• 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.

Porrima’s Pals: Σ1677, S 639, Σ1690, and Σ1719

Now, let’s face it.  We can’t all be bright and famous like Porrima.  Most of us (probably not me, though 😉 ) have to be average in order for things to average out.  And there’s nothing wrong with being average.  You can even be average and still stand out from the crowd — just don’t get too carried away and get arrested.

So what in the name of Virgo is he talking about now? — you ask.

Well   …..   I’m referring to the dimmer doubles — and the ones with less than spectacular separations — and those with position angles that aren’t pretty.  In other words, the average ones.  The ones that don’t make your focuser knob spin all by itself.

You know, you really can come to love those things.  Honest.  But it does take time.  It’s kind of like an ugly dog that wanders up and won’t leave  …..  and after a week or two, you find you’ve become attached to the poor mutt and don’t want it to leave.

A lot of double stars are kind of like that.

For instance, consider Theta (θ) Virginis, a triple star I’ve written about elsewhere.  Now the first time I looked at it, I was totally unimpressed and completely underwhelmed.  It wasn’t ugly, it was just  ……  there.  It was average.  But I went back and took another look a few months later, and then went back again another month later — and before I knew it  …….  I found I actually enjoyed  looking at it.  I would challenge myself with it in a 60mm scope;  I would look at it with larger apertures and enjoy the spectacle of the close secondary hugging the primary while the third component drifted all by itself in the distance;  and I would turn up the magnification on it in my six inch refractor high enough to drive all three stars so far apart they would take up most of the eyepiece, and rejoice in the space I had seemingly created.

And that’s the point of this stellar ramble.  The finer things in life — and in the sky — take some time to sink in.  Refinement doesn’t come from having your rods and cones blasted with two yellow-white third magnitude stars that are barely separated at 200x — although without a doubt that’s a spectacular sight — and I’m definitely addicted to it.

BUT — appreciation of the more subtle aspects of stellar beauty simply takes some time — and patience — in order to work its magic.  Just as absence makes the heart grow fonder  — at least most of the time — dimmer doubles demand more attention.  And then all of sudden that memorable night comes along  when you find their familiar sight is rather  ……..  well, let’s call it comforting.

So, let’s pick a few of the lesser stellar spectacles near Porrima and become  ……..  familiar.

And remember, these are Porrima’s Pals, too, and you can’t do much better than that!

Our four average targets hover here south and east of the Retreat of the Howling Dog. (Stellarium screen image with labels added, click on the chart for a larger view)

We’re going to look at three doubles and one triple that spend their nights hovering to the south and east of Porrima.  The chart above gives you a good idea of how they’re situated in relation to the rectangle that is formed by Spica, Zeta (ζ), Delta (δ), and Porrima.  To digress for a moment  —  just a short one, I promise  —  there’s another asterism of sorts lurking on that chart.  It’s formed by Epsilon (ε) — which is out of sight above Delta at the top of the chart — Delta (δ), Porrima, Eta (η), and Beta (β).  Known as the Retreat of the Howling Dog, it’s associated with the Arabic name for Porrima, Zawiat al Awwa, which means The Angle (or the corner) of the Barker.  Think of it as a possible home for that poor average mutt that wanders up and needs a place to stay.

But now, let’s turn up the magnification a bit, and go to the chart that we’ll use for this tour:

A Closer Look: Three of the Porrimian Pals are seen here loitering to the southeast of Porrima — Σ 1677, S 639, Σ 1690 — while Σ 1719 hovers above them all at the northeast corner of the chart. (Stellarium screen image with labels added — click to enlarge)

Σ 1677  (H III 53)             HIP: 62234    SAO: 138952
RA: 12h 45.3m   Dec: -03° 53′
Magnitudes: 7.3, 8.1
Separation: 16.1″
Position Angle: 348°    (WDS 2005)
Distance: 1084 Light Years
Spectral Class: A9

First on our list, and the closest of Porrima’s Pals, is Σ 1677, which is just a skip and two hops from Porrima.  To get there, skip about a third of a degree to the east and slightly south from Porrima to 5.9 magnitude HIP 62103, which is very obvious in the eyepiece of your finder when Porrima is centered.  Then turn to the south and you should see two stars that form a straight line.  Hop to the first one, 6.8 magnitude HIP 62141, and hop the same distance once more to land Σ 1677 in your eyepiece.

Σ 1677 standing out in its field. East and west are reversed to match the refractor view, click for a larger image.

This one stands out rather well from the other stars in the field  —  you might describe it as above average for its surroundings.  For once, I could see more color here than Haas, which is the first time I can remember that happening.  In my 105mm refractor, the primary was white and the secondary was what I would call “yellowish” — Haas calls it  gray.

She was looking at it with a 60mm scope at 25x, which may have something to do with that.  I found the secondary easy to see in my 60mm f/16.7 at 50x, but didn’t make a note of the color at the time, so I’ll have to go back and check again when they skies cooperate.  At any rate, this one deserves a place on anyone’s list of doubles easily seen in a 60mm refractor.

S 639  (H V 129 — AB only)      HIP: 61685    SAO: 138885
RA: 12h 38.7m   Dec: -04° 22′
Magnitudes: 6.8, 10.0, 10.2
Separation:  AB  56.0″   AC 164.6″
Position Angle:  AB 110°  (WDS 2002)     AC 359°  (WDS 1999)
Distance: 764 Light Years
Spectral Class: M0

Now, if you take a peek in your finder while Σ 1677 is still centered in the eyepiece of your scope, you’ll see 7.8 magnitude HIP 62039 a bit more than half a degree to the southwest.  Extend that line another half a degree southwest and you’ll find our next target, a relatively wide triple that carries Sir James South’s designation, S 639.

S 639 with horizontal accompaniment. East and west reversed again, click to enlarge.

What struck me immediately when I looked at this was the unusual arrangement of stars in the field of view.  If you look at the sketch to the right, to the west of S 639 you’ll see two horizontal stars of about 10.5 magnitude aligned along the same axis as S 639’s primary and secondary, along with another star of similar magnitude on the opposite side which is on the same plane as the western pair.  And to the north, you’ll see the 10.2 magnitude “C” component floating up there all by itself.

Same group of stars, but rotated about ten degrees to the north. (STScI photo, click to enlarge)

I’ve also included the STScI photo, which shows the alignments tilted about ten degrees to the north — just enough to lose the effect shown in the sketch.  Of course, it’s still there, but because you have to look for it, it doesn’t quite strike you in the same way.  So it seems I caught these stars at a time when their alignment was unique enough to make them distinctive, as opposed to average — rather a stellar example of how the mind perceives patterns.

In the 105mm refractor, I would describe the primary as yellow-white.  I needed a five inch refractor to detect a bluish-white tint to the secondary, and “C” I’ll just call pale white.  Haas quotes Phillips as having seen a vivid yellow and blue in a 225mm scope — and I’m sure that the extra aperture warrants the adjective “vivid.”  Admiral Smyth, on the other hand, saw pale yellow and “greenish.”

In my 60mm f/16.7refractor, which sits on top of the 105mm refractor, at 50x I could see a perfect miniature of the view in the larger refractor — I didn’t expect to see it quite that way, so it was a pleasant surprise.

Second chart once again just to make things easier! Click to enlarge.

Σ 1690  (H II 42)          HIP: 63139    SAO: 139049
RA: 12h 56.3m   Dec: -04° 52′
Magnitudes: 7.2, 9.0
Separation: 5.9″
Position Angle: 149°   (WDS 2005)
Distance: 556 Light Years
Spectral Class: A0

If you look at the chart above, you’ll see that S 639 and Σ 1677 form a line that extends to the northeast just past sixth magnitude 38 Virginis.  Σ 1690 lies southeast of 38 Virginis (about the same amount of distance that separates 38 Virginis from Σ 1677), so a short hop to 6.5 magnitude HIP 62915 followed by another short one to 7.3 magnitude HIP 63070 will lead you right to it.

This one is much tighter … so you’ll have to look a bit closer. East & west reversed, click to enlarge!

This one is much tighter than our first two stars, so you’ll have to look just a little bit closer to detect the 9.0 magnitude secondary.  I had no problem picking it out with the 105mm refractor and a 16mm eyepiece (94x), but in the 60mm f/16.7 refractor, there was only a mere hint of a split at 50x, mainly because there was just enough haze in the sky to make it difficult. Haas, though, coaxed a more memorable view from her 60mm scope:

60mm, 45x: Striking contrast for the separation!  An ash-white star almost touching a tiny nebulous dot, and the little companion can be seen only with averted vision.

I’ll have to come back to this one on a better night with a 60mm scope and give it another try — judging by her description, I might even get hooked on this one, too!

In the 105mm refractor, I was able to see the same white Haas described, and on a later night with a five inch Meade (AR-5), I thought I detected a bit of a reddish-orange tint in the secondary.  I need to double-check that on a better night, also, since I didn’t expect to see color in a ninth magnitude star.  If you can confirm it — or see another color — tell us about it in a comment to this post.

Σ 1719            HIP: 64030    SAO: 119774
RA:13h 07.3m   Dec: +00° 35′
Magnitudes: 7.6, 8.2
Separation: 6.9″
Position Angle: 359°   (WDS 2009)
Distance: 246 Light Years
Spectral Class: F5, F9

Our last star will require a bit more star-hopping skill than the others, so be prepared to work just a bit for this one.

If you look again at the last chart, you’ll see that it’s due northeast of Porrima, but at about six and half degrees away it’s just a bit more than the five degrees between Porrima and our last star, Σ 1690.  We’ll start at Porrima, but I’ll excuse you while you spend some time cranking up the magnification to pry those beautiful glowing yellow globes apart.  Just let me know when you’re ready to go.


Now?  OK, strap yourself in then, but you might want to give your eyes a few minutes to recover from that dual blast of third magnitude photons — we’re headed into some dim territory.

Let’s drop down to HIP 62103 again, just southeast of Porrima, and then draw a line three degrees east and slightly north to OΣ 256 — this one is a 7.3 magnitude double with components of magnitudes 7.2 and 7.6, separated by a mere nine-tenths of a second of arc.  We’ll pass on that one for now, on the presumption that we’ll need at least six inches of aperture to get it, which is more than we have out on the observing deck tonight.  While you’re on the way to OΣ 256, you might also get a glimpse of NGC 4753, a tenth magnitude galaxy with a low surface brightness of 12.2 — meaning it’s a bit more difficult to detect than that tenth magnitude would lead you to believe — and I didn’t see it on this particular night.

From OΣ 256, we’ll move two degrees further east with a slight nudge to the north to reach another 7.2 magnitude star, HIP 63083.  Then we’ll turn due north and move about one degree to 6.8 magnitude HIP 63810, bend to the northeast and move one more degree, and we’re there!  Whew, a long sojourn through a barren field!

. . . two white stars of about the same brightness. East and west reversed once again to match the refractor view. Click … to … enlarge!

And you should find yourself looking at two white stars of about the same brightness.  This is actually a rather attractive pair of stars, and it dominates the field of view.  By the time I got to it, the seeing was deteriorating, but I was still able to split them — barely — with the 60mm f/16.7 at 50x.  I came back later with the AR-5 to see if I could detect any color, but I saw the same white-white of the previous observation.  So, we’ll call them both white.

Haas quotes Phillips, who used a 225mm scope on them — “… both stars white. An excellent object.” — and Harshaw, with a 200mm scope — “Very fine object.  White, lilac.”

LILAC???  I don’t know what to make of that in this case, considering Phillips stayed with white in a bit more aperture.  That, plus the fact that both stars have the same stellar classification, F.   But, when it comes to star colors,  there are so many variables at work on any given night that just about anything is possible.

I’m stayin’ with white, though.  After all, it’s an average color.

So now — pick one of the four stars we’ve just looked at — no, NOT Porrima! — and go back to it in a few weeks.  Linger over it for several minutes and allow the image of it to become etched into the photon enriched neurons of your memory circuits.  Go back again a few weeks later, and spend a bit more time with it at different magnifications and, if possible, with different apertures.  Then return a week or so later — and see if you don’t begin to find the familiar sight of it a bit “comforting.”

You gotta trust me on this — it works.  After a while, you’ll want to put a leash on it and take it home.

And now, considering it’s well past midnight and the dew is dripping from the bill of my Star Splitter’s hat, I think I’ll sneak inside and brew up an average cup of tea.

And then I’ll come back out and feast my eyes on Porrima’s dueling photons for a while — provided I can avoid the lure of Saturn.

Here’s to better than average skies!

One Response

  1. June 3rd, 11PM

    I took my own advice tonight and went back and looked at the four stars described in this post after not having peeked at them for almost a month.

    I was using two scopes — a 90mm f10 Orion achro and an 80mm f15 Mizar tube with a Carton lens. The seeing was horrible because of a steady 30mph wind, along with higher gusts, so it was a low magnification night.

    Of the four stars, I have to say that S 639 is my favorite. That asterism of stars that greets your eyes as you peer into the eyepiece after hopping to it with the finder really grabs your attention. It’s the way the stars are aligned on similar planes that I find so fascinating, more so than the double star itself. This one I might just put a leash on and keep around for a while. 😉

    The others were worth some time, too, especially the last one, Σ1719. In the 105mm refractor I viewed it in the first time, it’s an easy split. But it takes on more of a delicate quality at smaller apertures. I had to look closely in both the 80mm and the 90mm scopes to catch the secondary, and because I was staying with low magnifications in the range of 50x, they were much closer to each other than had been the case in the 105mm scope.

    I’ll be back on a better night, hopefully with a six inch refractor, and I’ll crank up the magnification and enjoy the different perspectives that result. Who knows, I may find I prefer one of the others instead. Part of the enjoyment here lies in how the appearance of these stars can change significantly at various apertures and magnifications.

    If you’ve looked at these and haven’t been back, time’s a-wastin! With the sun setting a bit later each night as the summer solstice approaches, this western half of Virgo is going to slip off into the horizonal haze in the southwest before too much longer — so get out there and take a look!

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: