• 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.

Cavorting with Caph: Part 2 – Bu 253, Bu 485, Σ 3057, Σ 3062, and STI 1287

On this circuit around the southeast and southwest side of Caph, we’re going to take a look at a much brighter and much more distinctive group of stars.  And if you happened to land here without reading the first part, it can be found right here, which is a better place to start than where you are now!

Before we begin again, let’s put the finder chart at the top of the page where it’s within easy referential reach:

Line yourself up on Caph’s dusky yellow-gold glow, strap yourself into your observing chair, and we’ll wander off for a look at about as diverse a bunch of stars as you can imagine. (Stellarium screen image with labels added, click on the chart for larger view).

With Caph centered in your finder, take a peek about half a degree (30′) to its southeast and you’ll see two tight groupings of stars.  The first one is Bu 485/ARY 8, and the second one is Bu 253/ARY 7.  Slide on over to the first group and let’s take a look in the eyepiece at three of the finest class B stars in this sector of the galaxy.

Bu 485/ARY 8       HIP: 876   SAO: 21171
RA: 00h 10.8m   Dec: +58° 46′
*****               Magnitudes       Separation       Position Angle        WDS
ARY 8             AB: 8.1, 8.6             39.00″                  100°                  2011
ARY 8             AC: 8.1, 8.3          104.70″                    43°                   2011
Bu 485     Ca,Cb: 8.8, 9.5               0.10″                 257°                   1994
Distance:  1900 Light Years
Stellar Classification    A: B7      B: B6      C: B3

STI 1287   (No HIP or SAO number)
RA: 00h 10.1m  +58° 47′
Magnitudes: 9.6, 12.1
Separation:  14.4″
Position Angle: 310°  (WDS 2008)
Distance: ?????
Stellar Classification: A0
Discovered in 1910 by Father John W. Stein

When I first spied what turned out to be Bu 485/ARY 8 in my finder, I was immediately intrigued by its tight little open cluster appearance.  Centering it quickly under the barely illuminated red cross hairs, I eagerly bent down to the eyepiece — and wasn’t one bit disappointed.  Let’s take a look at two views of it.

First,  a black and white shot:

Bu 485/ARY 8 is composed of the three stars sitting at the center of this view. (STScI photo, east and west reversed, click for a larger view).

. . . . . and now a color shot, which is very Pleiades-like:

Aladin photo, east and west reversed once again, click to enlarge the view.

. . . . . and last, a sketch of the area, with Bu 485/ARY 8 offset to the north in order to squeeze Bu 283/ARY 7 into the south edge of the field.

There are three easily split multiple stars visible in this sketch, a non-double close pair at the extreme north edge, and an un-splittable pair parked in the west quadrant. (East & west reversed to match the refractor view, click on the sketch for a much better view).

I didn’t see the nebulosity surrounding the three stars of Bu 485/ARY 8 on my first view because of poor transparency, but I was back on another night when it was very obvious in my six inch Celestron f/8 refractor using both a 20mm TV Plössl (60x) and an 18mm Radian (67x) — all three of its eighth magnitude blue-white stars were solidly enmeshed in it.  From there the wispy nebula circled its way up to STI 1287,  then wound around to the very close but unrelated pair of stars above the “C” component of Bu 485/ARY 8, and finally returned home once more, entering the back door at “C”.  It really was a pleasant and unexpected sight.

STI 1287 proved to be an easy split in a four inch refractor, throwing up its double-starred hands and surrendering quickly to a TV 102 and an 18mm Radian, at a very moderate 49x.  Even that close pair above the “C” component of Bu 485/ARY 8 was visible at that magnification.  And of course, all three of the latter’s stars were easily seen — in fact, they’re more than willing to cooperate with a 60mm refractor.

Now that nebulosity-circled triple star which is the center of our attention carries two designations, and even though I listed Bu 485 first, it’s really ARY 8 that we’re looking at.  “Bu” is a designation that catches the eye of an experienced Star Splitter, whereas ARY almost looks like it could be a misspelling of airy disk.  It isn’t, though — ARY actually refers to R.W.Argyle, an astronomer based at Cambridge University in England. I believe he is the same Argyle who edited Observing and Measuring Visual Double Stars, which happens to be a rather handy book to have around a telescope.  However, the Washington Double Star Catalog (WDS) lists the first date of observation of the three stars of ARY 8 as 1910, and all of Argyle’s observations are more recent than that, so I’m not sure why or when the ARY designation was attached to these stars.

It may be that eagle-eyed S.W. Burnham contributed an observation of those three stars in 1910, but there is no doubt he was looking at them when he first spied the two-sided aspect of the “C” component in 1874.  His first glimpse was with the 9.4 inch refractor housed at the Dartmouth College Observatory, and he confirmed it four years later with the 18.5 inch Clark refractor at the Dearborn Observatory at Chicago.  He measured the separation of Ca, Cb at 0.41″ in 1878, 0.44″ in 1889, and 0.43″ in 1891 — so it appears the two stars have closed considerably since that time, and are well beyond the reach of 99.99% of us.

Just for the record, the statistics on the un-splittable HDS 20 shining in the western quadrant are magnitudes of 8.5 and 9.9, separated by 0.3″ at a PA of 164 degrees, discovered in 1991 by the Hipparcos satellite (HDS refers to Hipparcos).

Bu 253/ARY 7        HIP: 848   SAO: 21161
RA: 00h 10.4m  +58° 31′
*****                 Magnitudes       Separation       Position Angle        WDS
ARY 7               AB: 7.8, 8.3          124.40″                     3°                    2011
Bu 253      Ba, Bb: 8.9, 9.0               0.40″                   32°                   2008
Distance: 253 Light Years
Stellar Classification    A: A5    B: A

And over in the south corner of the sketch above is the spectacularly wide and visually unspectacular Bu 253/ARY 7, which is about as unlikely a paring as I can imagine.  While ARY 7, the wide pair, actually does rather well in a small aperture scope, Bu 253 (the Ba, Bb pairing) is about as distantly placed on the opposite side of the visual scale as infrared is from ultra-violet on the electromagnetic scale.  This is the pair Burnham was looking at in 1874 with the 9.4 refractor at Dartmouth when he first detected the dual nature of the Ca, Cb pair described above.  As for the Ba, Bb pair of Bu 253, Burnham measured the separation at 0.65″ in 1889 and 0.60″ in 1891.  The pair was actually first measured by the industrious Baron Dembowski in 1875, at a separation of 0.42″.  (Burnham’s measurements for Bu 253 and 485 can be found on page two of this book).

Now, with Bu 253 centered in your finder, move west a mere 30′ to our next pair of stars, which should easily be seen in your finder.  For reference, here’s another look at the chart at the top of the page.

Σ 3057  (H I 39)       HIP: 398   SAO: 21062
RA: 00h 04.9m   Dec: +58° 32′
Magnitudes:  6.7, 9.3
Separation:   3.8″
Position Angle: 298°  (WDS 2009)
Distance: 2700 Light Years
Spectral Classification: B1, B6

Σ 3062                   HIP: 518   SAO: 21085
RA: 00h 06.3m   Dec: +58° 26′
Magnitudes: 6.4, 7.3
Separation:  1.55″
Position Angle: 350.5°  (WDS 2012)
Distance: 66 Light Years
Spectral Classification: G5, G8
Status: Gravitationally attached, orbit can be seen here.

You might call these the Double-Double of Cassiopeia, although I suspect there are at least a few other candidates for that description lurking in the constellation’s confines.  They’re certainly more difficult to separate than the more well known Epsilon Lyrae, but with their wider ranges of magnitude difference they also offer a very different aesthetic perspective to the experienced eye.

I actually had this pair on a long list of stars I was planning to look at in Cassiopeia last fall when I found myself wrapped in the charms of Sigma (σ) Cassiopeiae, but rain-clouds-wind-horrible-seeing-etc put those plans on hold.  Neil English, that dedicated explorer of dual points of light in Scottish skies, returned my attention to them several months ago after cornering them in his five inch Russian Tal refractor, the attractive Tanya.  So in the wee hours of an early September morning, under blessedly stable skies, I pointed my six inch f/10 refractor way up into the northern heavens, and found this:

Picture perfect! Each star rests calmly and distinctly at opposite corners of the field of view, with very few stars competing for visual attention. (East & west reversed to match the refractor view, click on the sketch for a more vivacious version).

I don’t know which member of this pair I prefer more — it’s a tough choice to make, because both have an allure all their own.

In willing compliance with their class B spectral specifications, the Σ 3057 pair is most definitely blue, but under less ideal seeing conditions, I’ve seen hints of yellow in the 6.7 magnitude primary.  This pair can be a bit tougher to pry apart than its counterpart because of the 2.6 magnitudes of difference between the two stars, but you’re likely to find your heart has been captured when you finally see that first spark of white light struggling to escape from the 9.3 magnitude secondary.  It’s another one of those pairs of disparate magnitude stars that are spaced just closely enough together to challenge your visual acuity.  On nights of poor seeing and/or transparency you’ll find them a struggle to separate, while on more atmospherically cooperative nights, both stars will be waiting calmly for you to feast your star-starved observing eye on them.

In contrast, Σ 3062 is distinctively tinted with very yellow photons, although it has a pronounced tendency to lean to the orange side of the color bar on many a night.  With only nine-tenths of a magnitude of difference between its two class G stars, and much more tightly spaced than its stellar mate at the opposite edge of the field, it is an absolutely beautiful sight the first time you see it transform itself from an elongated star into two distinct dots of shimmering yellow-orange light.   The view of it which is still etched deeply in my starry memory came on September 17th of this year, when I found myself admiring a tear inducing split in my 127mm f/9.3  Meade AR-5.  In the lens of a 6mm Astro-Tech Plössl (197x), Σ 3062 appeared as an apparition of two exquisite orbs of orange-gold light with a well defined black slice of intervening interstellar space wedged firmly between them.  Stunning and delectable.

Both Σ 3057 and Σ 3062 should be within the reach of a good four inch refractor, although I haven’t yet tried it, but — hold it — hang on there a moment — new data just now coming in! . . . . . . . . . . .

. . . . . . . . . . . The night of the afternoon I wrote the previous paragraphs, I decided to give my too-long-ignored Tasco 76mm f/15.8 refractor a spin around the sky.  The moon was about 98% full (it was actually waning, believe it or not), so I thought I would look at a few old favorites for a while with it — and that long white tube looked absolutely ravishing in the moonlight.  Eventually I spied Caph coming over the pine trees in the northeast, so I swung the scope up there, admired Caph’s luscious golden glow, took in Bu 485/ARY 8, and then decided to see what would happen with the Σ 3057 – Σ 3062 pair.  I thought I was looking at a very faint glimmer of light right where Σ 3057’s 9.3 magnitude secondary should be, but considering the low magnification (60x) of the 20mm black & orange Celestron Plössl I was using, I really wasn’t buying it.  The air was very dry for a change, but the seeing was being bounced back and forth between a II and a I by the strong wind responsible for the dry air.  I inched up to a 17mm version (71x) of the same eyepiece — that faint glimmer was still glimmering, and I still wasn’t buying.  But not seeing any reason to stop there, I reached for the next Celestron member of that eyepiece line, a 12.5mm Plössl (96x), took another look, and now I knew I had it!!!  It was really really there!!!  A mere wee bit of white light, but a very steady and definite wee bit of white light it was!

I tried to wedge a thin line of empty space between both members of Σ 3062, going as high as 160x with my trusty old 7.5mm orange and black Celestron Plössl, but the seeing was just too shaky to allow it — and I really wasn’t expecting it anyway.  No matter — I was still dazed by my success with Σ 3057.  I have to give most of the credit to the dry air — if the usual amount of coastal moisture had been in the air, the glow surrounding the primary would have performed at its usual blotting-out-best.  But that old Royal Optics lens in the 76mm Tasco really deserved the pat on the dew shield I gave it  — gotta get that thing outside more often!

As I’ve said before . . . . . . . . . you just never really know until you really really try.

There’s one more part to this circular Caph-ian circuit, and it’s already brewing and percolating in a burgeoning computer file.  Grab an empty cup and be prepared to fill it with a few views that have no match!

Proceed to part three  ➡  here!


One Response

  1. John,
    I was able to split Struve 3057 last night. We had a Star Party for some U of H people touring the summit. The WX was a bit tough with high cirrus clouds out of the south and seeing was intermittent. We couldn’t split Struve 3062 though. With my Explore Scientific 2″ 18mm and my C925 we could easily see dark between the yellowish primary and the bluish companion of Struve 3057. I was hoping to get some others from this post, and it got a bit cold. We did get a few from Sissy Haas’ list. Tired from show & tell, we packed up a bit after midnight as the wind increased.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: