• 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.
  • Advertisements

And Yet Another Triangular Traipse: 15 Trianguli, Σ 285, and Σ 286

We’re back in Triangulum once again, hemmed into this rather small three-sided constellation in search of interesting double stars — and this time we’re going to wander into its southeast edge, near the border with Perseus and Aries.

I’ve pried loose two of the most un-alike pairs of double stars you can imagine – one is 60mm material (actually, a 50mm lens will do just fine), and the other is a very comfortable fit for a 100mm scope —–although if you hold you mouth just right and promise not to utter mutter-ous phrases, you might be able to get it with a good 90mm lens.  And while I was roaming around up here, I  just happened to bump into that last double’s distant sibling, which wasn’t quite as willing to surrender to my telescope as easily as its older brother.

First, the navigational chores – and pay attention, because it isn’t hard to make a wrong turn and end up in Perseus without permission.

First, an overview of where we are can be seen here.

Next, a close-up view of Triangulum’s southeast corner, with our two targets identified:

You’ll find 15 Trianguli three degrees to the east of Gamma (γ) Trianguli, Σ 286 is one degree southeast of that, and Σ 285 is just a short half degree south and very slightly west from there.  (Stellarium screen image with labels added, click for a larger view).

Then we’ll get a bit closer:

(Stellarium screen image with labels added, click once more for a larger view).

And now we’ll warm up our observing eye on the widest pair of the bunch:

15 Trianguli  (AG 304)         HIP: 12086   SAO: 55687
RA: 02h 35.8m   Dec: +34° 41’
Magnitudes: 5.57, 6.75
Separation:  142.2”
Position Angle: 16°  (WDS 2003)
Distance: 630 Light Years
Spectral Classification: M3, A5

125mm, 50x: A very wide pair with superb colors.  It’s a bright pumpkin-orange star and a bright pearly white.  They look like a pair, though a very wide one.                          (From Double Stars for Small Telescopes, Haas)

Hmmmm . . . . . . . . . . . . Not quite what I saw in the secondary, anyway:

More like orange (you pick a shade, I’m not fond of pumpkin) and BLUE with a touch of white. Distinctively blue – even in a 60mm refractor. Star colors – sublimely unpredictable things they are. (East & west reversed in the sketch to match the refractor view, click for a larger version).

My first look at this wide pair of stars was in my Skylight 100mm f/13 refractor, which enhanced the colors even more than what you see in the sketch, thanks to the additional forty millimeters of aperture.   But captured by color as I was, I decided to sneak a peek in the 60mm f/15 refractor I have mounted atop the Skylight —  and I found the color was still pretty spectacular.

So I proceeded to put it on paper.

The 60mm f/15 is shown here when it was roosting atop a Celestron f/10 100mm refractor — click to get a larger view.

There’s just something about the view in a good 60mm scope that grabs me every time.   As long as I’m working with magnitudes that are within easy reach of the lens, the visual appearance of the stars always strikes me as quite crisp and precise, kind of like a tender steak cooked to perfection – and I really couldn’t resist the aroma of this one.  Probably it’s an acquired taste –- if it is, it’s certainly worth acquiring.

I’m not sure what the story is regarding the history of this pair of stars.  They’re so wide that apparently Herschel and the nineteenth century double star sleuths overlooked them.  The first recorded observation, which resulted in the AG 304 identifier now attached to 15 Trianguli in the Washington Double Star Catalog (WDS), was in 1896, and is credited to the Astronomische Gesellschaft, Leipzig.   This particular organization (the German phrase means astronomical association or society)  is the second oldest in existence, having been founded in Heidelberg in 1863, with various branches around Germany, and is still in existence today.  Their web site can be found here.

Now that our observing eye is well-tuned to stellar wavelengths, we’ll wander to the southeast with a slight turn to true south, as shown on the last chart above —- or for convenience, you can get to it from here as well.

Σ 285  (Listed in error in the WDS as H I 21)          HIP: 12328   SAO: 55748
RA: 02h 38.8m   Dec: +33° 25’
Magnitudes: 7.48, 8.14
Separation:  1.7”
Position Angle: 162°  (WDS 2008)
Distance: 700 Light Years
Spectral Classification: K2

And as you can see in the data line above, the William Herschel catalog number listed in the WDS Notes file for Σ 285 is in error – which is a long, long, looooooonnng story.  I’ll have to save that for the next post — for now, let’s just wander over to the eyepiece and have a look:

Look to the lonely left to spy the tight orange-tinted pair belonging to Σ 285. (East & west reversed, click on the image for a larger view).

Click on this STScI image to get a larger view showing eight separate galaxies.

This is really a rather unique eyepiece view.  On the one hand, there is an absolute lack of background stars in about eighty-five percent of the field, while on the other your eyes are drawn immediately to the zig and zag of stars lined up along the north side of the view.  If you were to go a whole lot deeper with a much larger telescope you would discover quite a few background galaxies, including a 15th magnitude spiral just a few minutes northwest of Σ 285.

There could even be evidence of ordered intelligence here, too – but I suspect it’s really just random luck.  I’m referring to the ascending brightness of the labeled stars along the north edge of the field as you move from west to east: SAO 55754 is a 9.2 magnitude K2 class star, SAO 55758 is an 8.7 magnitude F0 star, and SAO 55760 is a 7.9 magnitude class K0 stellar furnace.  On a reasonably transparent night, their orange-red and yellow-white rays add a definite touch of class to a subdued stellar scene which is quite stunning on first sight.

And if you look closely, just a few arc minutes to the south and slightly east of Σ 285 you’ll find two very faint points of light, about 11th magnitude, that look suspiciously like a related pair of stars.  I was fooled at first into thinking they were SEI 25, magnitudes of 11.2 and 12.2, separated by 24.1” at a PA of 268 degrees (WDS 1997).  The position angle is almost an exact match, and the magnitudes are very close,  but the separation is actually a bit wide – purely a convenient case of mistaken identity and a good example of how you can easily be misled if you’re not careful.  I searched my sources for whatever morsel of information I could find on this dim pair, but was unable to unearth any indication that they’re more than a whimsically random affair.

As it turns out, the genuine SEI 25 pair is actually 35 arc minutes further south, a fact I didn’t discover until almost two weeks after the sketch above was done.  So I set off in search of them one murky mid-November evening and found the seeing so abysmally poor I couldn’t detect them at all in the shimmering celestial soup.

As for the main attraction, Σ 285, I was surprised at how distinctively separate its two closely matched stars were in the 100mm f/13 lens.  They’re barely touching each other in the sketch, but it was easy enough to get a clean break between them at 144x with a 9mm UO Ortho.  I returned in early October with my six inch Celestron f/8 refractor and was rewarded with a stunning view of this salmon orange pair in a 6mm Astro-Tech Plössl (200x) — highly recommend on a crisp fall evening with a warm cup of tea nearby.

Σ 286               HIP: 12417   SAO: 55761
RA: 02h 39.9m   Dec: +33° 57’
Magnitudes: 7.8, 10.2
Separation:  2.9”
Position Angle: 258°  (WDS 2010)
Distance:  1400 Light Years
Spectral Class: K0

So now we drift a short 35 minutes north and find ourselves trying to find Σ 285’s rather remote sibling (700 light years vs. 1400 light years), Σ 286.  I found this pair on the same night I failed with SEI 25, but only after an intensive search, thanks to the atmosphere of non-cooperation.  On a night of good seeing, this one should be a breeze in a six inch refractor – but on a night of poor seeing, it’s a real stellar struggle.

Perseverance is pretty much the only way sometimes, so eventually I got this far:

Neat, compact, with a noticeable void in the southwest corner of the field. (East & west reversed, click on the sketch to see that secondary just a bit better!)

What we have here is a study in contrasting separations and magnitude.  Even though the Σ 285 pair is considerably tighter at 1.7”, the magnitudes are similar enough that they don’t contribute to the difficulty of seeing both components.  But then when we turn to Σ 286, the 2.4 magnitudes of difference seem to have made a devilish pact with the 2.9 arc seconds of separation, dragging us against our will into a bit of a battle when the seeing isn’t cooperating.

On my first approach with a 14mm Radian (109x), I thought I could see a faintly fragmented wisp of flickering secondarial light —- so I switched to a 12mm Radian (127x), crept up on it cautiously, and eventually managed to catch it clearly in very brief moments of slightly better seeing.  I went as high as a 6mm Radian that evening, but 253x was about 126 more x’s than conditions would condone, so I settled in with the twelve millimeter’s 127 x’s.

Now — that takes us back to Σ 285 and the mistaken H I 21 connection — which has more twists and turns than a worn out slinky on an out-of-control merry-go round.  You’ll have to stand by for that one, which will surface shortly in the next post.

Until then, hope your skies are doing better than mine!  🙄


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 )

Google+ photo

You are commenting using your Google+ 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 )


Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.

%d bloggers like this: