and move northwest one degree to the yellow-white glow of fourth magnitude O² Eridani, also known as Beid, also known 38 Eridani (here’s the second chart from above). Now Beid is NOT a double star, but it comes in handy as a reference point for finding our last target for this tour, Σ 514. You’ll find it shining – or trying to – just 12’ due east of Beid, and it’s almost as visually obscure as HJ 23 was.

Σ 514    No HIP Number    SAO: 131031
RA: 04h 12.7m Dec: – 06° 50’
Magnitudes: 8.94, 10.70
Separation:  8.1”
Position Angle: 75° (WDS 2010)
Distance: ?????
Spectral Classification: “A” is K2

Look carefully! Σ 514 is sitting due east a mere 12’ from Beid’s yellow-white glow, halfway to the edge of the field of view. (East & west reversed once more to match the refractor view, click on the sketch for much better view).

Look carefully! Σ 514 is sitting due east a mere 12’ from Beid’s yellow-white glow, halfway to the edge of the field of view. (East & west reversed once more to match the refractor view, click on the sketch for much better view).

This pair of stars is deserving of a higher magnification, but seeing was still horrible, restricting me to a 26mm Celestron Plössl — any more magnification only resulted in a hard to focus blur. I put Omicron¹/Beid at the center of the view mainly to add some visual spice to the scene, but also as reference point for Σ 514. 37 Eridiani, which managed to sneak into view in the west corner, was an obvious white. As added information of interest, O¹/38 Eri/Beid is a 4.03 magnitude F1 star and 37 Eri is a 5.44 magnitude G8 star.

Click to enlarge.

Click to enlarge.

Lewis’s data on Σ 514 is at the right, which includes Struve’s original observational data, and shows very little change in position angle and separation over the past two centuries. Faint though they may be, this is a very static pair of stars. The proper motion from both Simbad and the WDS backs that up, showing motion of .016” per year east and .023” per year south (+016 -023) for the primary.  No data is shown for the secondary, but it appears to be moving right along with the primary, indicating some kind of physical relation (not orbital) between the two stars.

And that pretty well exhausts the double star selection in the O¹/O² region of Eridanus, at least for those targets within reach of a four to six inch refractor. We’re going to move east for our next tour and pay another visit to Orion before it slides over the western horizon for the season.

Stay tuned, and clear skies! :cool:

Drifting Down River in Eridanus, Part One: 40 Eridani (Omicron-2 Eri)

Every now and then I stumble across a star that pulls me into a whirling vortex with all the force of a one million solar mass black hole.  I suspect I have Mr. Spock to blame for this one, since as it turns out the creators of Star Trek placed his home planet, Vulcan, in motion around 40 Eridani.   But that star has also been tagged with numerous other names, such as Keid, Omicron-2 Eridani, d Eridani, H II 80, and STF 518.   And to steal a phrase from Mr. Spock, there are things about this star that “just aren’t logical, Jim.”   Which is something of an under-statement.

So where do we begin . . . . . . .

I think we’ll do what Cap’n Kirk would do if he wanted to fly the Enterprise to Vulcan – determine where it is.  Of course we could just ask Spock, except that he’s already on Vulcan cooking dinner for us.

Eridanus (the name means river) is a long, dim, and circuitous constellation which winds its way through the sky beginning at the southwest edge of Orion.  I’ve only shown the north section of it here.  (Stellarium screen image with labels added, click for a larger view).

Eridanus (the name means river) is a long, dim, and circuitous constellation which winds its way through the sky beginning at the southwest edge of Orion. I’ve only shown the north section of it here. (Stellarium screen image with labels added, click to enlarge).

Now that we have a rough idea where we’re going, we can zoom in several light years:

40 Eridani is labeled here as O2 (Omicron-2), along with its seemingly close companion, O1.  In reality, those two stars are nowhere close to each other.   Omicron-2  is located a mere 16.4 light years from us, while Omicron-1, at 125 light years, is seven and half times more distant from planet Earth.  (Stellarium screen image with labels added, click to enlarge the chart).

40 Eridani is labeled here as O2 (Omicron-2), along with its seemingly close companion, O1. In reality, those two stars are nowhere near each other. Omicron-2 is located a mere 16.4 light years from us, while Omicron-1, at 125 light years, is seven and half times more distant from planet Earth. (Stellarium screen image with labels added, click on the chart to enlarge it).

Time to fasten your seat belt and pull it tight.  We’re about to warp our way through inter-stellar space as fast as this ship will go.  Since we only have a short trip of 16.4 light years, we should be there in time for dinner at Spock’s abode.  Hope you have a taste for Vulcan shellfish and Romulan ale.

Omicron-2  (Keid)  (40 Eri)  (H II 80)   (Σ 518)             
HIP: 19849   SAO: 131063
RA: 04h 15.3m   Dec:  -07° 39’
.             Magnitudes         Separation     Position Angle    WDS Dates
A, BC:   4.51,   9.70                82.40”                102°                    2011
AC:        4.51, 11.47                77.30”                 97°                     2011
AD:        4.51, 12.17             481.40”                 38°                     1998
AE:        4.51, 12.50             569.90”                  24°                     1998
BC:     10.02, 11.47                  8.20”                331°                     2011
BD:     10.02, 12.20             452.60”                  28°                     1998
BE:     10.02, 12.50              559.50”                 16°                     1998
Distance: 16.4 Light Years
Spectral Classifications:  “A” is K0, “B” is G9, “C” is M5

I first stumbled across 40 Eridani quite innocently at the end of December (2013) on a dark and murky night, which was appropriate since it seemed to be enshrouded in mystery at first glance.  The four inch refractor I was using was nowhere near enough aperture for the murky atmosphere, which only made the mysterious even more mysterious.  To shorten what became a long story, hardly anything in my sketch matched the three star charting software programs I consulted, nor did it match well with the photos I ferreted out of various internet sites.

It was obvious I needed to go back for a more detailed look.  But true to winter-time form, the weather refused to cooperate except on bright moonlit nights that overwhelmed my primary quarry, the twelfth magnitude “D” and “E” components.  In the meantime, Eridanus was creeping lower in the southwestern sky and nearer to a cluster of ravenous star-starved coastal pines.  And then, just as I was about to give up hope for this season, I found myself looking at a clear sky as the sun set on the last day of February.  As dark descended, I could see Sirius and Rigel sparkling like airport beacons on steroids, but I decided to defy  the poor seeing with my 9.25 inch SCT.  I needed an extra dose of aperture to pull the troublesome twelfth magnitude twins, “D” and “E”, out of the oceanic murk.

Finally, as darkness dropped its black curtain over the entire sky, I gritted my teeth and aimed the SCT at 40 Eridani.  Not expecting much from the shuddering seeing, I started with a 26mm Plössl (94x) in hopes it would be enough to unearth “D” and “E” from the murk.  It worked, but just barely:

I discovered “D” and “E” were easier to see if I placed the primary at the bottom of the field, which pulled the two fainter stars away from the edge of the eyepiece.  As I stared into the dusky gold glow coming from the primary, I couldn’t help but wonder if there really was a Spock out there.  Despite the less than lustrous 9.70 magnitudes of light radiating from “B”, I could see a persistent stream of blue photons flowing from it.   (East & west reversed to match the SCT view, click on the sketch to bring it to life).

I discovered “D” and “E” were easier to see if I placed the primary at the bottom of the field, which pulled the two fainter stars away from the edge of the eyepiece. As I stared into the dusky gold glow coming from the primary, I couldn’t help but wonder if there really was a Spock out there. Despite the less than lustrous 9.70 magnitudes of light radiating from “B”, I could see a persistent stream of blue photons flowing from it. (East & west reversed to match the SCT view, click on the sketch to bring it to life).

An unexpected bonus was the delicate split of the BC pair, which I was able to improve with a 12mm Radian (204x).  The actual view was quite a bit mushier than the sketch, though, and it took a determined effort to cobble the trembling pair into a series of mental snapshots resembling a stable image – sort of a mind over matter counterpart to photographic stacking of several images.

Now that we’ve covered the visual aspect of 40 Eridani, it’s time to slip into its whirling vortex of details.   Make sure that seat belt is still snug.

First, if you look at the WDS or Stelledoppie entry for 40 Eridani, you’ll see the first date of observation is 1783, but no mention is made as to who made that observation.  Fortunately, that date points directly to Sir William Herschel, who was apparently the only person on the planet obsessed with double stars that year.  And the reason for pointing out that point is that Herschel’s is a very interesting observation (source, sixth title down).

Herschel on 40 Eridani

This is actually Sir William’s observations of both BC and AB, but he treats BC as double (his catalog number is H II 80) and ignores the AB connection.  It’s somewhat confusing on first reading, but the first three lines refer to BC, and the last two to “A” and “B”.

Starting with the first line, in the statement “About 1 1/3 min s. following d Eridani”, his ”d refers to 40 Eridani (meaning the primary, “A”).   On the third line, Herschel gives the position angle for the BC pair – his “56° 42’ n. preceding” translates to 326° 42’ in our current system for measuring position angles.  On the fourth line, in the statement “Distance of L. from d Eridani”, the “L.” refers to “B”, the “Larger” star of the BC pair.  He then provides the distance of “B” from d Eridani, which he puts at 1′ 21″ 47”’ (81.78”), as well as the position angle – his “Position of L. 17° 53’ s. following d Eridani” translates to 107° 53’.

Before we go on, if you’re wondering where the “d” for 40 Eridani “A” came from, look no further than Flamsteed’s 1753 Atlas Coelestis:

40 Eridani, aka Omicron-2 Eridani, is shown dead center in this excerpt from Flamsteed’s 1753 atlas.  If you look closely, you’ll see a “d” attached to the right side of it up against the declination line.  Above and to the right of it at about a forty-five degree angle, parked tightly against another star, is Omicron-1 Eridani, which appears to be labeled with a ”b”.  (Click on the image for a larger view – image reproduced from the atlas available at the Atlas Coelestis link above).

40 Eridani, aka Omicron-2 Eridani, is shown dead center in this excerpt from Flamsteed’s 1753 atlas. If you look closely, you’ll see a “d” attached to the right side of it up against the declination line. Above and to the right of it at about a forty-five degree angle, parked tightly against another star, is Omicron-1 Eridani, which appears to be labeled with a ”b”. (Click on the image for a larger view – image reproduced from the atlas available at the Atlas Coelestis link above).

Burnham, p. 380

Burnham, p. 380

The second amazing thing we discover as we delve deeper into the whirling vortex is that F.G.W Struve observed 40 Eridani BC in 1825 and was unable to measure the distance separating the two stars because they were too close – a rarity for an early Struve observation.  But remember, Herschel described “C” as “hardly visible” at 227x and “very obscure” at 460x.  It wasn’t until 1851 that the BC pair was finally measured, with the meticulous Reverend Dawes only able to make an estimate of 3”, while Otto Struve, using a larger telescope, contributed a more exact 3.91” that year, followed by 4.14” in 1855.  But his position angles of 155.8° and 154°, respectively, sound a clangorous note with the 2011 WDS figure of 331°.  (All of that information comes from S.W. Burnham‘s 1906 catalog and can be seen by clicking on the thumbnail images at the right  or by going to this link for a slightly different version).

Burnham, p. 381

Burnham, p. 381

And it turns out there’s a very good reason for the dissonant clang.  “C” is in a 252 year orbit around “B” that varies from twenty-one astronomical units to forty-nine AU (an astronomical unit, or AU, is the distance between the earth and Sun).  Fortunately, as fate would have it, “B” and “C” are about as far apart as they can get at the moment – 2013 marked their furthest point of separation, so they’re beginning to slowly close now.  Their orbital data can be seen here.  (On p. 381 at the immediate right, “A and a” is AD, “A and b” is AE).

But as we descend further into the vortex, we also find “B” is in orbit around “A.”  That orbit is much larger, since it takes “B” about 7200 years to make a full circuit around “A”, and the separation between the two stars is much larger, at least 400 astronomical units according to James Kaler’s information on 40 Eridani.

So what we have here is a real rarity: a genuine, gravity bound triple star.  And the rarity is even more rare than that  – because all three stars are dwarf stars of varying flavors.

The primary is one of the very few class K (orange) dwarfs visible to the naked eye.  In fact, “A” is only four-tenths as luminous as the Sun, which means if it was a few dozen light years further away, it would fade from naked eye view.  “B” is a genuine white dwarf in the true sense of the meaning of dwarf.  It has passed through its final stage of stellar evolution, having shed its outer envelope of gases completely, and is now estimated to be about one and a half times the radius of the earth with an average density of about a quarter of a ton per cubic centimeter.  Despite its diminutive radii, it burns at an astronomical 16,700 degrees Kelvin.

Last, but hardly least, “C” is a red dwarf with a mass equivalent to sixteen hundredths of the Sun’s mass and glows at a cool temperature of 3500 Kelvin.  Despite that cool temperature, it shines almost as brightly as does “B”, which has a mass equivalent to half of the Sun’s.  But “C” has another characteristic that sets it apart from most stars in the sky – it’s a flare star, meaning its magnetic field shorts out at unpredictable intervals, causing it to suddenly become brighter (a short discussion is included in Kaler’s discussion of 40 Eridani).

That takes us to the last curled up corner of our whirling vortex, the one that caused me so much consternation when comparing my four inch refractor sketch with star plotting software and photos.  The Simbad chart below provides the first clue to why nothing matched my sketch:

Click on the chart for a larger view.

Click on the chart for a larger view.

This chart is a correct image view of proper motion – in other words, it matches what you would see visually without a telescope – whereas my sketch is a refractor (mirror-image) view, meaning it reverses east and west.  So the long red arrows (there are three if you look closely) on the chart are pointing to visual southwest.  Those arrows illustrate the proper motion of the “A”, “B”, and “C” components of 40 Eridani.

There’s one very important thing to point out about this chart.   In the upper left corner you’ll see the radius of view shown in arcminutes.   Normally, Simbad defaults to a 10 arcminute view, which is what most of the Simbad charts I’ve included in the past have been.   But in the case of 40 Eridani, a ten arcminute view was nowhere near large enough to capture all the motion shown on the chart.  I had to set the chart for a 50 arcminute radius (five times larger than normal) in order to capture all of the motion of the three stars.

Which gets us to the reason my four inch refractor sketch didn’t match the photos and star charting software I compared it with.  The three orbitally linked components of 40 Eridani (“A”, “B”, and “C”) are, relatively speaking, racing southwest across the sky.  In fact, the 40 Eridani system ranks twelfth in rate of proper motion among the stars in the Hipparcos Catalogue.  If you’re wondering what those other stars are, you’ll find a list of them here.

Looking at the specific numbers for all five of the stars associated with  40 Eridani in the WDS, we find Simbad lists these values for their proper motion:

      Simbad Data                    What the Data Means in Arcseconds per Year
“A”:  -2240  -3420                                      2.240” west, 3.420” south
“B”:  -2228  -3377                                      2.228” west, 3.377” south
“C”:  -2239  -3419                                      2.239” west, 3.419” south
“D”:  +0039 -0042                                      0.039” east,  0.042” south
“E”:  +0009  -0001                                     0.009” east,  0.001” south

When you combine the southern and western components of motion for “A”, “B”, and “C”, you get these values for total arcseconds of motion per year:  for “A”, 4.083”;  and for “B” and “C”, 4.073” each  (those values come from this source:  “A” is here, “B” is here, and “C” is here).  Also, the proper motions of both “D” and “E” clearly point to both of them having no physical relation whatever to the A-B-C trio.

That brings us to the final segment of this 40 Eridani Odyssey.

When I was lost in space, mired in a mystified muddle because the background stars in my first sketch didn’t match well with other sources, attempting to locate “D” and “E” gave me no end of tortuous trouble.  Once I discovered how quickly 40 Eridani “A”, “B”, and “C” were moving relative to other background stars, it was obvious that a history of the measures of AD and AE would provide a window into the past.   Brian Mason at the U.S. Naval Observatory, home of the Washington Double Star Catalog (WDS), was kind enough to provide me with that data, from which I put together three charts.

First, though, I needed some current measurements of AD and AE (the WDS data measures are from 1998), so I turned to Steve Smith, who had also clued me in on the 40 Eridani connection with Vulcan.  After taking a photograph of the 40 Eridani system, Steve employed his expertise with AutoCad to provide this work of art:

Using the 2011 data for AB as a reference point, Steve came up with the AD and AE measurements listed in the top left corner of the chart.   (This is also a mirror image view, meaning it matches the refractor or SCT view.  Click for a larger version, and thanks to Steve for use of the chart).

Using the 2011 data for AB as a reference point, Steve came up with the AD and AE measurements listed in the top left corner of the chart. (This is also a mirror image view, meaning it matches the refractor or SCT view. Click for a larger version, and stellar thanks to Steve for use of the chart).

Now we’ll add the historical observational data provided by Brian Mason to plot the configurations of AD and AE from 1850 to 2014.  Because both “D” and “E” are twelfth magnitude stars, meaning they aren’t visible except through a telescope, we’ll return to the same mirror-image refractor/SCT view used in my sketch at the beginning of this post.   So once again (unlike the correct image Simbad views), west will be on the left side of the view and east on the right:

AD is shown in the left half of the sketch and AE is on the right side.   Click anywhere on the image for a larger view.

AD is shown in the left half of the sketch and AE is on the right side. You’ll have to enlarge the chart by clicking on the image in order to see the detail.

If you were looking at 40 Eridani “A” in 1850, you would have seen 12.17 magnitude “D” south and very slightly west of “A”.   Otto Struve’s measurement of the position angle for that year was 197.0° and the separation was 128.3”.  Just thirty-six years later, you would find “D” was almost due east of “A” – Asaph Hall’s 1886 measures put the position angle at 94.05° and the separation at 40.46”.  And so on until 2014, when we see “D” parked northeast of “A” at about 37° and a distant 541”.

Looking at 12.50 magnitude “E” in relation to “A” in 1850, you would find it sitting almost due west.  Otto Struve’s measurements for that year were 278.7° and 99.4”.  A mere fourteen years later, you would have to look northwest of “A” to find “E” – August Winnecke’s 1864 measures were 312.5° and 89.4”.  And by 2014, we find “E” situated at 25° and 627” from “A”.

Now the amazing thing is, if you combine the left and right halves of the sketch, you’ll realize that in 1850 the alignments of AD and AE are nothing at all like what we see in 2014.

Notice the magnitudes are not scaled to match the actual view on these charts.   Click on the chart for a larger version.

Notice the magnitudes are not scaled to match the actual view on these charts. Again, click on the image to see the detail.

BUT – keep in mind, it’s not “D” and “E” that are responsible for the changes in positions you see .  It’s the trio of “A”, “B”, and “C” that are moving in relation to “D” and “E”.   (To keep things simple, only “A” is shown on the charts).

So what would it look like if we reversed the eyepiece plots above in order to show what is actually occurring?  Let’s put “D” and “E” at the center of our eyepiece view and cut “A” loose to move freely:

Now we have DA on the left of the sketch and EA on the right.  Click to enlarge!

Now we have DA on the left of the sketch and EA on the right. Click to enlarge and see the detail!

So there you have a very comprehensive view of a very interesting triple star system, one which would do perfectly fine on its own without the additional dimension of interest added to it by considering 40 Eridani as the location of Mister Spock’s home planet, Vulcan.

Which reminds me, we’re almost there, and dinner will be served shortly.   Pull up whatever passes for a seating device and prepare yourself for a voluptuous Vulcan dinner.   By the way, I recommend eating for several minutes before sipping the Romulan ale – it can play havoc with the head when the stomach is empty!

Desert is coming up shortly – a tour of a group of John Herschel and F.G.W Struve pairs within shuttle-hopping distance of 40 Eridani.

Clear Skies!  :cool:

P.S: And thanks to Steve Smith, Brian Mason, and Chris Thuemen for their contributions to this overly long dissertation.

Leapin’ Into Lepus: Beta(β) and Gamma (γ) Leporis, HJ 3759, HJ 3780/Bu 321, and S 476

Riding in the sky just below Orion is a dim, but distinctive, little constellation which goes by the name of Lepus, meaning the Hare, as in rabbit – to which it bears not an Iota (ι) of resemblance.  Somehow Johann Bayer was able to super-impose the image of a rabbit on the constellation’s stars, for which you have to give him credit for a vivid imagination.  James Kaler describes it as resembling an old box kite, but to me it looks like the two rectangular wings of some strange pre-historic bird.  But, considering Lepus is under-foot of Orion because it’s his prey, a pre-historic bird just isn’t going to work.   On the other hand, Orion’s gaze actually seems to be fixed on Taurus, not Lepus, which explains why the Hare hasn’t been harried by the Hunter for the past millennia.

But there’ll be no more splitting of hares here.  Instead, let’s pay a visit to little Lepus and try to ignore the looming figure of the Hunter as he strides through the sky above us, absorbed in a bovine obsession with the Bull.

As I mentioned, dim though it is, you really can’t miss the distinctive outline of Lepus stretching beneath Orion’s feet:

Stellarium screen image with labels added, click to enlarge.

Stellarium screen image with labels added, click to enlarge.

And here, labeled in turquoise are the five starts we’re going to look at:

We’ll stay close to the box-like wings that form the main body of this constellation in order to avoid getting lost in the host of dim stars surrounding it.  (Stellarium screen image with labels added, click for a larger view).

We’ll stay close to the box-like wings that form the main body of this constellation in order to avoid getting lost in the host of dim stars surrounding it. (Stellarium screen image with labels added, click for a larger view).

Let’s get started with a multiple star with multiple names that’s really less complicated than the data might lead you to believe.   If you center Alpha (α)Leporis in your finder, you’ll find the multiple starlight of HJ 3780/Bu 321 a short 1.5 degrees due east of it.

HJ 3780/Bu 321              HIP: 26602   SAO: 150652
RA: 05h 39.3m    Dec:  -17° 51’
Identifier            Magnitudes        Separation    Position Angle     WDS
Bu 321    AB:      6.69,  7.83                 0.50”                160°              2008
HJ 3780  AC:     6.69,   8.89              89.30”                137°              2012
HJ 3780  AE:     6.69,   7.90              75.60”                    9°               2012
HJ 3780  AF:      6.69,   8.25           133.90”                300°              2012
HJ 3780  AG:     6.69, 11.24              59.60”                  51°              2012
HJ 3780  AH:     6.69, 12.70              40.80”                308°             1999
HJ 3780  AB, I:  6.69, 10.94              91.80”                103°              2000
HJ 3780  CD:    8.89,   9.55                1.40”                 352°              2006
HJ 3780  CI:      8.89, 10.94              52.40”                  33°              1999
Distance: 1305 Light Years
Spectral Classification: “A” is B7

A first glance at HJ 3780 will bring you eye to eye with four distinct and obvious stars, and a closer inspection in a five or six inch refractor will net you two more:

All the stars here are white, but what really strikes me about this view is a calmness that seems to radiate from it.  I’m not sure where that comes from, but the almost perfect symmetry of the arrangement of the four brightest stars might have something to do with it.  If you look closely, you’ll see an elongation in “C”, which was surprising due to murky and shaky seeing.   I looked and looked for “H”, but it was buried too deeply in the glare of the AB primarial pair to be seen.      (East & west reversed to match the refractor view, click on the sketch for a better view).

All the stars here are white, but what really strikes me about this view is a calmness that seems to radiate from it. I’m not sure where that comes from, but the almost perfect symmetry of the arrangement of the four brightest stars might have something to do with it.  (East & west reversed to match the refractor view, click on the sketch for a better view).

What you’re actually looking at is a small open cluster of about six arc minutes in diameter, NGC 2017.  Here’s another version of the sketch, with the outer boundaries of the cluster shown and each of the stars labeled:

 If you look closely, you’ll see an elongation in “C”, which was surprising due to murky and shaky seeing. I looked and looked for “H”, but it was buried too deeply in the glare of the AB primarial pair to be seen.  (East & west reversed, click to improve the view).

If you look closely, you’ll see an elongation in the CD pair, which was surprising due to murky and shaky seeing. I looked and looked for “H”, but it was buried too deeply in the glare of the AB primarial pair to be seen. (East & west reversed, click to improve the view).

STScI Photo

STScI Photo, click to enlarge the view.

Whether this striking collection of stars is really an open cluster is an – ahem – open question, but chances are it isn’t.  Even a deeper look at this area fails to reveal a wealth of background stars, as the STScI photo at the left shows.   But what it does show is the star that eluded me, 12.70 magnitude “H”.

John Herschel swept his 18.5 inch reflector across this area of the sky on December 11th, 1835, when he was at the tip of southern Africa’s Cape of Good Hope, mysteriously describing it as “Quintuple, 6th and 7th classes, magnitudes 7, 7, 8, 8, 8” —- mysterious because there are only four stars of similar magnitudes visible, not five.

Burnham on Bu 321In 1877 S.W. Burnham detected three stars missed by Sir John with his large instrument (Burnham’s observation can be seen by clicking on the thumbnail image at the right), which were 7.83 magnitude “B” (then at a distance of 1.06”), 9.55 magnitude “D” (then at a distance of 1.56”), and 12.70 magnitude “H” (at a distance of 41.79” in 1878).  All those were detected with his formidable six inch f/15 Clark refractor, which is probably indicative of the difference between an early 1830 speculum-coated mirror and the optical quality achieved by Clark and Sons in the latter half of the nineteenth century – not to mention Burnham’s acute visual skill.  Why CD and AH aren’t identified as Bu 321 is a puzzle I’ll leave to another time.

As for now, let’s wander down to Beta (β) Leporis, which you’ll find three degrees south and slightly west of Alpha (α) Leporis.   You should be able to pick it out of the sky visually since the primary is a third magnitude star (here’s our second chart again).

Beta (β) Leporis  (Nihal)  (9 Leporis) (HJ 3761)  (Bu 320)
HIP: 25606   SAO: 170457
RA: 05h 28.2m   Dec:  -20° 46
Identifier           Magnitudes      Separation      Position Angle       WDS
Bu 320     AB:   2.90,   7.50               2.60”                     3°                  2008
HJ 3761   AC:  2.90, 12.00             58.50”                140°                  2000
HJ 3761   AD:  2.90, 11.99           210.40”                  73°                  2000
HJ 3761   AE:  2.90, 10.50           242.80”                  59°                  2000
Distance: 159 Light Years
Spectral Classification:  “A” is G5

As you can see from the identifiers in the left column above, it looks like the same two stellar characters we just encountered, Burnham (Bu) and the junior Herschel (HJ), were loitering around here as well.

Splitting the AB pair, Bu 320, was out of the question because of erratically nervous seeing, but I was able to pry the twelfth magnitude “C” and “D” companions out of the sky as the primary shimmered in a yellow-white haze.   Down in the southwest corner of the eyepiece, SEE 53, an 8.70 and 8.98 magnitude pair separated by 0.20” at 99° (WDS 2014), refused to reveal any hint of duplicity.  (East & west reversed, click on the sketch to enjoy the yellow-white haze).

Splitting the AB pair, Bu 320, was out of the question because of erratically nervous seeing, but I was able to pry the twelfth magnitude “C” and “D” companions out of the sky as the primary shimmered in a yellow-white haze. Down in the southwest corner of the eyepiece, SEE 53, an 8.70 and 8.98 magnitude pair separated by 0.20” at 99° (WDS 2014), not surprisingly refused to reveal any hint of duplicity. (East & west reversed, click on the sketch to enjoy the yellow-white haze).

Burnham’s data on Beta (β) Leporis, click for a larger view.

Burnham’s data on Beta (β) Leporis, click for a larger view.

You may have noticed the name attached to this star, Nihal, which comes from the Arabic phrase “al-nihal”, meaning “the camels beginning to quench their thirst.”  Instead of explaining that, I’ll refer you to James Kaler’s write-up on the star, which is full of additional tantalizing information such as a temperature almost identical to the Sun.  He also mentions the “B” companion has been classified as dim as eleventh magnitude, raising the possibility as to whether “B” has an unseen eclipsing companion.  Whatever the case, it must have been somewhere near the current WDS magnitude of 7.50 when Burnham discovered it with his six inch refractor in 1875.

SEE 53, the star at the southwest corner of the eyepiece previously mentioned in the caption under the sketch above, has a prefix I’ve never come across in my stellar ramblings.  It belongs to Thomas Jefferson Jackson See, a controversial character described as erratic, pompous, and rancorous.  A short biography can be found here and a longer version is available here.

On to Gamma (γ) Leporis now, a third magnitude star glowing four degrees southeast of Beta (β), where it holds down the southeast corner of the constellation’s eastern wing.  Here’s our second chart once more.

Gamma (γ) Leporis  (13 Leporis)  (AB is H VI 40; BC is H V 50)
HIP: 27072   SAO: 170759
RA: 05h 44.5m   Dec:  -22° 27’
Magnitudes   AB: 3.64, 6.28     BC: 6.28, 11.37
Separations  AB: 95”                 BC: 112.10”
Position Angles   AB: 350° (WDS 2012)    BC: 8° (WDS 1999)
Distance: 29 Light Years
Spectral Classifications:   “A” is F6, “B” is K2
Notes:  High proper motion   “A”: -292 -369   “B”: -304 -352   “C”: +006 +012

This triple star quickly captured all of my attention on the very first glance:

Along with the deep yellow color of the primary, the distinctive line-up of the “B” and “C” companions with the primary results in a comparatively rare configuration of stars.  I added the labeled inset at the right to eliminate any confusion with the cluster of stars around the primary, none of which have apparently been linked with “A”. (East & west reversed to match the refractor view, click on the sketch to bring it to life).

Along with the deep yellow color of the primary, the distinctive line-up of the “B” and “C” companions with the primary results in a comparatively rare configuration of stars. I added the labeled inset at the right to eliminate any confusion with the cluster of stars around the primary, none of which have apparently been linked with “A”. (East & west reversed to match the refractor view, click on the sketch to bring it to life).

Among the list of names assigned to Gamma  Leporis (γ) in the data above are two William Herschel catalog numbers with an almost poetic ring, H VI 40 and H V 50.  An unusual aspect of Herschel’s numbering of these stars (link for the source below) is his decision to distinguish between AB and BC in his measures, which probably has something to do with the fact that he measured them seven months apart.

Wm. Herschel on Gamma Leporis

What stands out about his distance measures are how far they differ from the WDS figures.  His 2.5 minutes (150”) for AB contrasts with the WDS figure of 95” for 2012.  The 40’ (forty arc minutes) he shows for BC is an error – it should read 40” (forty arc seconds), which contrasts with the 1999 WDS measure of 112.10”.

It’s really a shame Herschel didn’t include position angles because both Gamma Leporis “A” and “B” have very significant rates of proper motion, which comes as no surprise since they’re relatively close to us at a distance of 29 light years.  I included the proper motion data for all three components in the last line of the data above.  What those numbers mean is “A” is moving west in right ascension at the rate of .292” per year and south in declination at the rate of .369” per year; “B” is moving .304” west and .352” south per year; and in contrast, “C” is almost still, moving at the rate of .006” east and .012” north per year (+006 +012).

Here’s a Simbad plot which illustrates the proper motion of “A”:

Click on the image for a larger view.

Click on the image for a larger view.

For some reason “B” is excluded from that plot, but it’s motion would be almost identical.

What would the three stars of Gamma (γ) Leporis look like if you project their positions backward in time?  Here’s a 1977 photo which shows the change in relative positions of the three stars in just thirty-five years for AB and twenty-two years for BC:

Click on the image for a larger view.

Click on the image for a larger view.

For comparison’s sake, the WDS figures for AB are 350° and 95” and for BC 8° and 112.10”.  So what we’re seeing as we project forward from 1977 is “A” and “B” are moving closer together and “B” and C” are moving farther apart, while the position angles in each case are shifting around to the north.  And those trends also coincide with William Herschel’s separations as well.

Now before all that motion through the sky sets your head spinning, let’s move on to a more stable pair, HJ 3759, and a new chart.

Stellarium screen image with labels added, click to enlarge the chart.

Stellarium screen image with labels added, click to enlarge the chart.

First, let’s move back to Beta (β) Leporis and center it in our finder.  If you look closely, you’ll find HJ 3759 located a degree north and slightly west of Beta (β).  At sixth magnitude it stands out clearly from the few background stars visible in a finder.

HJ 3759      HIP: 25397   SAO: 150442
RA: 05h 26.0m   Dec:  -19° 42’
Magnitudes:  5.87, 7.30
Separation:   26.7”
Position Angle: 318°  (WDS 2011)
Distance: 140 Light Years
Spectral Classification: “A” is F5, “B” is F7
Notes: Proper motions are   A:  +003 -019  B: +010 -024

This pair is a refreshing change from what we’ve seen up to this point thanks to both the colors and the lack of distracting background stars.  The primary is gold and the secondary has a very definite but subtle tinge of blue.  (East & west reversed again, click on the sketch to enrich the colors).

This pair is a refreshing change from what we’ve seen up to this point thanks to both the colors and the lack of distracting background stars. The primary is gold and the secondary has a very definite but subtle tinge of blue. (East & west reversed again, click on the sketch to enrich the colors).

Even though I saw gold and blue in the two stars, their spectral classifications would argue I should have seen two white stars, and in fact that’s what this Aladin photo shows.  As I’ve mentioned before, star colors can be unpredictable, so your view may vary.  ;)

Click to enlarge.

Click to enlarge.

I included the proper motion figures in the data above for the HJ 3759 pair just to compare them with our previous star, Gamma (γ) Leporis.  The numbers clearly indicate much less movement, which is in line with the differences in distance of the two stars, 29 light years for Gamma (γ) and 140 for HJ 3759, and is obvious when comparing the WDS data above to the 1877 and 1893 data in Burnham’s 1906 catalog shown at right.

Here’s the Simbad plot which provides a visual portrayal of the proper motion numbers above for HJ 3759:

Click on the image for a larger version.

Click on the image for a larger version.

Now we’ll continue working our way northwesterly to our last star, S 476 (here’s that last chart once again).  From our current position at HJ 3759, you’ll see seventh magnitude HIP 25324 a short 21’ to the northwest.  When you extend the line that runs through it and HJ 3759 another two degrees, a slight arc of three stars pointing northwest will come into view.   The first of the three is sixth magnitude S 476 — the other two are 5.95 magnitude HIP 24786 and 6.75 magnitude HIP 24649.

S 476         HIP: 24825   SAO: 150335
RA: 05h 19.3m   Dec:  -18° 31’
Identifier         Magnitudes       Separation      Position Angle         WDS
S 476       AB:  6.31,  6.48              38.20”                   20°                   2012
STU 20    AC:  6.31, 9.57            166.90”                   21°                    2011
Distance: 792 Light Years
Spectral Classifications:  “A” is B5, “B” is B8

Like Gamma Leporis (γ), this is another triple star with the components all pointing in one direction, but in this case, the three stars of S 476 come within a degree of forming a straight line.

At almost identical magnitudes, the primary and secondary are instantly recognizable, while 9.57 magnitude “C” floats off in the distance about four times further than the short interval separating “A” and “B”.  Both stars were white with a slight tinge of yellow, which I suspect was caused by their low position in the sky at the time I caught them.

At almost identical magnitudes, the primary and secondary are instantly recognizable, while 9.57 magnitude “C” floats off in the distance about four times further than the short interval separating “A” and “B”. Both stars were white with a slight tinge of yellow, which I suspect was caused by their low position in the sky at the time I caught them.

James South measured the AB pair of this triple star system twice in 1824, coming up with an average of 39.713” for the separation and 17° 19’ for the position angle (source).

Click on the image for a larger view.

Click on the image for a larger view.

There isn’t much proper motion to these two stars, but in looking at the data in the WDS it appears the secondary is creeping southward from the primary (“A”: +002 +009, “B”: +005 -007), which would explain the almost three degrees of difference between South’s position angle and the WDS figure.

The “C” component was first measured in 1988 by K.M. Sturdy and was published by the Webb Society in one of their double star circulars (Number 5, 1988 to 1992), from which I took the excerpt included below:

Click to enlarge the image.

Click to enlarge the image.

There is a large discrepancy between the initial 1988 separation of AC (128.07”) and the 2011 WDS figure, 166.90”.  There are seven observations recorded in the WDS for STU 20, so presumably the 2011 separation figure is the more accurate of the two.

And that takes care of Lepus for this year.   There’s plenty more in this small and dim constellation worth tracking down, so with any luck I’ll get back here again next year.   Next time out, we’ll look at a narrow swath of sky in the meandering constellation of Eridanus, so stay tuned . . . . . . .

. . . . . . . and Clear Skies!   :cool:

A Tale of Two Tough Characters: Rigel and Tau (τ) Orionis

I’ve lost track of the number of times I’ve looked at Rigel, aka Beta (β) Orionis, but one thing that hasn’t escaped from my memory is the first time I viewed it in a 60mm refractor.  What stands out most clearly about that night was the moment I first caught sight of a flickering spark of light at the blinding primary’s southwest edge, something I really hadn’t expected to see.  That faint flickering spark was the 6.80 magnitude secondary, which is also double, although with a separation of only 0.10” I certainly didn’t notice.

I was reminded of that first 60mm refractor view of Rigel just a few weeks ago when I wandered just north of it to another difficult star, Tau (τ) Orionis.   Both stars are similar in their wide magnitude spreads, 6.50 magnitudes between Rigel and its BC secondary, and 7.30 and 7.40 magnitudes between Tau (τ)’s primary and the two stars that accompany it.  They both also boast of doubled up secondaries, but with the difference that the average backyard double star diehard has a fighting chance to wrestle Tau’s BC pair apart.

So in some ways this is a sojourn down one of the more difficult paths to double star nirvana, but it’s more a steady uphill climb than a hand-over-hand hoist to the top of a steep precipice.  After all, Rigel is very splittable with a 60mm refractor, although I can’t say the same for Tau (τ).  Nevertheless, difficult though they are, neither of these stars are really all that far out of reach, and both share one very important and redeeming attribute: they’ll sharpen your observing skills, provided you’re patient and are willing to persevere under a cold winter sky.

First, for those unfamiliar with the area, a chart displaying our destination:

You'll find Rigel and Tau (τ) holding down the southwest corner of Orion.  (Stellarium screen image with labels added).

You’ll find Rigel and Tau (τ) holding down the southwest corner of Orion. (Stellarium screen image with labels added).

We’ll wrestle with Rigel first and then we’ll give Tau (τ) a try.

Rigel  (Beta [β] Orionis)  (19 Orionis) (Σ  668)  (H II 33)
HIP: 24436   SAO: 131907
RA: 05h 14.5m    Dec: – 08° 12’
Identifier             Magnitudes       Separation      Position Angle     WDS
STF 668  A,BC:  0.30,   6.80               9.30”                  204°              2011
Bu 555       AD:   0.30, 15.40            44.60”                     1°                2008
Bu 555       BC:   7.50,   7.60              0.10”                    30°               2005
Distance: 773 Light Years
Spectral Classifications:  “A” is B8, “B” is B9

The challenge with Rigel lies in learning to see past its zero magnitude glare in order to visually excavate the seventh magnitude secondary buried there.  Every time I look at Rigel, I have to give my eyes time to adjust to that glare.

This sketch doesn’t quite convey the glare surrounding Rigel, nor does it do justice to the sudden visual and emotional impact of first sighting the secondary. But it’s close enough to give you a reasonable idea of what to expect. Nothing matches the real thing, though. So if you haven’t turned a telescope toward Rigel, time’s a wastin’! (East & west are reversed to match the refractor image, click on the sketch for a much better view).

This sketch doesn’t quite convey the glare surrounding Rigel, nor does it do justice to the sudden visual and emotional impact of first sighting the secondary. But it’s close enough to give you a reasonable idea of what to expect. Nothing matches the real thing, though, so grab a coat and a telescope and take a look. (East & west are reversed to match the refractor image, click on the sketch for a much better view).

Your first view is the hardest, not only because of the glaring battle you’re face to face with, but also because it’s hard to visualize what the secondary will look like in that glare.  More than likely your first sighting of it will sneak up on you unexpectedly, meaning you’ll suddenly discover you’ve been staring at it for several seconds without realizing it.  The first time I saw it I remember an eerie sensation – I had an uncanny feeling it had been looking back at me for quite a while before I recognized it for it was.  Weak as the secondary is in comparison to the primary (about four hundred times fainter), once your eyes have adjusted for the glare and that secondarial speck of light has registered in your brain, you’ll find it’s very sharp and very distinct.  There isn’t any guessing about whether you’re actually seeing something or whether your imagination is playing tricks, which has been my experience with Sirius.

Rigel  is frequently described as something of a training tool for visually sighting the secondary spinning around Sirius, which is accurate to a point — that point being the difference in the distinctiveness of the secondaries.  I’ve caught sight of the Sirius secondary (aka the “Pup”) several times this year, but each time I’ve been less than overwhelmed by the experience.  While sighting the Pup is a greater challenge, it’s a faint ghostly presence that plays tricks with your mind, whereas there isn’t any guessing about whether you’ve spotted Rigel’s secondary.  And there’s a good reason for the difference.  As of early 2014, Sirius “A” and “B” are separated by 10.1”, very similar to the separation of Rigel “A” and “BC”, but Sirius “B” is 9925 times fainter than Sirius “A”.

Now after you’ve wrestled Rigel into submission and are basking in the radiant blue-white primarial glory of your secondarial success, stop for a second and think about that secondary’s secondary  –  the “C” part of Rigel BC, the star that’s only 0.10” distant from “B”.  Think about the challenge of detecting an elongation in that BC pairing.

Impossible, right?  Not quite.

Not only was it done with a six inch refractor, but it was done twice.  In fact, the first hint that Rigel “B” was duplicitous was actually provided by a six inch f/15 Clark achromatic refractor.  And, not surprisingly, at the eyepiece of that instrument – both times – was none other than Sherburne Wesley Burnham.  He did get a slight break – apparently the separation of the BC pair was close to 0.20”, as opposed to 0.10”.

Click to enlarge.

Click to enlarge.

The full account of S.W.’s adventure is shown at the right, and it’s well worth reading.  As it turns out, the first solid confirmation came from the 36 inch Clark refractor at Lick Observatory (also an achromat), and even then it took several attempts, first because of poor seeing conditions, and second because the separation between the two stars apparently had narrowed to below 0.10”.  Note the magnifications required with that instrument, though – 2000x to 3000x!

So before you strenuously pat yourself on the back after your first success with Rigel “B”, pause to consider the level of visual skill wielded by Burnham.  Not that any of us will ever quite get there – and the pat on your back is well deserved, by the way – BUT, remember, there’s always another level of achievement to be had beyond your most recent one.

Like Tau (τ) Orionis.

Tau (τ) Orionis  (20 Ori)         HIP: 24674   SAO: 131952
RA: 05h 17.6m   Dec: -06° 51’
Identifier              Magnitudes       Separation      Position Angle     WDS
H V 25        AB:    3.60, 11.00             33.30”                   251°             2011
HJ 2259    AD:    3.60, 10.90             35.40”                     60°              2011
Bu 188      BC:  11.00, 10.90               3.80”                     51°              2011
Distance: 555 Light Years
Spectral Classifications: “A”is B5, “D” is G6

Located a mere one and a half degrees north and slightly east of Rigel, Tau (τ) Orionis is an experience of a different sort.  There’s less glare since the primary is over three magnitudes fainter than Rigel “A”, but there’s a wider magnitude separation between the primary and its two companions, “B” and “D”, which makes them about a thousand times fainter than the primary – and one of the stars is actually fainter than that.  The fact that they’re both almost four times further from the primary than the distance separating Rigel’s A-BC pair doesn’t seem to count for much in the advantage column.

On first glance, you’ll more than likely find a single star staring back at you.  But with persistent use of averted vision – and five or six inches of aperture – you’ll find this image gradually emerging:

 “D” will emerge first from the glare surrounding the primary, and with persistence and at least average seeing conditions, “B” will gradually make itself known on the primary’s opposite side.  The primary, by the way, is brightly white.  (East and west reversed, click on the sketch to bring “B” and “D” to life).

“D” will emerge first from the glare surrounding the northeast side of the primary, and with persistence and at least average seeing conditions, “B” will gradually make itself known on the primary’s opposite side. The primary, by the way, is brightly white. (East and west reversed, click on the sketch to bring “B” and “D” to life).

Even though Tau (τ)’s primary isn’t as bright as Rigel, it still throws off enough glare to make things difficult.  And despite the WDS data which shows only a tenth of a magnitude of difference between the two eleventh magnitude companions, “D” is noticeably easier to see than “B”.  I had to scoop up every photon I could find with my averted vision in order to keep “B” in view, and even then it had a nasty tendency to fade from sight.  Simbad shows “B” with a visual magnitude of 11.8 (compared to 11.0 for the WDS) and “D” at a visual magnitude of 10.9, which is more in line with what I saw.

And right there is the crux of a problem.

The WDS data shows the significantly harder to detect “B” companion as a William Herschel discovery, H V 25 – and it’s a little difficult to believe he would have cataloged that companion and ignored “D”, which is so much easier to see.  In fact, as it turns out, Herschel didn’t provide a position angle for the star he included in his 1780 description (twelfth title down):

Wm. Herschel on H V 25

.
.
In his 1906 Catalog, Burnham states the senior Herschel failed to see “D”, but that it was added by the junior Herschel, John, in his Fifth Catalogue . . . . . . .

Burnham on Tau Orionis

.
. . . . . . . so I dug out the entry in John Herschel’s Fifth Catalogue and found this . . . . . .

John Herschel on Tau.
. . . . . . . which isn’t a lot of help.   Even though that entry shows position angles and separations, none of them are reasonably close to either Burnham’s data or the current WDS data.  However it does show that John Herschel noticed the difference in magnitudes of the “B” and “D” companions, which again leads me to conclude the star William Herschel recorded in his observation is the brighter “D” on the east side of the primary, not the fainter “B”.

Enough of that.  There’s still a visual challenge we haven’t wrestled with yet, and that’s the BC pair.

Given how difficult it was for me to keep “B” in view, I wasn’t sure it was even worth the effort to attempt to pry it apart.  The seeing was poor – about a notch below average (a II on this chart) – and the glare from the primary was being magnified by a surplus of moisture in the air.  But with nothing to lose, I armed my six inch refractor with a 6mm AT Plössl  (253x) and finally detected a hint of an elongation – a very weak hint.  At that magnification, the primary was primarily a blob of unfocused light, and the image wasn’t helped in the least by a strong east wind that was making the visual observing life difficult.

So the challenge is still there to get a definite split from the BC pair, and it should be within reach of both a five and a six inch refractor given an atmosphere that’s willing to cooperate.  As temptation for what’s possible, here’s a photograph of the Tau (τ) system taken by Steve Smith which provides a good view of a distinctly separated BC pair.  It also shows quite clearly the disparity in magnitudes between “B” and “D”.

Photo used with the permission of Steve Smith, click to enlarge.

Photo used with the permission of Steve Smith, click to improve the view.

Credit for the inspiration to visit Tau (τ) goes to both Chris Thuemen, who sent me a photo of it hinting at an elongation in the BC pair — which in turn launched me on a long search for a good photograph of Tau BC — and to Steve Smith who went out and took the photo I was looking for.

As soon as the weather improves, the moon disappears, and the seeing cooperates, I’ll be back to tussle with Tau (τ) again.  If I can’t match the visual acuity of eagle-eyed S.W. Burnham, the least I can do is subdue Tau (τ) in order to get a taste of the satisfaction he must have felt when the elongation he saw in Rigel BC was confirmed.

Next stop – somewhere in the vicinity of Tau (τ).  Until then, clear skies!  :cool:

_______________________________________________________

Update: Giving into the “temptation for what’s possible.”

In the winter you’ve got to take the clear nights when they’re there, and when I finally found an unexpected one looming on the last day of February, Tau (τ) Orionis was still on my mind.  The seeing didn’t look any too great.  Sirius was doing what it’s done every clear night this winter, which is a polished imitation of an airport beacon flashing in red, green, and white — and Rigel was hard at work imitating it.  But I had already brought my 9.25 inch SCT out before dusk so it could cool down, and knowing Tau’s BC pair was going to demand plenty of aperture, I decided to see what would happen.   In the back of my mind, I was hoping a low magnification view would be enough to drive a wedge between “B” and “C”.

The seeing was pretty much what I expected — erratic, nervous, and even a bit blurred.   But with a 26mm Celestron Plössl at 94x, I could detect an elongated smudge of light radiating from the BC side of Tau (τ).  What really surprised me, though, was how difficult BC and D were to see in the primary’s glare, even with 9.25 inches of aperture.  But despite their battle with the glare, they were persistent enough to stay in view without resorting to averted vision.

Since I was having mixed success at 94x, I tried a 20mm AT Plössl (123x), which resulted in the same blurred elongation, but at least it wasn’t any worse.  Then I reached for an 18mm Radian, but somehow I managed to pick up the 14mm (175x).  “B” and “C” were now clearly separated — certainly not quite what you would call pleasingly precise points of white light — but once I realized I was seeing them at 175x, I decided to make one more determined seeing-defying leap to a 10mm Radian.  Using 245x on a night like this would normally be a sign of sitting in one place under a cold dark sky for too many hours, but since the night was still young, I convinced myself that since I didn’t expect anything more than unfocused blobs of bouncing light, I was still on the safe side of insanity.

Anyway, if you don’t try, you don’t know . . . . . . .

. . . . . . . and darned if those two blobs of light weren’t impossible to unscramble.

Esthetically pleasing they sure weren’t, but they were clearly separate:

This is what I saw, minus the blog effect, so don't be misled into thinking the view was quite this comfortable.   What it does do, though, is convey how much BC and "D" are subdued by the white primary's intense glare.   (East & west reversed to match the SCT view, click on the sketch to relive the experience).

This is what I saw, minus the blob effect, so don’t let the sketch mislead you into thinking the view was quite as comfortable as it appears. What it does do, though, is convey how much BC and D are subdued by the white primary’s intense glare. (East & west reversed to match the SCT view, click on the sketch to re-live the experience).

I had just a hint of what the inimitable eagle-eyed S.W. Burnham must have felt when he saw the elongation in Rigel’s BC pairing.  Subtle though it was, I stared at that dance of white light until my eyes began to cross.

And savored every single bouncing photonic moment of it.

Roaming through the Ram, Part Two: 10, 14, 30, and 33 Arietis

. . . . . . . . and A Short Study in Proper Motion

Time now to return once again to the land of the Ram, otherwise known as Aries, and continue our explorations in an eastward direction.   If you missed part one, you can find it here.

Before we get started, it’s been pointed out that I may have been too hard in part one on Aquila, Pegasus, and Pisces with regard to a lack of double star attractions.  Peter Morris has mentioned three stars in Aquila worth taking a look at (5, 15, and 57 Aquilae), one in Pegasus (Enif, aka Epsilon {ε} Pegasi), and four in Pisces (35, 65, Psi-1 {ψ-1}, and Zeta {ζ} Piscium).  I’ve looked at 57 Aql (here) and would agree with Peter – apparently it got lost in my double star cluttered cranium.   Enif I’m familiar with as marking Pegasus’ nose, but I was totally unaware of its double star status.  In fact, it’s actually a very interesting variable which is classed as a “flare” star.  Jim Kaler has some interesting information on it here.  As for Pisces, I’ll have to do some exploring – I need to spend more time in that constellation anyway.

At any rate, many thanks to Peter for his comments, which just point out how incredibly involved and numerous double (and multiple) stars are.  No matter how many years you spend on them, there are always more out there waiting for your eyes to take them in.   After all, there are over 125,000 double and multiple stars cataloged in the WDS (Washington Double Star Catalog), and when you allow for those too faint or too close for the average telescope, there are still plenty left to keep a person busy for years.  If only 25% of that total is within reach of the average backyard telescope (only a guess), that still leaves over 31,000 pairs to track down . . . . . . . and the (ahem) Ram-ifications of that are mind boggling.

On to Aries now.  This is the wide view of where we’re going:

You have to look carefully to locate Aries since it’s in an inconspicuous region of the sky, but once you become familiar with it, it stands out well.   Fortunately it’s not far from the Pleiades (about 25 degrees), which helps to pin it down.  (Stellarium screen image with labels added, click to enlarge).

Stellarium screen image with labels added, click to enlarge.

And this is a close up of the area with all eight of the stars on the two Aries tour labeled in blue:

We’re going to take a look at eight double or multiple stars over the course of two tours, all of which are labeled in blue in the chart above.  Quite a few of the eight are great targets for 60mm refractors, which I’ll mention along the way.  (Stellarium screen image with labels added, click for a larger view).

Stellarium screen image with labels added, click for a larger view.

We’ll pick up with 14 Arietis, which is conveniently located two and half degrees north of second magnitude Alpha (α) Arietis, aka Hamal.  You’ll find it conveniently parked about 25 arc minutes east of sixth magnitude 16 Arietis.

14 Arietis  (H VI 69)  (S 406)  (STTA 23)            HIP: 10053   SAO: 75171
RA: 02h 09.4m   Dec: +25° 56’
Magnitudes   AB: 4.99, 8.01    AC: 4.99, 7.97
Separations  AB: 93.30”          AC: 104.50”
Position Angles  AB: 34°  (WDS 2011)   AC: 279° (WDS 2012)
Distance: 320 Light Years
Spectral Classifications:  “A” is F2, “B” is K0, “C” is F2

And I admit to being swept off my feet immediately on first sight:

A nice wide pair, not the least challenging, that offers striking color and an eye-pleasing configuration.   (East & west reversed to match the refractor view, click on the sketch to improve the view).

A nice wide pair, not the least challenging, that offers striking color and an eye-pleasing configuration. (East & west reversed to match the refractor view, click on the sketch to improve the view).

My first view of this endearing triple star was in my six inch f/10 refractor, which yielded a yellow-white primary leaning toward gold.   I was back the following night with my 80mm f/15 Mizar refractor and struck true gold that time using a 26mm Celestron Plössl (46x).  I didn’t get a 60mm view of this system, but it should do quite well in a 60mm refractor.

Sir William Herschel was here on a winter evening in 1781 (December 27th) and surprisingly tied only one of the two nearby stars (now designated “C”) to the primary.

Wm. Herschel on 14 Ari

His position angle translates to 278° 48’ in our usage, which matches the 2012 measurement for “C”, but his separation of 89.5” is closer to the current WDS data for “B”, leaving me wondering if he didn’t measure it instead of the other star.  So I began to follow a trail of bread crumbs which led first to Sir James South.

James South on 14 AriSir South paid a visit to 14 Arietis twice in December of 1823 and, as you can see by clicking on the thumbnail image at the left, he also measured the star now identified as “C” while ignoring what is now identified as “B”  —–  BUT  —–  he did remark on the questionable separation provided by William Herschel.  Instead of casting a curious eye toward “B”, he attributed the questionable measurement to a problem with the micrometer device Herschel employed.

Not surprisingly, it took the discerning eye of S.W. Burnham to recognize what actually had happened, which he summed up quickly in his 1906 account of 14 Arietis, although where he referred to “angle”, I believe he meant separation since the angle is correct.

Burnham on 14 Ari

He also mentions the proper motion of both the primary and secondary, which we’ll return to shortly.

For now, though, let’s move on and over to 10 Arietis, which lies slightly more than a degree east of our current location (here’s the second chart again).

10 Arietis  (Σ 208)               HIP: 9621   SAO: 75114
RA: 02h 03.7m   Dec: +25° 56’
Magnitudes    AB: 5.82, 7.87   AB,C: 5.67, 13.50
Separations   AB: 1.48”            AB,C: 95.30”
Position Angles  AB: 346° (WDS 2014)    AB,C: 150° (WDS 2001)
Distance: 173 Light Years
Spectral Classification: “A” is F8, “B” is F9
Notes: AB is gravitationally linked — the orbit can be seen here.

This is the first double or multiple star on our two part tour of Aries that didn’t catch Sir William Herschel’s attention, and one quick look explains why:

This one is not for the faint of heart, and it’s certainly not material for a 60mm refractor!  The primary is an obscuringly bold white, while the secondary is barely visible in this view through a six inch refractor at 152x.  The 304x view in the inset at the right just about doubles the apparent distance between the two stars, but they still appear to be locked in a tight embrace.   (East & west reversed, click on the sketch to get a closer look).

This one is not for the faint of heart, and it’s certainly not material for a 60mm refractor! The primary is an obscuringly bold white, while the secondary is barely visible in this view through a six inch refractor at 152x. The 304x view in the inset at the right just about doubles the apparent distance between the two stars, but they still appear to be locked in a tight embrace. (East & west reversed, click on the sketch to get a closer look).

With two magnitudes of difference between the primary and a less than spacious separation of 1.47”, 10 Arietis requires aperture, good seeing, and a healthy dose of patience.  If you look closely, you’ll see 13.5 magnitude “C” lurking dimly at the southeast edge of the primary’s glow, which is no simple star to uncover either, given the ten magnitudes of difference between it and the 5.82 magnitude primary.  Clinging to the eastern corner of the view is 7.14 magnitude SAO 75122 at a distance of 9.5 arc minutes from 10 Arietis.

Lewis on 10 ArietisThe distance between the primary and secondary is slowly increasing at about .015 arc seconds per year.  With a long list of observations of the pair having been made over the past one-hundred ninety plus years (223 from 1821 to 2012), the orbital period of 325 years is pretty well pinned down (it has a grade of three in the WDS, with one being the most definitive and nine being the least definitive).  A list of the early observational data for the AB pair of 10 Arietis, along with an early attempt at plotting an orbit, can be seen by clicking on the thumbnail image at the right.

And once again, mention is made of proper motion in that excerpt from Lewis’s book, and again, we’ll get to that shortly.

Now we’ll take a long leap in an eastward direction in search of a much wider pair, 30 Arietis.   Here’s our second chart again, which you’re going to need.  Starting from our current location at 10 Arietis, hop back to 14 Arietis and continue east to sixth magnitude 16 Arietis and 5.8 magnitude 20 Arietis.  Then slide south about three quarters of a degree to 5.6 magnitude 21 Arietis.  From there we’ll traverse five degrees due east with a slight southern touch to reach our goal.  As you begin nudging your scope eastward, you should see the 6.5 magnitude glow of 30 Arietis come into view.

30 Arietis  (H V 49)  (SHJ 32)  (STTA 29)          HIP: 12189   SAO: 75471
RA: 02h 37.0m   Dec: +23° 49’
Identifier          Magnitudes        Separation    Position Angle      WDS
STFA 5         AB: 6.50,  7.02            38.00”                 275°               2012
RAO 8   Ba,Bb: 7.02, 11.00              0.50”                 286°               2013
Distance: 129 Light Years
Spectral Classifications: “A” is F5, “B” is F7

We’re back in more expansive territory now, which means this is another pair of stars that does well in a 60mm refractor.

Less demanding of our star splitting talent, the hushed yellow glow of this pair of stars is a comfort to our ocular apparatus.  The primary, being a half magnitude brighter than the secondary, is slightly richer in color.  (East & west reversed once more, click on the sketch for a more colorful view).

Less demanding of our star splitting talent, the hushed yellow glow of this pair of stars is a comfort to our ocular apparatus. The primary, being a half magnitude brighter than the secondary, is slightly richer in color. (East & west reversed once more, click on the sketch for a more colorful view).

This is a system that has more names than it does components, and appears to have been a stopping point for all of the double star greats.

Wm. Herschel on 30 Arieta

William Herschel was here on October 15th, 1781; James South and John Herschel on December 6th and 8th of 1821; and F.G.W. Struve and his son, Otto, came along shortly afterwards.

S. W. Burnham made his way to it in 1904 and came to the conclusion the primary and secondary were fixed in relation to each other, which would make them either an optical pair or a physical pair linked by proper motion.

Burnham on 30 Ari

The Washington Double Star Catalog (WDS), on the other hand, refers to an estimated orbital period of 34,000 years.  What we know for certain, as Burnham indicates, is the two stars are moving eastward at an almost identical rate.  Again, we’ll return to that subject shortly.

The most recent addition to 30 Arietis, RAO 8, came in 2012 as part of a project using a “visible-light laser-adaptive-optics instrument” on a sixty inch scope located on Mt. Palomar.  More on that project can be found here, including a photo at the top of page five of a pair of stars separated by 0.14”.

And finally, on to the final star in out Arietal tour, which is located 2.5 degrees northeast of our current location.  As you move your scope in that direction, you’ll see 33 Arietis lying just short of a degree south and west of 5.3 magnitude 35 Arietis.  (Here’s our previous chart once more).

33 Arietis  (H IV 5)  (SHJ 33)  (Σ 289)       HIP:12489   SAO: 75510
RA: 02h 40.7m   Dec: 27° 04’
Magnitudes: 5.30, 9.56
Separation:  29”
Position Angle: 3°  (WDS 2012)
Distance: 234 Light Years
Spectral Classification: A3, A2

I tracked this one down with my 80mm f/15 Mizar refractor, not really expecting to catch the secondary since it’s 4.26 magnitudes fainter than the primary.  Surprisingly I succeeded in prying loose the 9.56 magnitudes of faint light, although it was mainly an averted vision affair:

Needless to say, this one is not 60mm refractor material.  It’s also a rather lonely field, with not much of anything to draw your attention aside from 8.25 magnitude SAO 75522 in the southeast corner of the field.  But in an odd way, there’s something compelling about the sheer sparse quality of the view with the 5.3 magnitudes of white light at the center.  (East & west reversed once more, click on the sketch for a much better view).

Needless to say, this one is not 60mm refractor material. It’s also a rather lonely field, with not much of anything to draw your attention aside from 8.25 magnitude SAO 75522 in the southeast corner of the field. But in an odd way, there’s something compelling about the sheer sparse quality of the view with the 5.3 magnitudes of white light at the center. (East & west reversed once more, click on the sketch for a much better view).

Sir William Herschel was here on September 27th, 1779, and came up with measurements that are close to those of the 2012 figures shown above from the WDS.  His 87° 14’ should include the phrase “north following,” which would equate to 2° 46’ in today’s double star language.

Wm. Herschel on 33 Arietis

As for his statement about 33 Ari being “the first in the head of the fly” – a phrase I can’t say I’ve ever heard uttered in connection with a double star – it happens to be a reference to a now defunct constellation that at one time hovered over the back of the Arietal Ram.  It went by the name of Musca Borealis, which translates as The Northern Fly, and consisted of 33, 35, 39, and 41 Arietis.  You can find a discussion by Ian Ridpath here, and there’s a detailed 1822 plate showing the fly hovering over the Ram’s rear quarters here.

Click to enlarge.

Click to enlarge.

Speaking of 1822, James South and John Herschel recorded a visit to 33 Arietis on January 28th and February 1st of that year.  Their measurements differ very little from William Herschel’s, but what caught my eye were these comments: “Double; considerably unequal; large white, small blue.  The small star does not bear a good illumination.”  Keeping in mind they were using a 96.5 mm f/15 refractor, they couldn’t have been more correct about the faint secondary, and I’m amazed they were able to measure its separation – obviously it wasn’t easy, as the remark about it not bearing “a good illumination” indicates.

Now, on to a different aspect of all four of these stars which caught my attention as I looked up the details on them.

** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** ** **

A Short Study in Proper Motion

First, to set the stage so we’re all moving together in the same direction, proper motion at its most basic is the apparent motion of a star across the celestial grid marked out by right ascension and declination, and is measured in arc seconds per year.   But it’s also affected by the star’s distance and intrinsic speed, as well as the degree to which the star is moving directly toward us or away from us.  A more detailed — but very basic, informative, and condensed — discussion of proper motion can be found here in this outline of an Ohio State University lecture.  Another useful link is this 1999 discussion by Phil Plait of Bad Astronomer fame (he’s actually a pretty darn good astronomer).

Now – what captured my attention as I excavated information from my stellar vault about the four stars in this tour was the similarities in their rates and directions of motion.

First, I’ll list the proper motions that are known for each star in the tour:

14 Ari —  “A”: +071  -041   “B”: +065  -034    “C”: +074  -037
10 Ari —  “A”: +134 +010   “B”: +134 +010  (identical because gravitationally linked)
30 Ari —  “A”: +135  -015   “B”: +143  -014
33 Ari —  “A”: +065  -026   “B”: +065  -029

So – what do those numbers mean?  The first three of each six digit series is movement in right ascension (east or west), and the second group of three numbers is movement in declination (north and south).  A plus sign indicates eastward movement in RA and northward movement in declination, while a minus sign means westward motion in RA and southward motion in declination.

As for the numbers themselves, think of each three digit series of numbers as having a decimal in front of it.   In other words, in the case of 14 Ari, when your imagination supplies the decimal, this is what you would see: +.071 and  -.041  —-  and to complete the picture, we’ll add the symbol for arc seconds, which results in this appearance: +.071” and -.041”.

What those two numbers mean is the primary (“A”) of 14 Ari is moving eastward at a rate of .071” per year and southward at the rate of .041” per year.  The next set of numbers tells us the secondary (“B) is moving eastward at a rate of .065″ and southward at the rate of .034″ per year, and “C” is moving .074″ north and .037″ south per year.

As you can see by the plus signs in the RA columns, all of these stars are moving east, with 10 and 30 Arietis moving in that direction twice as fast as 14 and 33 Arietis.  Their rates of movement in declination are similar, with the exception that both components of 10 Arietis are moving slightly north, while the others are all moving toward the south.

Now, let’s put those figures above into pictorial form.  To save space and avoid clutter, I’ll combine the individual Simbad charts into two groups:

Simbad 14 and 10 Aries

Click on either of the charts to enlarge.

Click on either of the charts to enlarge.

Now, let’s take our proper motion table above and add the distance to each star:

14 Ari —  “A”: +071  -041   “B”: +065  -034    “C”: +074  -037    320 Light Years
10 Ari —  “A”: +134 +010   “B”: +134 +010                                    173 Light Years
30 Ari —  “A”: +135  -015   “B”: +143  -014                                    129 Light Years
33 Ari —  “A”: +065  -026   “B”: +065  -029                                    234 Light Years

Not surprisingly, the two fastest moving systems of the group, 10 Arietis and 30 Arietis, are the closest of the bunch.   Relative to 10 and 30 Arietis, the most distant of the group, 14 Arietis, is actually moving along at a rather respectable rate.   If it was half as far, it’s proper motion figures would be very similar to 10 and 30 Arietis.

What those figures don’t tell us is how fast the stars are moving towards us or away from us (their radial direction).  When you have that information, as the previously mentioned Ohio State University lecture shows in graphic form (there’s an excellent diagram labeled “True Space Motions” about three-fourths of the way down showing all of this), you have a complete picture of the actual motion of the star.

A couple of other items that show up on the charts above:

The large galaxy in the center of the plot for 10 Arietis is MCG+04-05-047, with a magnitude of 14.7 (in blue light).  More interesting still is the reference to a planet on the chart for 30 Arietis, which looks like this when we zoom in to a 5 arc minute view (the earlier four charts are all 10 arc minute views):

Click on the chart for a more planet friendly view.

Click on the chart for a more planet friendly view.

The object shown on that chart is thought to be either a very large planet or a brown dwarf with an orbital period of 335.1 days around 30 Arietis B.  Here’s a chart with all of the pertinent data, and here’s a short seven page paper which discusses both the planet and the host star.

For those interested, here are the links to the Simbad charts shown above:

14 Arietis
10 Arietis
30 Arietis
33 Arietis
30 Arietis with planet

Before I forget about it, here ‘s the link to the William Herschel, John Herschel, and James South excerpts from the Royal Society’s Philosophical Transactions.  Find the volume number mentioned at the bottom of the excerpt, click on it, and you’ll see a table of contents for all the articles in that volume.  Clicking on a title will provide you with a .pdf version of the article — lots of interesting titles in those old issues!  And this link will get you to volume two of Burnham’s 1906 double star catalog (volume one is here).

And that should be enough to keep you busy for a while on those cloudy nights when the stars refuse to show themselves. :cool:

Next stop will take us south to stellar realms I’ve never explored before, so stay tuned!

Roaming through the Ram, Part One: Gamma (γ) Arietis, Σ 221, 1 Arietis, and Lambda (λ) Arietis

Some constellations seem to have all the luck when it comes to distinctive double stars, and surprisingly the amount of celestial real estate they occupy has little to do with it.  Take Aquila, for instance, which spreads it wings over a wide swath of southern sky, but really has only one double star standout, Pi (π).   Or Pegasus, the flying horse, whose wings also need a lot of celestial space in which to work.  It’s home for several impressive clusters of galaxies (here and here and here), and you can’t miss its conspicuously squared asterism, but you would be hard pressed to find any autograph-worthy double stars decorating its heavenly terrain.   And then there’s Pisces, a long and winding right-angled constellation that only has one semi-famous double star to its credit, Alrescha.

Possibly one of the reasons Pegasus and Pisces are so deficient in distinctive double stars is because Aries stole across the Piscean border one evening and made a quick dark-of-night raid, grabbing a large handful from both constellations.  It may come as a real surprise (at least it did to me), but Aries is actually richly endowed with marvelous points of multiple starlight.

Now when telescopic attention is turned towards the Arietal Ram, most people with double star memories think of Gamma (γ) Arietis — also known as Mesarthim, also known as the Ram’s Eyes.  It’s a beauty, no question, with its two gloss-white 4.5 magnitude globes hovering just 7.5” apart in black sky.   But Gamma (γ) Arietis actually has a lot of competition.  And you don’t have to wander far at all from its dazzling twin white lights before you begin to encounter it.

You have to look carefully to locate Aries since it’s in an inconspicuous region of the sky, but once you become familiar with it, it stands out well.   Fortunately it’s not far from the Pleiades (about 25 degrees), which helps to pin it down.  (Stellarium screen image with labels added, click to enlarge).

You have to look carefully to locate Aries since it’s in an inconspicuous region of the sky, but once you become familiar with it, it stands out well. Fortunately it’s not far from the Pleiades (about 25 degrees), which helps to pin it down. (Stellarium screen image with labels added, click to enlarge).

We’re going to take a look at eight double or multiple stars over the course of two tours, all of which are labeled in blue in the chart above.  Quite a few of the eight are great targets for 60mm refractors, which I’ll mention along the way.  (Stellarium screen image with labels added, click for a larger view).

We’re going to take a look at eight double or multiple stars over the course of two tours, all of which are labeled in blue in the chart above. Quite a few of the eight are great targets for 60mm refractors, which I’ll mention along the way. (Stellarium screen image with labels added, click for a larger view).

And since it’s already been mentioned several times, let’s start with the most well-known of the group, Gamma (γ).

Gamma (γ) Arietis  (Mesarthim)  (Σ 180)  (H III 9)  (5 Arietis)
HIP: 8832   SAO: 92681
RA: 01h 53.5m   Dec: +19° 18’
Identifier        Magnitudes        Separation      Position Angle      WDS
STF 180   AB: 4.52,   4.58               7.50”                     2°                 2012
STF 180   AC: 4.52,   8.63          216.80”                   81°                 2012
STF 180   BC: 4.58,   8.63          215.70”                   83°                 2012
Bu   512   CD: 8.63, 13.60              1.60”                   24°                 1975
Distance: 204 Light Years
Spectral Classifications:  “A” is A1, “B” is B9

This one is unquestionably a delightful 60mm target, and in fact the sketch below is a 60mm refractor view:

 Two lovely white dots of luminescent light glowing silently in black space!  Few sights in the night sky equal this one in the head-snapping-to-attention category.  It’s a great object to get the double star juices flowing at the beginning of any observing session.  “C” is included in this sketch to the east (below and to the right) of the AB pair.  Bu 512, the CD pair, was just a wee bit beyond the grasp of the 60mm lens.  In fact, it’s also well beyond the grasp of my largest scope, a 9.25 inch SCT.  (East and west reversed to match the refractor view, click on the sketch for a much better version of it).

Two lovely white dots of luminescent light glowing silently in black space! Few sights in the night sky equal this one in the head-snapping-to-attention category. It’s a great object to get the double star juices flowing at the beginning of any observing session. “C” is included in this sketch to the east (below and to the right) of the AB pair. Bu 512, the CD pair, was just a wee bit beyond the grasp of the 60mm lens. In fact, it’s also well beyond the grasp of my largest scope, a 9.25 inch SCT. (East and west reversed to match the refractor view, click on the sketch for a much better version of it).

Greg covered Gamma (γ) Arietis well in a previous post,  so I won’t spend a lot of time on it.  But I have to point out he coined the best description of this pair of stars I’ve yet come across, “headlights on the mountain roads of autumn.”

Click on the image to enlarger it.

Click on the image to enlarger it.

Sir William Herschel gets credit for being the first person to provide statistical data on Gamma (γ), which took place on September 27th, 1779, but apparently he wasn’t the first person to corner it in a telescope.  R.G. Aitken credits Robert Hooke with coming across it in 1664, and according to the WDS notes file, Hooke commented, “I took notice that it consisted of two small stars very near together; a like instance to which I have not else met in all the heavens.”  As appropriate as that comment is to describing Gamma (γ) Arietis, I should add that I’ve searched Volume one of The Philosophical Transactions in which that statement is supposed to have appeared, and have had no luck whatever in turning it up.  It may be buried in there somewhere, but it’s certain it doesn’t appear on page 150, as referenced in the WDS note file.  If a reader happens to locate that quote, I’ll be glad to provide a link to it.

Meanwhile, we’ll wander over to Σ 221, which can be a real pain to pin down, so I’ll add another chart for it here:

Stellarium screen image with labels added, click on the chart for a larger version.

Stellarium screen image with labels added, click on the chart for a larger version.

The path to Σ 221 isn’t all that difficult, provided you have the correct location – which I didn’t on the first attempt.  There are actually several ways to get there.   The easiest, if you’re using an 8×50 finder with the customary five degree field of view, is to center the finder midway between 2.65 magnitude Beta (β) Arietis and 5.23 magnitude Eta (η) Arietis, which are four degrees apart.  In the central part of the field you’ll see 5.85 magnitude HIP 9307 and 7.55 magnitude HIP 9815 pointing right at our goal, 8.05 magnitude Σ 221.  You can also pick it out of the sky slightly south of the halfway point between 5.23 magnitude Eta (η) and 5.72 magnitude 15 Arietis — it lies about twenty-five arcminutes west of the line extending between those two stars.

Σ 221  (H III 68)         HIP: 10088   SAO: 75175
RA: 02h 09.7m   Dec: +20° 21’
Magnitudes   AB: 8.13, 9.45     AC: 8.13, 12.40
Separations  AB: 8.40”             AC: 66.70”
Position Angles:  AB: 146° (WDS 2007)   AC: 227° (WDS 2000)
Distance: 1450 Light Years
Spectral Classifications: “A” and “B” are both A3

This is the dimmest of the entire group of eight stars on this tour, but it makes up for its lack of light with its subtle colors:

You need five or six inches of aperture to get the full benefit of the colors – a very delicate gold-yellow-white for the primary and a weak blue for the secondary – but they’re quite obvious when seen against a black background.  The “C” companion can be seen just left of the pale gold primary.  (East & west reversed, click on the sketch to enjoy the coloration).

You need five or six inches of aperture to get the full benefit of the colors – a very delicate gold-yellow-white for the primary and a weak blue for the secondary – but they’re quite obvious when seen against a black background. The “C” companion can be seen just left of the pale gold primary. (East & west reversed, click on the sketch to enjoy the contrasting coloration).

Click to enlarge.

Click to enlarge.

This pair was also visited by Sir William Herschel (on September 10th, 1782), who provided very accurate directions which still work quite well over 230 years later.  His 55° 42’ south following translates in our current usage to a position angle of 145° 42’, which is very close to the 2007 WDS measure of 146°.

Burnham identifies the “C” component, which was first measured in 1856, as Wn 1 (Winnecke) on p. 22 of volume one of his 1906 catalog, an identifier no longer assigned in the WDS and one that doesn’t match the current Winnecke Double Star Catalog.  The AC pair seem to be widening slowly, with Winnecke measuring the separation at 61.0” in 1856, Burnham measuring it at 63.40” in 1904, and the last measure in the WDS being at 66.70.”  (Burnham 1906 Catalog, Volume 1, p. 22, and Volume 2, p. 323).

Now let’s go back to Beta (β) on our second chart (click here to open it in a second window) and we’ll head north to 1 Arietis, aka Σ 174.  You’ll find its 2.90 magnitude glow slightly less than two degrees northwest of Beta (β), where it forms a triangle with Beta (β) and 5.92 magnitude 7 Arietis.

1 Arietis  (Σ 174)  (H I 73)        HIP: 8544   SAO: 74966
RA: 01h 50.1m   Dec: +22° 17’
Magnitudes: 6.33, 7.21
Separation:  2.8”
Position Angle: 165° (WDS 2012)
Distance: 574 Light Years
Spectral Classification:  “A” is G3

This close pair eluded me completely on my first attempt due to poor seeing, but I had enough of a glimpse of its potential to work up an appetite for a return visit.   Although it took several nights before the sky cooperated, it was well worth the wait:

This is an absolutely stunning pair at the center of a very sparse field.  The primary is a dot of gold-white light and the secondary is slightly smaller and almost the same color.   Both globes of light are made all the more intense  because of the surrounding void.  East & west are reversed once more, click on the sketch to improve the view considerably.

This is an absolutely stunning pair at the center of a very sparse field. The primary is a dot of gold-white light and the secondary is slightly smaller and almost the same color. Both globes of light are made all the more intense because of the surrounding void. East & west are reversed once more, click on the sketch to improve the view considerably.

I was so intrigued by this pair that I returned several nights later with my 80mm f/15 Mizar refractor and coaxed them into an absolutely beautiful split with a 15mm TV Plössl, which surprised me until I later discovered Greg had pried it apart in a 60mm Tasco at 96x and 128x.  That’s not something I would have thought to try because of the one magnitude of difference and close separation, so give Greg credit for pushing the limits on this pair . . . . . and he says he doesn’t have Burnham-like double star vision!

And again, Sir William paid this pair a visit (November 22nd, 1782), which he described as “a considerable star.”

Wm. Herschel on 1 Arietis

Now on to the last stop on this tour, Lambda (λ) Arietis.  It’s 4.80 magnitudes of compound light is easily found just a bit over two degrees northeast of 1 Ari, or two degrees west of second magnitude Alpha (α).  (Here’s the chart once more).

Lambda (λ) Arietis  (H V 12)  (SHJ 23)  (STTA 21)  (9 Arietis)
HIP: 9153   SAO: 75051
RA: 01h 57.9m   Dec: +23° 36’
Magnitudes   AB: 4.80,6.65   AC: 4.80, 9.70   AD:4.80, 9.88
Separations  AB: 37.10”        AC: 188.70”       AD: 270.10”
Position Angles  AB: 48° (WDS 2012)   AC: 76° (WDS 2005)   AD: 85° (WDS 2012)
Distance: 133 Light Years
Spectral Classifications: “A” is F0, “B” is F7, “C” is K

Hmmmmmmm – haven’t we seen these colors somewhere before?  East & west reversed to match the refractor view, click on the sketch to bring the background stars to life.

Hmmmmmmm – haven’t we seen these colors somewhere before? East & west reversed to match the refractor view, click on the sketch to bring the background stars to life.

This pair is a virtual carbon copy, at least color-wise, of the second pair of this tour, Σ 221 . . . . . . . or maybe it’s the other way around – hard to know which pair emerged from its cocoon of hydrogen gas and galaxial dust first.  At any rate, the primary’s soft yellow and the secondary’s hint of blue provide just the right touch of class for the intriguing patterns of scattered starlight surrounding it.  The “C” and “D” components balance the view by hanging out distinctively on the east side of the primary/secondary pair.  And you can certainly add this foursome to the list of stars that does well in a 60mm refractor.

And who else but Sir William again . . . . . . .

Wm. Herschel on Lambda Arietis

I don’t know what to say about the colors he recorded, especially the garnet for the secondary, but his separation and position angle measurements match well with the 2012 WDS numbers (his 42° north following is 48° in the current usage).

Sirs James South and John Herschel did better in the color department, as the excerpt below from their 1824 catalog shows (scroll down to the bottom of the page at that link).

Click on the image for to enlarge it.

Click on the image for to enlarge it.

The WDS has dropped the Herschel/South identifier from Lambda, but I came across it in the second volume of Burnham’s 1906 catalog (page 317), where he identifies it with the contemporary prefix, Sh 23.  Herschel and South credit Struve with a measure of Lambda (λ), but it isn’t listed in Struve’s 1827 Catalogus Novus Stellarum Duplicium et Multiplicium.  Burnham and Lewis make no mention of it in their catalogs, nor is it mentioned in the Astronomische Nachricthen for the 1822 to 1824 period.

At any rate, that’s it for the first part of this tour.  Stay tuned for part two . . . . . . . .  and

Clear Skies!  :cool:

Follow

Get every new post delivered to your Inbox.

Join 81 other followers