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Beyond the Weird and Wonderful World of 8 Andromedae: Σ 2987, OΣΣ 244, and OΣ 493

Our last trip concentrated on 8 Andromedae/BU 717 and the area immediately southeast of it, so this time we’ll wander a bit farther afield. But we’ll have to take care that our first leap into the darkness doesn’t take us so far from 8 Andromedae that we cut ourselves off from its gravitational grasp — we’ll need that gravitational tug to pull us back to our starting point so we can reverse the process and leap in the opposite direction.

To get oriented once more, here’s a wide look at the stellar terrain where we’ll spend the night:

Stellarium screen image with labels added, click to enlarge.

Stellarium screen image with labels added, click to enlarge.

As I mentioned in the last post, when you first look up into the sky in this general area, the first stars your eyes will be drawn to are the trio of Iota (ι), Kappa (κ), and Lambda (λ) Andromedae. Our destination is the dimmer array of stars to their north and a bit closer to Lacerta. A reliable way to locate the 11-8-7-3 Andromedae grouping is to follow the arc formed by Iota-Kappa-Lambda as it curves toward the southern tip of Cepheus, but keep your eyes on the south side of that arc in order to pick out 11-8-7-3 Andromedae, which are about a third of the distance to Cepheus. Also, as I mentioned before, you’ll probably catch sight of the trio of 8, 7, and 3 Andromedae first, mainly because 11 Andromedae is noticeably fainter than the other three stars (11 Andromedae glimmers weakly at a magnitude of 5.44, while 3 Andromedae gleams more noticeably at a magnitude of 4.66 – not a lot of difference, but it can be enough to make it difficult to visually pluck 11 Andromedae from the sky).

Once you have 11-8-7-3 Andromedae located, point your finder at 8 Andromedae and you’ll find yourself looking at a scene somewhat like this:

Stellarium screen image with labels added, click to enlarge.

Stellarium screen image with labels added, click to enlarge.

The distance from 8 Andromedae to 11 Andromedae is only 29’, whereas 7 Andromedae is about twice as far at 56’, and since both of those two stars will guide us to where we want to go, we’ll center our finder on 8 Andromedae to get started.

As luck would have it, 8 Andromedae is almost equidistant from our two destinations stars (the ones with the turquoise labels, Σ 2987 and OΣΣ 244), so I’ll flip a coin to decide which direction to go first . . . . . and the winner is . . . . . .  Σ 2987!  Center 7 Andromedae in your finder, scan 30’ to the southwest, and you’re eyes will land on Σ 2987. You’ll notice there’s a tight pair of eighth magnitude stars wedged between 7 Andromedae and Σ 2987 which can be used to keep you on course (the brighter and southernmost of that pair is 7.65 magnitude HIP 114537).

Σ 2987  (STF 2987)     HIP: 114420   SAO: 52795
RA: 23h 10.4m   Dec: +49° 01’
Magnitudes: 7.42, 10.41
Separation:  4.4”
Position Angle: 150°  (WDS 2007)
Distance: 148 Light Years (GAIA)
Spectral Class: A is G1

This is a tough one, so click on the sketch to enlarge it and look for the secondary at about midway between the seven and the eight o’clock position. East and west are reversed here to match the view in the SCT.

This is a tough one, so click on the sketch to enlarge it and look for the secondary at about midway between the seven and the eight o’clock position. East and west are reversed here to match the view in the SCT.

My first trip in search of Σ 2987 was with a five inch refractor and it was spent trying to split a star that wouldn’t split . . . which was because it was the wrong star. Argh! Not everything goes according to plan when you work in the dark.

I came back a second time with the 9.25 inch SCT and a more deliberate plan, and as you can see from the sketch I found the correct star. Thanks to the larger aperture, it didn’t take much magnification to pry the secondary loose from the primary. Whether I could have done that with the five inch refractor is an open question. Theoretically it should be possible on a night of good seeing, but it would require more magnification than the 123x I used with the SCT.

But the ease with which I split what should have been a more difficult pair left me with a suspicion the secondary is slightly brighter than the 10.41 listed for it in the WDS, although I haven’t been able to confirm that by looking at catalog data. Simbad shows a visual magnitude for it of 10.40 (third star in the list, BD+48 3952B), while UCAC4 and URAT1 were no help whatever since neither catalog lists Vmag values for the secondary. The J and K magnitudes shown in UCAC4 for the secondary yield a visual equivalent of 7.625, which is way too bright, probably a result of the primary overpowering the CCD sensors. It’s also possible the separation is greater than the 4.4” listed for the pair in the WDS, but historical data (discussed below) indicates that’s highly unlikely.

However, there is one thing that we can be certain of:  this pair of stars is carving their way through interstellar space in tandem, as this Aladin image with an overlay of Simbad proper motion shows:

Instead of two arrows, we see three of them super-imposed on this image by Simbad. A third object was sensed at 60.07 milli-arcseconds from the primary (note the blue label), but I haven’t found any data identifying that object. More than likely it’s an error of some kind. Click to enlarge.

Instead of two arrows, we see three of them super-imposed on this image by Simbad. A third object was sensed at 60.07 milli-arcseconds from the primary (note the blue label), but I haven’t found any data identifying that object. More than likely it’s an error of some kind. Click to enlarge.

You can see the proper motion numbers at the bottom of the image, which show almost identical motion for the primary and secondary. I ran my own numbers by computing the motion using 1999 2MASS coordinates and 2015 GAIA coordinates which resulted in almost identical numbers for the primary, +236 +051.5, and a slightly different number for the secondary, +249 +034, which shows it diverging somewhat from the path of the primary.

Click to enlarge.

Click to enlarge.

Looking back at the measures I could find on Σ 2987, it’s apparent there’s been little change over the years, provided the first measure listed in the WDS from 1828 is excluded. That one shows a separation of 2.8” and a position angle of 172 degrees, which stands out as an exception to the eight measures listed at the right. Since F.G.W. Struve is credited with discovering this pair, I looked in the only likely source for that measure (Catalogus novus stellarum duplicium et multiplicium) and found only coordinates and magnitudes. Lewis shows Struve with an 1832 measure of 3.45” and 166.0 degrees in the excerpt at right from his book, so the 1828 data listed in the WDS remains rather elusive.

On the other hand, looking at the change in separation and position angle in the eight measures listed, it appears this pair has widened slightly since Struve’s 1832 measure, which is in agreement with the proper motion data I generated from the 2MASS and GAIA coordinates. That could be a possible indication of a very slow and ponderous orbit, or, more than likely, the two stars are just linked by a common physical origin, which is reflected in their motion.

Now to our next pair, OΣΣ 244 (STTA 244), which we’ll find is also accompanied by a second pair, OΣ 493 (STT 493). To catch both of them in the same field of view, return to 8 Andromedae for reference, then center your finder on 11 Andromedae, slide it over to the the north corner of your eyepiece, and you’ll find OΣΣ 244 and it’s two companions near the center of the field of view.  For reference, here’s our last chart again (the unlabeled star perched between 11 Andromedae and OΣΣ 244 is OΣ 493).

OΣΣ 244  (STTA 244)     HIP: 115171   SAO: 52912
RA: 23h 19.7m   Dec: +48° 23’
Magnitudes   AB: 6.41, 10.15   AC: 6.41, 11.50
Separations  AB: 100.6”           AC: 119.2”
Position Angles   AB: 293° (WDS 2009)   AC: 108° (WDS 2009)
Distance: 389 LY (GAIA)
Spectral Classifications: A is K1, B is K2

OΣ 493  (STT 493)     HIP: 115114   No SAO Number
RA: 23h 19.0m  Dec: +48° 30’
Magnitudes: 7.67, 10.66
Separation:  7.6”
Position Angle: 28°  (WDS 2010)
Distance: 786 LY (GAIA)
Spectral Class: A is A8

The primary of OΣΣ 244 is at the center of this sketch, with the B component just outside the glare between the 10 and 11 o’clock position, and the fainter C component on the other side of the primary at the 4 o’clock position. OΣ 493 is seen northwest of OΣΣ 244, but you’ll have to enlarge the sketch to see the difficult secondary in the OΣ 493 inset at the right. East and west reversed to match the refractor view, click to enlarge the image.

The primary of OΣΣ 244 is at the center of this sketch, with the B component just outside the glare between the 10 and 11 o’clock position, and the fainter C component on the other side of the primary at the 4 o’clock position. OΣ 493 is seen northwest of OΣΣ 244, but you’ll have to enlarge the sketch to see the difficult secondary in the OΣ 493 inset at the right. East and west reversed to match the refractor view, click to enlarge the image.

Because it can be seen within the same field as 11 Andromedae, OΣΣ 244 is an easy triple star to find and, thanks to its wide separations and accessible magnitudes, easy to identify. I had to use a bit of averted vision at first to lasso the C component, but once I had it roped into view, I had little problem seeing it in the five inch refractor. It would likely be an averted vision view for the most part in a four inch refractor, and with careful inspection and a dark sky, should be within reach in a three inch or 90mm refractor.

However, OΣ 493 is a bit more difficult because of its tighter separation. I couldn’t pry the secondary out of the primary’s glare with anything less than 148x (an 8mm eyepiece) in the five inch refractor, but with more magnification it should be visible in a four inch instrument. Anything less will be a real challenge, but theoretically, the secondary should be just within grasp of a 3 inch or 90mm refractor with enough magnification and decent seeing conditions.

As the OΣ prefixes indicate, each of these are Otto Struve discoveries. But before we look at the discovery dates, it might help to illuminate the difference between the OΣ and the OΣΣ prefixes. The OΣ prefix applies to the first group of stars in Otto Struve’s 1845 survey Catalogue de 514 Étoiles Doubles et Multiples Découvertes Sur L’Hémisphère Céleste Boréal par La Grand Lunette de L’Observatoire Central de Poulkova. Those stars were limited to separations of 32” or less, except when the secondary was fainter than magnitude 9.5, in which case the separation was limited to 16” – which in fact, is the majority of stars in that section of the catalog. Pairs with larger separations than those just described were placed in the second section of the catalog (frequently referred to as the Appendix) and were assigned prefixes of OΣΣ.

OΣ 493 was discovered in 1847 and initially measured with a position angle of 26 degrees and a separation of 8.1” When compared with the most recent WDS measures (2010), there’s been very little change in the intervening 163 years, which is not at all surprising considering the primary’s distance of 786 light years as measured by GAIA.

Click to enlarge.

Click to enlarge.

The more interesting of the two stars by far is OΣΣ 244, not only because it’s wider and has an additional component, but because the primary has considerable proper motion. The WDS shows the first recorded measure of the AB pair took place in 1875, but it was discovered by Otto Struve prior to that date, probably at the same time he first saw OΣ 493. His listing for OΣΣ 244 in the second half of the 1845 catalog doesn’t contain an observation date or any measures (the catalog page can be seen at the end of this post), which is why the first date cited in the WDS is 1875. S. W. Burnham credits Dembowski with that measure, which can be seen in the except above from Burnham’s 1906 catalog (the Greek symbol Δ is used for Dembowski). The AC pair was first measured in 1903 according to the WDS, but there’s no mention by Burnham of the C component in the catalog entry above, which is an indication the discoverer was someone other than Burnham.

When you compare the first measures of the AB and AC pairs with the most recent WDS data, it’s evident one of the three stars is moving fairly rapidly in comparison to the other two stars:

AB in 1875:  78.9”, 305°         AC in 1903: 137.8”, 104°
AB in 2009: 100.6”, 293°        AC in 2009: 119.2”, 108°

As I mentioned above, the cause of those very noticeable changes in relative positions is the proper motion of the OΣΣ 244 primary, which is illustrated below in an Aladin image with Simbad’s proper motion data overlaid on it:

It’s true – a picture is worth a thousand words! Simbad’s proper motion data is at the bottom of the image in the columns labeled PMRA and PMDEC, and the super-imposed arrows on the individual stars are proportional to that data. Aladin image with Simbad data and additional labels, click to enlarge.

It’s true – a picture is worth a thousand words! Simbad’s proper motion data is at the bottom of the image in the columns labeled PMRA and PMDEC, and the super-imposed arrows on the individual stars are proportional to that data.  The blue arrows on the B and C components are difficult to see, so click to enlarge the image. (Aladin image with Simbad data and additional labels added).

Again, for those not familiar with the way the proper motion data is presented, each of the numbers in those two columns represents thousandths of an arc second. So the first number in the PMRA column, which reads 206.29 is actually .20629”, and the number next to it in the PMDEC column, 31.3, is actually .0313” (multiply each number by .001). The absence of a plus or a minus sign indicates eastward motion in right ascension (RA) and northward motion in declination (DEC) (sometimes a “+” sign appears in front of the number in those cases, but it’s been left out here). A negative sign in front of the values indicates westward motion in RA and southerly motion in declination.

Frequently you’ll see the proper motion data is rounded to just three places, and the RA and Dec numbers are presented as a pair of three digit numbers.  For example the WDS would list the numbers I mentioned above for the primary as +206 +031, the B component values as -007 -020, and the C component values as +019 +008.

Of course, you don’t need to know all of that to enjoy the celestial sights above, but on the other hand, when you peel back the outer layer of the heavens, you’ll find the secrets of the universe begin to reveal themselves one at a time. It’s always just a bit humbling to realize that vast vault of stars over our heads are constantly in motion relative to each other, even if it’s only at a snail-like pace of one thousandth of an arc second at a time. Change is constant, even when it’s imperceptible – and time is relative to the scale on which it occurs.

Clear Skies and tolerable temperatures! 😎

Page 56 of Otto Wilhelm von Struve's 1845 Catalog. STTA 244 is the seventh star from the bottom of the page. Click to enlarge.

Page 56 of Otto Wilhelm von Struve’s 1845 Catalog. STTA 244 is the seventh star from the bottom of the page.  The numbers in parentheses in the right hand column are estimated magnitudes.  Click to enlarge.

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The Weird and Wonderful World of 8 Andromedae: BU 717, ES 2725, and ARY 3

On one of those crisp September nights when I was lingering in Lacerta over delicately separated double stars and diminutively defined open clusters, I happened to look away from the eyepiece just long enough to catch sight of an arc of three faint stars lined up on the Andromeda side of Lacerta (as opposed to the Cygnus side — see chart below).  Puzzled because I had never noticed them before, I flipped open my dog-eared copy of Sky and Telescope’s Pocket Atlas to Chart 72 and identified the three stars as Iota (ι), Kappa (κ), and Lambda (λ) Andromedae. I noticed the three stars were devoid of double star designations (although Kappa is most definitely a multiple star that goes by the designation HJ 1898), but my wandering eyes were quickly drawn a few degrees north to another concentration of stars curving towards Lacerta, which were labeled as 11, 8, 7, and 3 Andromedae. And that subtle little international double star symbol — a line drawn through the dot of a star on a star chart – that short line that makes the heart of every double star enthusiast skip a few beats and then pulsate as wildly as Sirius when its five degrees above the horizon . . . well, let’s just say that horizontal splash of line split more than a few dots of stars.

In other words, a veritable double star feast before my very eyes.

But before we dine on double stars, first we need to take a careful look at this area, because it’s very easy to mistake the Iota (ι), Kappa (κ), and Lambda (λ) trio for our destination, which instead is the threesome of 11, 8, and 7 Andromedae.

Stellarium screen image with labels added, click to enlarge.

Stellarium screen image with labels added, click to enlarge.

When you first cast skyward eyes on the general area at the center of this chart, Iota (ι), Kappa (κ), and Lambda (λ) Andromedae catch your gaze first because they’re brighter than 11, 8, and 7 Andromedae. The first three stars have magnitudes of 3.82, 4.14, and 4.29, respectively, whereas the last three are notably fainter at magnitudes of 5.44, 4.86, and 4.53, again, respectively. But if you follow the arc formed by Iota (ι), Kappa (κ), and Lambda (λ) as it curves toward the southern edge of Cepheus, you’ll find it takes you right over the top of 11, 8, 7, and 3 Andromedae.

Again, you have to be careful here because your eyes are likely to miss the first of that group, 5.44 magnitude 11 Andromedae, and instead will be drawn to 8, 7, and 3 Andromedae, that last one’s 4.66 magnitude being distinctively brighter than 11 Andromedae. But once you point a finder at 8 Andromedae, the middle star of the trio we’re concentrating on, you’ll find 11 and 7 Andromedae become distinct — as the chart below shows:

Stellarium screen image with labels added, click to enlarge.

Stellarium screen image with labels added, click to enlarge.

We’re going to take a look at a total of six double and/or multiple stars in this area, so to keep the length of this thing from getting out of control, I’ll divide our excursion into two parts. This first part will look at 8 And, ES 2725, and ARY 3.

8 Andromedae also goes by the double star designation BU 717, and that’s where we’re going to start – and also where we’re going to find a mysterious surprise.

BU 717  (8 Andromedae)  HIP: 115022  SAO: 52871
RA: 23h 17.7m   Dec: +49° 01’

Identifier Magnitudes Separation PA WDS
BU 717 AB: 5.01, 13.00 7.8” 160° 2015
BU 717 AC: 5.01, 10.83 217.3” 131° 2008
FOX 273 AD: 5.01, 12.46 58.6” 233° 2007
WAL 147 AE: 5.01, 12.34 97.9” 107° 1903
KUI 116 AF: 5.01, 16.00 14.6″ 179° 2015
KUI 116 BF: 13.00, 16.00 7.6” 200° 2015

Distance: 563 LY (Simbad)
Spectral Class: A is M2

Once you get past the irresistible orange glow of the primary, the companions to look for are C, D, and E. The secondary, B, is irretrievably buried in primarial glow (thanks to the eight magnitudes of difference between A and B at a distance of 7.8”), and with the F component hampered by a magnitude of 16, it’s well out of reach. (East and west reversed in this sketch to match the SCT view, click for the larger version).

Once you get past the irresistible orange glow of the primary, the companions to look for are C, D, and E. The secondary, B, is irretrievably buried in primarial glow (thanks to the eight magnitudes of difference between A and B at a distance of 7.8”), and with the F component hampered by a magnitude of 16, it’s well out of reach. (East and west reversed in this sketch to match the SCT view, click for the larger version).

I’ve looked at 8 And/BU 717 with both a five inch refractor and the 9.25 inch SCT used for the sketch, and in each case I had little problem digging C, D, and E out of the rich orange glow of the primary, although I had to call on averted vision to pry D and E out of the sky in the five inch refractor. BUT – despite this apparent cooperative beginning – I was confronted with a perplexing problem when I first peered into an eyepiece and started identifying components.

Where in the world is WAL 147???

On the night I first glued my observing eye to 8 And/BU 717, the AE pair (WAL 147) was listed in the WDS with a distance of 57.1” at a position angle of 89 degrees. For the sake of relative spatial comparison, I had the AD pair (FOX 273) which the WDS showed parked at a distance of 58.6” from the primary. So with both the D and E components having (supposedly) similar separations, and E (supposedly) parked almost right at 90 degrees, I knew exactly where to look – and there wasn’t anything there. That spot was simply empty, unoccupied, vacant – devoid of stellar light, in other words. So where in the astronomical world was WAL 147?

I had also noticed the magnitudes of D and E were very similar, 12.46 for D and 12.34 for E, so I began scanning for a star similar in magnitude to D – and I found one, parked a bit further south of the 90 degree position and at almost double the distance listed in the WDS. But that distance caused skeptical alarm bells to shatter the peace and quiet of the night, so after carefully sketching the position of that star in relation to all the others, I retired to a drier, warmer, and more comfortable spot in front of a computer, pulled up an Aladin image of BU 717 on a computer screen, and went to work.

Aladin allowed me to do two things – check the magnitude of the star I flagged as a possible candidate for the E component, and measure its distance and position angle.

To avoid confusion, I’ve flipped the Aladin image to match my sketch of BU 717 above, so west is at the left and east at the right. Aladin image with data and labels added, click to enlarge.

I’ve labeled the C, D, and E components in the image above, and below the image I’ve added the WDS data which was current at the time I sketched BU 717. Notice the measures for AE are shown as 57.1” and 89 degrees – that spot is labeled in the image with an “X”. You can see a star near that location which is shown with a magnitude of 17 in the URAT1 catalog, which is far too dim to be a candidate for the 12.34 magnitude WDS companion, and of course was well out of the reach of both of my telescopes.

Also shown to the right of the WDS data are the measures I plotted using 2015.0 GAIA coordinates, which in the case of the C and D components differ somewhat from the older WDS data. After I sent my findings to Bill Hartkopf at the USNO/WDS, he established a separation of 97.9” and a PA of 107 degrees for the AE pair, which is both wider and a bit more southerly than what I came up with using GAIA data. However, that data is based on a 1903 measure (probably from a photographic plate), which is now the only observation and measure listed in the WDS for WAL 147. Prior to sending my findings to the WDS, there were observations dated 1944 and 1998, which can be seen in the WDS data beneath the Aladin image above, so it appears there was some kind of error associated with that particular WDS data.

18-5-inch-clark-refractor-at-dearborn-observatory

Click to enlarge.

In case you’re wondering about how that difficult B component we couldn’t see was pried out of the primarial glare, S.W. Burnham managed it in 1887 with the 18.5 inch Clark refractor at Dearborn Observatory (shown at right), which at the time was attached to the University of Chicago. Philip Fox added the C component in 1915, also while using that same refractor.

Now we’ll leave the weird world of 8 And/BU 717 and move on to our last two stars, which agreeably can be seen in the same field of view. This isn’t going to be a difficult move since all we’re going to do is nudge 8 And over to the west corner of our field of view until the similarly-hued 11 And appears in the southern corner of the view. That will put ES 2725 close the center of your field of view and ARY 3 will appear in the southeast corner of the eyepiece, just a bit more than 10’ northeast of 11 Andromedae.

ES 2725     HIP: 115128   SAO: 52899
RA: 23h 19.1m   Dec: +48° 55’
Magnitudes   Aa, Ab: 7.35, 11.20    AB: 7.27, 8.62
Separations   Aa, Ab: 0.5”              AB: 54.1”
Position Angles:  Aa, Ab: 170° (WDS 1991)   AB: 235° (WDS 2013)
Distance  A: 417 LY (GAIA)    B: 1173 LY (GAIA)
Spectral Classes:  A is A2, B is G5
Note: Aa, Ab is HDS 3321, AB is ES 2725

ARY 3     No HIP Number    SAO: 52929
RA: 23h 20.7m   Dec: +48° 48’
Magnitudes: 8.96, 9.47
Separation:  118.1”
Position Angle: 210°  (WDS 2010)
Distance  A:  232 LY (GAIA)    B: 421 LY (GAIA)
Spectral Classes:  A is G5, B is F8

ES 2725 is the pair of stars at the very center of this view, tilted at about a forty-five degree angle (and identified in the box at the right). ARY 3 is the fainter and wider pair at the southeast edge of the view (18’ southeast of ES 2725 and on a line with BU 717 and ES 2725), tilted more noticeably to the north than the ES 2725 pair. (East and west reversed to match the refractor view, click on the sketch to bring it to life).

ES 2725 is the pair of stars at the very center of this view, tilted at about a forty-five degree angle (and identified in the box at the right). ARY 3 is the fainter and wider pair at the southeast edge of the view (18’ southeast of ES 2725 and on a line with BU 717 and ES 2725), tilted more noticeably to the north than the ES 2725 pair. (East and west reversed to match the refractor view, click on the sketch to bring it to life).

Now I know these aren’t the most stunning double stars ever to grace an eyepiece, but since we didn’t have to wander far to find them, we may as well pay them the courtesy of a visit. And with a minimal investment of time, we can even mine a few morsels of information from them. For example, according to GAIA’s data, the A and B components of ES 2725 have 756 light years of distance between them. And the ARY 3 pair are considerably less distant from each other with 189 light years of interstellar space wedged between them. That would make each of them an optical pair, although that doesn’t necessarily apply to the Aa Ab pair of ES 2725, since there’s no data on the distance of that 11.20 magnitude companion sitting half an arc second from the primary.

Not surprisingly, if we look at how they’re moving through interstellar space, we’ll also find there’s no shared motion between each of the pairs.

Aladin images with labels added, PM vectors plotted by Aladin. Click to enlarge.

Aladin images with labels added, PM vectors plotted by Aladin. Click to get a much better view of the directional arrows.

In case the PM numbers at the bottom of the image mystify you, the first of each three digit pair of numbers is the motion in right ascension (east or west) and the second is the motion in declination (north or south). The numbers represent thousandths of an arc second, and the plus sign denotes northerly or easterly motion, whereas the negative sign signifies westerly or southerly motion.

So in the case of ES 2725, the A component is moving east in right ascension at the rate of .078” per year and north in declination at the rate of .008” per year, and the B component is moving east at the rate of .022” per year and north at the rate of .011” per year.  Notice the rate of motion of the primary is greater than that of the secondary, which is not a surprise when you look at the individual distances in the data line above and find the secondary is farther away from us (1173 light years for the secondary, 417 light years for the primary).

The primary of ARY 3 is also moving east and north, but its secondary is moving in the opposite direction at the rate of .042” per year west and .068” per year south. In each case, the arrows correctly indicate the combined direction (right ascension and declination) and the combined rate of motion for each of the components.  Also notice the rate of motion of each of these stars matches well with their distance when compared with the ES 2725 pair.

So there you have it – just enough data about ES 2725 and ARY 3 to tell you more than you knew before you got to this point! You can even pass it on to your friends and neighbors. They’ll either be totally amazed or they won’t speak to you again in public.

Either way, don’t despair, because we’re going to stay in this immediate vicinity for our next trip. We’ll look at three more double and/or multiple stars . . . and who knows what arcane details of stellar motion we’ll uncover next.

Clear Skies! 😎

Almach: A First Approach

In the early morning hours of August 25th, 1779, as the first glimmering rays of the new day are just beginning to cast their long, faint-fingered light into the eastern sky, William Herschel is bent over an eyepiece, waiting for his last star of the night to drift into view.  He’s been at this since nine o’clock the previous evening without a break.  The air is damp and cool, his coat is barely keeping up with the falling temperature, he’s hungry and tired, and his eyelids are beginning to sag as sleep begins its inevitable persistent tug at them.

As that last star finally begins to drifts lazily into view in the eyepiece, William suddenly sits up straight and erect in his chair ———- and in awed shock and surprise, his native language takes charge:

“Ach!  Eine enge Paar von Sternen!  Sie sind rot!  Nein, blau!  Nein, nein . . . . .
.         (A close pair of stars!  They’re red!  No, blue!  No, no . . . .)
the large one is red, the small one is blue!  It’s sky blue!  A light sky blue!
Ach, nein, it’s ‘inclining to green!’  It’s . . . . . it’s . . . . . ist eine . . . . . eine . . . . .
it’s. . . . . . . . ‘A most beautiful object!’ ”                              (p. 69 of the 1782 catalog)

He takes a quick measure of its separation, turns to his observation log, and writes: Class III, number 5.

.

It’s November 29th, 1821.  Under a dome in London, the metallic creaks and wooden groans of a large equatorial mount echo from the walls as John Herschel and James South slough the five foot long tube of a 3.8” Dolland refractor to a right ascension of 1h 53m and a declination of +41° 28’.  Their target is Sir William’s “most beautiful object.”  Even though each of them has seen Almach several times before, their eyes are still riveted to it as they take turns at the eyepiece.

“What color do we ascribe to the large one, John?”
“Orange.”
“And the small one?”
“Mmmmm  ——-  let’s . . . . . . . . yes, let’s describe it as emerald green.”
“Anything else?”
“Yes, we have to include this: ‘very beautiful.’ “

And then at the top of the page, the future Sir James South adds their catalog number,  XXVI  . . . . . .  and leaps to the eyepiece.                       (p. 49 of Herschel/South Catalog)

.

" . . . Among the best of all . . . is the last star of the string of bright beauties that helps make the constellation Andromeda, second magnitude (2.16) Almach, Andromeda's Gamma star."   (Stellarium screen image with labels added, click to enlarge).

” . . . Among the best of all . . . is the last star of the string of bright beauties that helps make the constellation Andromeda, second magnitude (2.16) Almach, Andromeda’s Gamma star.” (Stellarium screen image with labels added, click to enlarge).

 Almach  (Σ 205)  (H III 5)  (SHJ 26)               HIP: 9640   SAO: 37735
RA: 02h 03.9m   Dec: +42° 20′
.                              Magnitudes       Separation      Position Angle        WDS
STF 205    A, BC: 2.31,   5.02              9.50″                     63°                  2011
BAR 22          AD: 2.31, 15.00            27.90″                  245°                  1898
STT 38           BC: 5.10,   6.30              0.17″                     96°                  2012
Distance: 355 Light Years
Spectral Classifications:  A is K3    C is B8
Status: A, BC is physically linked; BC is gravitationally linked, a view of the orbit can be seen here.

OK, you’ve just read the origins of the second and third numbers in parentheses above – and the question taking shape in your mind is this:  Is Almach really that good?

A sight that will stir your soul on a cold winter night!  (East & west reversed to match the refractor view, click on the sketch for a larger version).

A sight that will stir your soul on a cold winter night! (East & west reversed to match the refractor view, click on the sketch for a larger version).

You bet your last little Ortho it is.

Look, even Jim Kaler waxes eloquently about it:

You take your new telescope to the back yard perhaps wondering what to examine. When finished with the Moon and the bright planets you turn to the stars, first perhaps to the grand Orion Nebula, next maybe to the magnificent Andromeda Galaxy. Then it is time for double stars. The sky abounds with them . . . Among the best of all . . . is the last star of the string of bright beauties that helps make the constellation Andromeda, second magnitude (2.16) Almach, Andromeda’s Gamma star.”

Almach’s gift to the visual observer is enticingly wrapped in its vividly contrasting colors.  You can’t fail to be impressed by them, regardless of what aperture you might happen to have hanging around your house, your back yard, or your observatory.

Of course there are other attractively tinted stars traveling every night through the clear skies above us, and every one of us has his or her favorite.  I’ll just say that Almach is very, very high on my very, very crowded list of favorites.  And I’ll add this: it’s contrasting red/orange and pale blue/emerald green is a sure cure for whatever ails your frazzled ocular nerves.

But as is frequently the case when confronting true beauty, there’s more than meets the eye.  Almach is not just another pretty pair of stars —–  it’s also a pretty complicated collection of stars.

If you look at the data line above, you’ll see three separate identifiers listed for Almach’s components.  The second of those, BAR 22, is a rather mysterious 15th magnitude star which was first observed in 1898 by Edward Emerson Barnard and hasn’t been observed since.  So we’ll set it aside for now while we look at the others —- although if you happen to have the aperture available to chase it down, please do.  I would be more than interested in hearing about it since E. E. Barnard was not well known for his double star discoveries.

Let’s focus instead on the BC pair, which you’ll see listed twice.  The first time is opposite STF 205, where you’ll see it included with the primary as “A, BC”; and the second time is opposite STT 38, where it’s listed separately – and with a very tight separation between “B” and “C” of 0.17 seconds of arc.

It was Otto Wilhelm von Struve who first pulled back the optical veil drawn over “B”.  His sighting of “C” took place in the autumn of 1842 when the two stars were separated by roughly 0.5 arc seconds, but it took a while for that information to filter through the slow-flowing astronomical channels of the era.

Let’s park ourselves in Admiral William H. Smyth’s parlor in the late spring of 1843 and listen to him describe history as it was taking place:

.

. . . Mr. Baily put into my hand a letter which he had received from M. Struve, in October, 1842, announcing the unlooked for tidings that he had detected γ Andromedæ to be triple, and that the companion is composed of two stars of equal size, separated by an interval of less than 0″·5.  I lost no time in notifying this to my friend Mr. Dawes, who, as well as myself, had so repeatedly gazed at this, merely as a double star.  On the 1st of November, he informed me that he charged Mr. Bishop’s refractor with an excellent single lens magnifying 520 times, and when the star was best defined, became satisfied of an elongation sf and np [south following and north preceding] in the companion, making it look like a dumpyish egg.  By the measures he obtained, the angle of position was 125° 48’, and the distance of the centres was estimated at 0″·4.  I also received a letter from the Rev. J. Challis, under date of December 9th, 1842, after his attacking it with the Northumberland equatoreal, at my request, of which the following extract is most interesting.

‘I looked at γ Andromedæ the first opportunity after receiving your note, and was surprised to find that I could easily recognize the small star as being double.  I cannot say that I saw the components separated, but there was a decided elongation, and several measures which I took of position agree well with each other.  The distance is certainly not more than 0″·5.  My impression was, that the components are not equal.’

When I repaired to Hartwell, in February, 1843, I was baffled in my attempts to examine this object in the evening twilight.  But on returning thither in the spring I was enabled to catch some fine early views of it.  On the 1st of May, the morning atmosphere was perfectly diaphanous, and I teased γ under various powers from 118 to 600, until I fairly saw that the comes was not round, but elongated, in a direction np and sf  to the amount above estimated.  It was, however, so slightly oval, that, but for M. Struve’s unexpected announcement, I must assuredly have overlooked it.”
.                                                                            pp. 50-51 of The Bedford Catalog)

.

Now, when I first looked up the statistics for Almach in the Washington Double Star Catalog (WDS), the separation of the BC pair was listed at 0.51″, so my initial reaction was to forget about any telescopic attempt to see it.  But after reading of the Admiral’s experience, and taking into account the aperture of the instrument he used, I had second thoughts on the matter – and here’s why:

Admiral Smyth employed a 5.9” (150mm) f/17.3 Tulley refractor in his observatory – and normally I wouldn’t associate a six inch refractor with use on a pair of stars separated by only 0.5”  But even more surprising, the telescope referred to by the Reverend DawesMr. Bishop’s refractor — employed a significantly smaller 3.75” (96.5mm) f/15.8 objective made by Dolland.  Those dimension, 96.5mm and f/15.8, also describe the telescope John Herschel and James South were using on Almach on November 29th, 1821, although they didn’t use enough magnification to glimpse an elongation of “B.”  But please take careful note –- these are early 18th century long focus achromatic doublets, very distant relatives to today’s short focus exotic-glassed apochromatic refractors – and obviously very capable double-star instruments.

So I aimed my six inch f/10 refractor at Almach a few nights later and stepped my way up to 1140x (a 3.2mm TMB Planetary eyepiece lodged in 2.4x Dakin Barlow), which is an absolutely unheard of magnification for either me or that scope.  And when I didn’t see the first hint of elongation – even though surprisingly the image was actually quite viewable – I decided I had better check the orbital elements data from the WDS.    And that’s when I discovered the 2012 separation for the BC pair  was actually a much tighter — and very much out of reach — 0.172 arc seconds.

So all I have to do now is wait until about 2045 for the separation to widen to 1.5”.  Stay tuned.  😉

There’s one more exotic addition to the Almach family that deserves momentary mention:  it seems that the “B” of the BC pairing is also double!  It took a spectrograph to detect it – and it revealed a very close and fast orbit of 2.7 days.

At any rate —– when your eyes light on Almach’s magnificently tinted rays, remember all that heavenly color is emanating in your direction from four stars, two of which are hidden from your sight – not to mention that 15th magnitude “D” companion, which may or may not exist in the dark depths of Almachian space.

In Jim Kaler’s words:  “The naked-eye star we know as Almach is thus quadruple, making it a feast for both the mind and for the eye.”

And as we’re about to see, a feast it most certainly is.

Meanwhile, back in our galaxy – Σ79

In November who can resist M31, the Great Andromeda Galaxy, high in the east?  But when you exhaust yourself from all that travel – afterall, even at light speed we’re talking 2.5 million years on the road  – you can return to “home” by sauntering over to Σ79, a wonderful little double about 4-5 degrees northeast of Andromeda and right on a line from the great galaxy to fourth magnitude Phi Andromeda.

Σ79
RA: 1h 00.1m   Dec: +44° 43′
MG: 6.0, 6.8   Sep: 7.8″   PA: 193°
Distance: 420 LY
Spectral Classification: B9.5V, A2.V

That said, I didn’t find Σ79 as easy to find as the description implies.  This is a pretty busy section of sky and part of my problem was I was using M31 as a pointer, telling myself that all I had to do was go roughly north along a line suggested  by the longer axis of M31.  It looks obvious on the charts and I thought it would be obvious in the scope, but finding that longer axis precisely  in the scope proved more difficult than I anticipated. As a result I was looking a bit west of where I should be and targeting the wrong sixth magnitude star and wondering why it didn’t split! In fact I did that more than once because there are four magnitude 6 stars within about two degrees of Σ79! I think I tried to split each one before I finally settled on the one farthest east – the correct one.

What I should have done is gone northeast from Andromeda – technically the PA from M31 to Σ79 is 41° –  and what would have helped immensely is to just draw a line between the galaxy and fourth magnitude Phi Andromedae.  Σ79 falls just east of that line about three degrees south of Phi and almost five degrees northeast of M31.  Here’s a chart from Stellarium that should help.

Click on image for larger version. (Prepared from Stellarium screenshot.)

When scouting this region with 15X70 binoculars I picked up a wonderful cascade of 7th and 8th magnitude stars just to the north, while a shorter cascade actually leads to Σ79, though I didn’t realize that at the time. It really does pay to study – not just glance at, but study – the charts in advance. Would have saved me some time – but then, time prowling a starry sky is never relly wasted 😉

So – arriving at Σ79 my color imagination was working overtime and I saw a wonderful primary I pegged as pale yellow and a secondary I felt was violet. Haas has them as “pearly white and pale blue-violet” in heer “double stars for small telescopes” book.  I have to admit, her colors certainly fit the spectrums better than mine. Not sure where that yellow came from. I was using a 127mm Meade AR5 achromat with a 24mm Panoptic and got a delicate split at 49X. The view was much more satisfying with a 13mm Nagler (90X).  However, I enjoyed the view in the 60mm Tasco better – the power drops to about 42X when using the 24mm Panoptic in this old F16.7 achromat, but the view is one to kill  for – especially with the 13mm Nagler. OK – that’s a judgment call.  I always love the view in the 60mm as long as the doubles are bright enough, and int his case they produced two, absolutely clean, bullet holes in the velvet blackness of night – side-by-side and close, not just in spacing, but in brightness.  I love it!

In fact, I got so enthusiastic about the view in the 60mm I had to push my luck and try the 50mm Stellarvue Sparrow Hawk I was using as a finder. It’s fvertyf ast – about F4 – and I got 40X out of it – about its effective maximum –  by using a 5mm Tak LE. Pristinely delicate and absolutely charming!

OK – maybe seeing was especially good. Maybe I’ve just looked at too many double stars. I’m not at all sure this would have thrilled a visitor to my little observatory. Heck, I’m not sure they even would have seen the split.  But it’s the sort of thing I really enjoy. Σ79 is a keeper. I like the region. And it blows my mind to be looking one moment at a few hundred billion stars 2.5 million light years away, then barely moving your scope to zoom in on something a mere 400 light years away. Those are the sorts of things that keep me coming back to a double like Σ79.

At the Top of the Sky: Alpha (α) and Eta (η) Cassiopeiae; 59 Andromedae

A week ago at this time of night (about 11 PM), the temperature stood at a very warm and dry eighty-two degrees, but tonight it’s a comfortably cool fifty-three.  Fall is definitely hovering in the air, and the autumn constellations are now beginning to take over the eastern sky by midnight.  The cool, crisp temperatures almost have me convinced it’s September already.

Six inch f/10 refractor captured taking a break in the house. The scope on top is a 60mm f/15 using a Carton lens. Click on the image for a larger view!

Tonight, in addition to my usual four-legged companion keeping me company at my feet, there is a waxing slice of moon halfway on the way to being full looking over my right shoulder as I begin to explore the Cassiopeia area.  I can use the moonlight tonight because I’m wrestling with a long six inch f/10 refractor on a large non-computerized equatorial mount.  My navigation tools are two pairs of eyes (my dog has the other pair), a Telrad, and a 60mm f/15 refractor mounted on top of the six inch.

From my observing area, the northern sky is blocked by several large fir trees, which means Cassiopeia has to be close to it’s highest point in the sky before it comes into view.  So at midnight that means it’s distinctive “W” formation is standing almost on edge as I face toward the north.  As I look up at the constellation, Beta (β) stands highest in the sky, with Alpha (α)and Eta (η) arrayed underneath it.

Alpha (α) and Eta (η) Cassiopeiae are at the top left on this chart, 59 Andromedae is at the lower center. For a larger view, click on the chart. (Screen image from Stellarium with additional labels added)

Splitting Tools: Both Eta (η) Cass and 59 Andromedae are great 60mm doubles, and the secondary of Alpha (α) Cass is also visible in a 60mm provided you look closely.   Eta (η) especially is a beautiful sight in a 60mm scope, as can be seen in the sketch below, which was done with a 60mm refractor.

Alpha (α) Cassiopeiae  (Schedir)  (H V 18)  (h 1993)
HIP: 3179    SAO: 21609
RA: 0h 40.5m   Dec: +56° 32′
Magnitudes: 2.4, 9.0
Separation:   71.2″
Position Angle: 281°   (WDS 2010)
Distance: 228.5 Light Years
Spectral Classification: K0
Status:  Optical pair

    Look closely to see the 9.0 magnitude secondary! (East & west reversed to match the refractor view, click for a larger version)

Look closely to see the 9.0 magnitude secondary! (East & west reversed to match the refractor view, click for a larger version)

Alpha (α) Cass, or Schedir, is a beautiful sight in the six inch scope.  The primary is a deep yellow, and the much fainter secondary is just a pinpoint of light well separated from it at 76x.  In the 60mm scope at 54x, I don’t see the secondary at all until I glance off to one side of the primary, and then it pops into view over on the other side.  There is a difference of 6.6 magnitudes between the two stars, so the secondary tends to be lost in the glare of the primary, and tonight there is a bit of moisture in the air which is also being illuminated by the glare.  With some perseverance, I find I can pick out the secondary with direct vision in the 60mm.  But not for very long, though – it has a tendency to disappear within a few seconds.  The Haas book notes that other observers have described the secondary as “purple”, as well as “pale garnet.”  Haas describes it as almond brown.  BROWN???? Granted, star colors can be a very subjective thing, but I can’t say I’ve ever seen a star that comes anywhere close to brown!   In that glare, all I can say is the secondary is a bright pinpoint of pale white light.   I’ll keep an eye out for brown dwarfs, though.

Eta (η) Cassiopeiae  (Σ 60)  (H III 3 — AB only)    HIP: 3821    SAO: 21732
RA: 00h 49.1m   Dec: +57° 49′
Magnitudes    AB: 3.5, 7.4     AE: 3.5, 10.2    AH: 3.5, 8.4
Separation     AB: 13.3″         AE: 79.3″           AH: 684.7″
Position Angle   AB: 322° (WDS 2012)   AE: 125° (WDS 2011)   AH: 355° (WDS 2000)
Distance: 19.4 Light Years
Spectral Classification: G0, K7 (Kaler) or MO (WDS)
Status: AB is physical, orbital chart and data can be seen here

The luscious gold and orange of Eta (η) is one of the most stunning sights in the sky! (East & west reversed again, click to enlarge)

The luscious gold and orange of Eta (η) is one of the most stunning sights in the sky! (East & west reversed again, click to enlarge)

Eta (η) is another pretty sight in the six inch.  The primary is a deep yellow-gold, and the secondary is a small orange-white dot standing out near it at 76x.  In this case, I think I prefer the view in the 60mm scope because the two stars are closer together.  But I linger over the sight of this pair in both scopes for about twenty minutes before moving on.   After all, I’m not in a hurry — the cool air is invigorating, the moonlight is splendid, the rumble of the ocean in the background is soothing — and the view in both scopes of these two white stars silhouetted against the black sky is hard to give up!

59 Andromedae  (Σ 222)  (H IV 129)       HIP: 10176    SAO: 55331
RA: 2h 10.9m   Dec: +39° 02′
Magntiudes:  6.1, 6.7
Separation:   16.6″
Position Angle:  36°  (WDS 2011)
Distance: 263 LY
Spectral Classification: B9, A1

Before I quit for the night, I move the scope over to Andromeda to get a look at Almach, which Greg has written a very nice description of here.  After being awed by it’s deep gold and blue, I check the Haas book to see what else is in the vicinity and come up with 59 Andromedae, which lies about halfway between Almach and Beta (β) Trianguli.  I navigate to it via the old naked eye trick by picking out 58 Andromedae, as shown in the map, and then I’m barely able to detect the presence of 59 just to the north of it.  Even at it’s dimmest setting, though, the Telrad tends to blot it out, so I aim into the general vicinity, peer into the eyepiece, and find two closely spaced white stars of similar brightness staring back at me.  At 76x in the six inch, the twin white globes almost look as if they’ve been painted onto a black background sky.  But again, I find I prefer the view in the 60mm scope simply because the two stars are closer together.  And once more, Haas is poetic in her description of the colors: “pearly white and peach white.”

These observations were made just after midnight on the cool and crisp morning of August 20th, 2010, with a cup of tea for me and a Milk Bone for Astro Dog Klaus.

“Woof!”

(WDS data updated 4/14/2013)

Almach: GOLD and blue; Albireo: BLUE and gold – Both: priceless!

Splitting Tools for Almach: Yields easily to 50mm scope at high power.
Splitting Tools for Albireo: Yields easily to 50mm scope at low power.

Gamma Andromedae – Almach
RA: 02h 04m Dec: +42°20′
Mag: 2.16, 5.0 Sep: 9.7″ PA: 63°
Distance: 355 ly
Spectral type: K3, B8

Beta Cygni – Albireo
RA: 19h 31m Dec: +27°58′
Mag: 3.4, 4.7  Sep: 34.7″ PA: 55°
Distance:  380 ly
Spectral type: K3, B0

Well, that’s how they hit me this morning. You may think I mean these famous pairs of stars are the same. Oh no! Far from it. I mean that Almach – the “fall Albireo” in my book – is gold and blue with the emphasis on gold.  And Albireo – the real thing – the original – the one and only –  is, well, blue and gold, for it’s the intensity of the blue that strikes me. I was glad to see this subjective impression is borne out, at least in part, by the spectral class designations, but, of course, color perception is a very subjective business and there are several other factors that make your overall experiences of these two “60mm jewels” different, including separation, magnitude range, and ease of finding.

Oh – and before saying more – both of these are really triples – but I don’t know anyone who has split either visually, the third star being so close. So as far as the typical visual experience goes, they are doubles – though in your minds eye you can see more – much more.

I think I caught them both under pretty identical conditions, though, one climbing up the eastern sky, the other diving down in the west.  I could quickly swing from one to the other in the growing morning twilight. At 4 am Almach was at 50 degrees altitude, Albireo 52 degrees – with Albireo having slightly darker skies for being in the west – but then, I had begun my observation of Almach 15 minutes earlier when the skies in the east were somewhat darker.

It’s my 69th birthday and these old friends had come to the  party which began at 3:30 am when I stepped out on the rear deck to find delightfully clear skies. Five hours earlier I had gone to bed to intermittent clouds and I really expected clouds this morning. But here was the Milky Way and I did my best to  hurry the 60mm Unitron 114 out the door – I leave it set up in the library – grab eyepiece case and observing chair, and even nuke a cup of tea, all without disturbing my night vision. (Yes, when you wake up in a darkened bedroom your night vision should be pretty good – mine is. The trick is to do what you have to do without ruining it. Sometimes I plan ahead for this by leaving red goggles next to my bed, but I hadn’t this morning.)

I’d like to say I got right down to business, knowing  I was already entering astronomical twilight, but I just had to try the 60mm on the Andromeda Galaxy first and to my delight, the 32mm Plossl gave me a wonderful  view of M31 with M32 jumping out immediately and almost as quickly, M110! That last was a delightful surprise and brought me from feeling 69 to feeling 13! Yeah – part of me wishes this is what my 13th birthday would have been like, but I’m dreaming. Oh my childhood was wonderful, but on a minister’s pay my parents could not afford something like the Unitron 114 then, nor would I have appreciated it, much less what it could show me.  No – it’s taken all of the intervening  years for my deep appreciation of the night sky to evolve to where it is now – and with that, my appreciation, for the pristine views provided by small, long focal length refractors.

I didn’t dwell on M31 & company, however. I sucked in a deep breath, took a great picture in my mind which I can still see now, and swept up Almach, a very easy task since it is almost exactly second magnitude and lies at the end of the line of stars that slide roughly down a slope from a corner of the Great Square of Pegasus to the Demon Star, Algol. The 32mm yields 28X and a field approaching 2 degrees, so most of the time I use it as my finder. Sitting behind a long, thin scope makes it pretty easy to point with reasonable accuracy anyways. This is one way, however, that Almach differs from Albireo. In fact, if I were helping someone get started in observing double stars, I’d start them with Almach, assuming it was the right time of year. Finding Albireo isn’t that easy. It’s a full magnitude fainter, so it doesn’t leap out to the naked eye. And when you turn a scope or finder in its direction you’re going to see a much richer – and much more confusing – star background because Albireo is right in the Middle of the Milky Way.

What struck me first about Almach this morning, however, was the intensity  – no, that’s not quite right – the hue is the correct word. It had that rich yellow-going-to-brown look that defines the color gold. Maybe a hint of brass, even, but in the end gold – true gold. In the 32mm its companion was hinted at. Were the seeing better – it was average – I’m pretty sure I could have picked out the secondary, but it was much easier to do with a 21mm Plossl at 43X. And the view got better as I marched on up to 69X and then 86X. It was there I stopped. That was perfect: Gold and blue with just the right amount of clear black sky between them. This last is a judgment, of course –  find out what works best for you. This suited my taste perfectly this morning – and I did my best to imprint the impression, before turning 180 degrees and sweeping through the Milky Way for Albireo. Here I returned to the 32mm and here, of course, is the most obvious difference with Albireo.

At 28X it is a very easy split – in fact half that should do fine, for Albireo’s components are 33 seconds of arc apart, more than three times that of Almach’s!

So the experience of the two is quite different, though the similarity in color is striking. They are also similar in that they both consist of a primary that is expanding in its old age – the first stages of dying. And secondarys that are relatively young and hot. But where there is nearly three magnitudes difference between the primary and secondary of  Almach, there is just a bit more than a magnitude difference between the two stars of Albireo. And while there is no question that the two stars of Almach are gravitationally linked, there is serious doubt when it comes to Albireo. They may be – they may not be – but if they are, they are quite distance and take an awfully long time to complete an orbit.

James Kaler does a great job describing both stars from a more scientific perspective. Here are some highlights from his site. After noting the sky abounds in doubles, he says:

Among the best of all, however, is the last star of the string of bright beauties that helps make the constellation Andromeda, second magnitude (2.16) Almach, Andromeda’s Gamma star. . . Through the telescope the star is extraordinarily lovely, even a small instrument showing a superb pair separated by a good 10 seconds of arc, the brighter one golden yellow the other blue.

While pointing out that the primary is bloated to the point that it would fill our solar system out to the orbit of Venus, he notes:

More remarkable, the fainter blue-green component, Gamma-2, is ALSO double, though the duplicity is far more difficult to see. Fifth (5.1) and sixth (6.3) magnitude white hydrogen-fusing dwarfs . . . orbit each other with a period of 63.7 years separated on average by but 0.3 seconds of arc . . . . Yet again the system splits, as the brighter of these two is ALSO double, though detectable only with the spectrograph . . . The naked-eye star we know as Almach is thus quadruple, making it a feast for both the mind and for the eye.

Kaler goes wild about Albireo as well. In fact, he includes it in his wonderful book, “The 100 Greatest Stars.” On the web site, among other thngs, he notes:

Albireo is actually triple. The brighter yellow-colored member, Albireo A, is a much closer double made of a third magnitude (3.3) class K (K3) stable helium-fusing bright giant and a hotter but dimmer (magnitude 5.5) class B (B9) hydrogen-fusing dwarf, the two stars not readily separable in the telescope. The K giant has a temperature of around 4400 Kelvin, a luminosity 950 times that of the Sun, a radius 50 times solar, and a hefty mass of about 5 solar, while the close companion comes in at 11,000 Kelvin, 100 solar luminosities, and 3.2 solar masses. On average separated by about 40 Astronomical Units.

You can get a good look at Albireo from June to December.  Almach is in prime time in the Fall. To duplicate what I did this morning – see them both while  high in the sky – you don’t have to get up at 3 am. From mid-October to mid-December Almach is well up in the east a couple hours after sunset, while at the same time Albireo is still high in the west.

In the gathering predawn light I ended a beautiful morning observing session by slowly increasing the magnification on Jupiter.  I stopped at 86X. I’m not much of a planetary observer, but I could swear I could detect the ghost of the South Equatorial Belt which went missing a couple of months ago when Jupiter was behind the Sun. Wonder if it’s coming back now? Sure looked like it to me.