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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!   😎

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One Response

  1. wonderful report john!! And the sketch’s really look nice.
    mike hyrczyk

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