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Wrestling on a Herculean Mat: A Tale of Two Close Encounters — OΣ 344 (with Σ 2290) and Zeta (ζ) Herculis

OK, it’s time to put away the low power eyepieces and aperture-challenged optical devices and get serious about prying into the diabolically difficult and totally torturous realm of high Delta doubles. Those would be doubles with magnitude differences of roughly two magnitudes or more. And to keep things manageable and sane, we’ll stay away from any pairs fainter than fifteenth magnitude. 😉

But in reality we don’t need to go anywhere near that faint – not that we ever could anyway – because the two stars we’re going to look at here are more than capable of making us yearn for less challenging targets such as Albireo or Mizar. In fact, keep a bottle of aspirin handy – you may need to subdue a headache caused by high-frequency stellar spinning-hopping-and-twitching.

We’re going to start way up high in the northeastern corner of Hercules with an enticingly innocent 6.47 magnitude star dubbed OΣ 344 by its discoverer, Otto Struve, and then re-dubbed STT 344 by the Washington Double Star Catalog (WDS).  If you didn’t know there was a tenth magnitude companion hovering near that 6.47 bundle of photons, you probably would skip right over it – which just goes to show there are times when ignorance can truly be bliss.

But since the fate of a double star addict is to be cursed with a surplus knowledge of numerical data, we’ve got no choice but to stop and take a peek.

Hang on tight.

Zeta (ζ) Herculis, the second star we’ll look at, is easily found at the southwest corner of the distinctive Hercules Keystone asterism. The star we’re in search of now, OΣ 344, is hiding two and a half degrees southeast of Gamma (γ) Draconis. Since it’s three and half magnitudes fainter than Zeta (ζ) Herculis, we’ll need another chart to locate it. (Stellarium screen image with labels added, click to enlarge).

Zeta (ζ) Herculis, the second star we’ll look at, is easily found at the southwest corner of the distinctive Hercules Keystone asterism. The star we’re in search of now, OΣ 344, is hiding two and a half degrees southeast of Gamma (γ) Draconis. Since it’s three and half magnitudes fainter than Zeta (ζ) Herculis, we’ll need another chart to locate it. (Stellarium screen image with labels added, click to enlarge).

We’ll start at second magnitude Gamma (γ) Draconis and move east and slightly south for a distance of 1° 45’, to 6.3 magnitude HIP 88732. Then we’ll cross the border into Hercules by making a half degree jump directly southeast to 7.3 magnitude HIP 88975 (also known as HU 674, a tight pair we’ll avoid since it’s separated by .52”).   Now hop just short of a degree (48’) southwest to our goal, 6.5 magnitude OΣ 344, which is at the north end of a faint, but distinctive, group of three seventh and eighth magnitudes stars. Be careful not to land on another similarly configured, but wider, group of four stars located another degree to the southwest.   I’ve labeled the northern member of that group, 6.2 magnitude HIP 88415 (also known as Σ 2277, which we’ll come back to in another post). (Stellarium screen image with labels added, click on the chart for a larger view).

We’ll start at second magnitude Gamma (γ) Draconis and move east and slightly south for a distance of 1° 45’, to 6.3 magnitude HIP 88732. Then we’ll cross the border into Hercules by making a half degree jump directly southeast to 7.3 magnitude HIP 88975 (also known as HU 674, a tight pair we’ll avoid since it’s separated by .52”). Now hop just short of a degree (48’) southwest to our goal, 6.5 magnitude OΣ 344, which is at the north end of a faint, but distinctive, group of three seventh and eighth magnitudes stars. Be careful not to land on another similarly configured, but wider, group of four stars located another degree to the southwest. I’ve labeled the northern member of that group, 6.2 magnitude HIP 88415 (also known as Σ 2277, which we’ll come back to in another post). (Stellarium screen image with labels added, click on the chart for a larger view).

OΣ 344 (STT 344)             HIP: 88754   SAO: 47233
RA: 18h 07.1m   Dec: +49° 43’
Magnitudes: 6.47, 10.31
Separation:  2.3”
Position Angle: 140° (WDS 2009)
Distance: 722 Light Years
Spectral Classification:  “A” is  A2

I was first made aware of the existence of OΣ 344 after wrestling two difficult high Delta pairs to a dubious draw in Ursa Major (namely Bu 1074 and Cou 1900) when Mark McPhee posted a comment about it – something like “If you’d like a taste of what Cou 1900 is supposed to offer, mosey over to STT 344 in Hercules – you won’t be disappointed.”  Now that’s like waving a dog-eared first edition copy of Burnham’s 1906 double star catalog in front of me, but I had to wait until seeing conditions aligned with the stars, so to speak.   It took most of a year, but I finally had my chance – and this is what things looked like on first approach:

As I said, very innocent looking – just another six-plus magnitude star beaming its white photons into a fairly sparse field. (East and west are reversed here to match the SCT view).

As I said, very innocent looking – just another six-plus magnitude star beaming its white photons into a fairly sparse field.  Note the location of ninth magnitude SAO 47230 — we’re going to need that later.  (East and west are reversed here to match the SCT view, click on the sketch to enlarge it).

So there I sat, parked permanently (at least it had begun to seem that way) in upper northeast Hercules, attempting to wrestle frantically wriggling white photons into a stationary image for long enough to visually grab that 10.31 magnitude secondary. Seeing conditions were OK – certainly not worth bowing to the sky gods for – but I had a hunch there was a chance.  The image in a 10mm Radian (245x) didn’t divulge anything, but since the frantic wriggle wasn’t high frequency yet, I reached for what is usually my ace-in-the-hole ocular, an old Celestron 7.5mm Plössl (327x) . . . . . and the wriggle not only advanced into high frequency territory, the image turned to mush. Suddenly I couldn’t buy a sharp focus with that eyepiece for all the Plössls on planet Earth.

Sometimes, though, there’s a different world lurking on the other side of that realm where visual images turn to mushy photons, so I reached for another dependable tool, a 6mm Astro-Tech Plössl. That eyepiece has always done an excellent job at controlling the glare in very glaring situations, such as this one.   And for who knows what reason, I was able to get its 408x image into focus – usually only briefly, but occasionally for several seconds at a time.

I sat patiently still, waiting and hoping for that magical secondarial sighting, while my tortured right eye grudgingly tolerated my obsession. After about fifteen minutes – I’m guessing since time becomes every bit as relative in this situation as Einstein predicted – I had an averted vision glimpse of something popping into view just inside the thick diffraction ring surrounding the primary.

Several times it leaped into sight and then slipped silently back into the primary’s high frequency twitch, and then re-appeared again.   After several of those teasing episodes, I grabbed the secondarial light with direct vision and held it for a couple of seconds:

Believe me, the image was nowhere near this stable.   (East & west reversed once again).

Believe me, the image was nowhere near this stable.  Click on the image to get a better view of the secondary. (East & west reversed once again).

Seeing conditions seemed to be improving slightly – either that, or my eyepiece eye and a secret compartment in my brain were getting better at cooperating with each other. At one point, I had the secondary in direct view for about ten seconds. It was a bit more than a puff of light – it had to be in order to be seen in the primary’s throbbing glare – but not quite what you would call a splendidly solid beam of light. At times there was almost a thinly transparent, surreal, quality to it.

But it was there – definitely, undeniably, unquestionably there – which was more than I had been able to say about the secondaries of Bu 1074 and Cou 1900 the year prior.

And as I sat there, mesmerized into a stellar stupor, I remembered another Herculean challenge – Zeta. But by the time I tore myself loose from Otto Struve’s 344th pair, the clouds began moving in, turning the sky into a featureless dark ocean. So I had to wait until the following night . . . . . . . and having wrestled unsuccessfully with Zeta numerous times the prior year, I reached for the 9.25 inch edge once again.

BUT – before you move your scope, we really should pan over to one of F.G.W. Struve’s nearby discoveries, Σ 2290, for a quick peek – it’s located a mere 18’ to the north. If you move OΣ 344 to the south edge of the field of view, Σ 2290 will come into view just slightly west of the north corner of the field. You can use 8.79 magnitude SAO 47230 to guide you in the correct direction.

Σ 2290         HIP: 88713   SAO: 30749
RA: 18h 06.6m   Dec: +50° 01’
Identifier                  Magnitudes          Separation        Position Angle        WDS
Cou 2276    Aa, Ab:  9.77, 10.00                0.30”                  13°                 1993
STF 2290         AB:  8.90, 11.20                3.90”                 352°                 2009
STF 2290         AC:  8.90, 12.70            178.00”                   69°                 2003
Distance: 2233 Light Years (Simbad)
Spectral Classification:  “A” is A5

The primary was a definite white, and the close-in eleventh magnitude secondary was easy to spot when the seeing cooperated and a real pain when it didn’t. The 12.70 magnitude “C” component, added to the system in 1880, is just a speck of light in the 9.25 inch SCT. You have to wonder why the 13th magnitude star one minute north of “C” wasn’t included at the same time.   (East & west reversed once more, click on the sketch for a much better version).

The primary was a definite white, and the close-in eleventh magnitude secondary was easy to spot when the seeing cooperated, and a real pain when it didn’t. The 12.70 magnitude “C” component, added to the system in 1880, is just a speck of light in the 9.25 inch SCT. You have to wonder why the 13th magnitude star one minute north of “C” wasn’t included at the same time. (East & west reversed once more, click on the sketch for a much better version).

Now that we have that one under our belts, we’ll move on to Zeta (ζ ) Herculis. If you’ve lost track of it, here’s the first chart once again.

Zeta (ζ) Herculis  (40 Her)  (Σ 2084)  (H I 36)
HIP: 81693   SAO: 65485
RA: 16h 41.3m   Dec: +31° 36’
Magnitudes: 2.95, 5.40
Separation:  1.186”
Position Angle: 145.5° (WDS 2014)
Distance: 35 Light Years
Spectral Classification: “A” is G0, “B” is G7
Note: Orbit and data can be seen here

I think it was Neil English, renowned guru of the long focus achromatic refractor, who first brought Zeta (ζ) Herculis to my attention — and here I was, attacking it with an SCT.   However, without giving too much away, after the evening with the SCT, I returned to the refractor fold with my six inch f/10 to get this wide field view of Zeta (ζ):

Again, a very sparse field, but enhanced marvelously by Zeta’s subtly hypnotizing gold/white glow that I find absolutely irresistible after two seasons of staring at it. (East and west reversed to match the refractor view).

Again, a very sparse field, but enhanced marvelously by Zeta’s subtly hypnotizing gold/white glow that I find absolutely irresistible after two seasons of staring at it. (East and west reversed to match the refractor view — click on the sketch to bring the gold glow to life).

To get back to the evening of June 23rd, I found the skies a couple of notches more cooperative, something close to a IV on this chart. I spent some time on other objects until close to midnight, which gave Zeta (ζ) plenty of time to get into position high in the sky and just west of the meridian. Once I located it and centered it in an 18mm Radian (136x), I went immediately to the 6mm Astro-Tech Plössl (408x) again. The image was more steady than the previous night, so it didn’t take long at all to realize the secondary was sitting out in the open, right at the outer edge of the first diffraction ring:

Apart from the welcome sight of the secondary, one of the things I quickly noticed was the pleasing gold/white photons characteristic of the low power view had been transformed into a thin, weak yellow.

Apart from the welcome sight of the secondary, one of the things I quickly noticed was the pleasing gold/white photons characteristic of the low power view had been transformed into a thin, weak yellow.  (East & west reversed, click on the sketch for a larger view).

I was amazed at how easy it was! I had tried and failed to split Zeta several times the previous year and here it was, just like that, on the first try. But now that I had the secondary in sight, I realized last year’s tantalizing teases were the real thing.  All those attempts had been under less than friendly seeing conditions, with so much jumping, whirling, spinning, and hopping that I could never be certain of what I saw.

When I returned to Zeta (ζ) a week later to get the wide field sketch with the 6 inch f/10 refractor, the seeing conditions were somewhere between the previous visit to Zeta (ζ) and the one to OΣ 344. I couldn’t resist the temptation to try again, so after I finished the 84x sketch, I reached for the 6mm AT Plössl (253x) once more to see what would happen. I had to look closely, but the secondary was definitely attempting to split off from the primary – what it needed was some help.

I grabbed a seldom-used 2.4x Dakin Barlow, slipped the 6mm AT Plössl into it, parked the whole thing in the diagonal, and then leaned over the unified pair and attempted to focus the blurred, vibrating image staring back at me. There’s one thing you just can’t miss when you blow up a yellowish 2.95 magnitude star to 608x – it’s dazzlingly bright. In fact, it seems to light up the whole field of view. With a very delicate touch on the two-speed focuser’s fine focus knob, I nudged the image toward what I hoped would be something resembling a focused star.

All the yellow-white light compressed into that diminutive five arc minute field was shimmering as though the star was about to erupt. Slowly, then suddenly, the image came into focus. I had to coax my eyepiece eye into reconnecting with the same secret compartment in my brain it had found on the night with OΣ 344, but after it re-established the connection, I could see through the glare to the secondary, sitting once more on the outer edge of the first diffraction ring with what looked like a mile of open space between it and the primary. OK – that’s a bit of an exaggeration caused by a temporary illusion and a very brief bout of insanity, but . . . . . . . . WOW! What a sight!

Double star nirvana! It seldom gets better than this! (East & west reversed once again).

Double star nirvana! It seldom gets better than this! (East & west reversed once again, click on the sketch to enlarge the gap between the primary and secondary).

William Herschel came up with a great phrase to describe the suddenly obvious distance between the primary and secondary at very high magnifications: “the distance is, as it were, laid open to the view.” You can almost see that thought materializing in his mind as he describes his experience with Zeta (ζ) on July 18th, 1782 (source, scroll down to the sixth title):

Notice those magnifications: 460x, 932x, and 811x! (The quote above is from the bottom of the same page as this observation).

Notice those magnifications: 460x, 932x, and 811x! (The quote above is from the bottom of the same page as this observation).

There’s nothing like the thrill of peering into the dazzle of magnified starlight and catching sight of a smaller secondary, very clear and very distinct, with black space between it and the primary, each of them vibrating, spinning, hopping, and leaping in unison – and around both of them, a diffraction ring shimmering so rapidly it appears to be spinning. It’s an electrical thrill that causes every quark in you to quiver (and probably quite a few outside you), and reminds you the sketch is only a snapshot of an experience quite literally out of this world.

Gotta go grab a small glass of something strong to calm the optic nerves now . . . . . . .

Clear (and stable) Skies!   😎  (Next time, back to northern Hercules again).

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6 Responses

  1. Hi John!
    Your poor tortured vision! I have to admire your tenacity. Another very enjoyable read. I hadn’t heard a lot of noise from the depths of the tall trees of Oregon…was thinking that the summer bulge of humanity in your quiet enclave had finally driven you out; but I see that that is not the case. I hope you are enjoying the summer!

    Cheers, Chris.

    • Howdy Chris,

      It’s probably a good thing the seeing here doesn’t allow a lot of high-powered star splitting. I suspect I would have a permanent visual diffraction ring affliction if that was the case.

      Prost!

      John

  2. Hi John,
    Another good read, last July I split Zeta with the 6inch reflector
    I found it difficult at 275x but just possible on good nights.
    I noticed in your sketch with the SCT the primary is white but
    with the Refractor it is yellow which is the real colour according
    to Simbad. On the night I split it it looked white to me. I would
    have thought the SCT and Reflector would have shown a more
    true colour than the Refractor interesting .

    Pat.

    • Hi Pat,

      Actually, the two sketches should be closer in color, but the difference is a result of the way the software processed the colors while adjusting the contrast and sharpness.

      In general, I find the colors in the SCT to be more harsh and cold, whereas that of an achromatic refractor is a definitely warmer and more pleasing to the eye (at least mine, anyway).

      John

  3. John,

    Another great tale of double’s chasing! Have you ever considered doing a column on how you transfer your sketches into the electronic realm? I for one would be considerably interested in how you put them together.

    Mike

    • Hi MIke,

      Thanks for the compliment!

      I hadn’t thought about a post on how the sketches are done, but I’ll look at doing one sometime in the future. In the meantime, I can give a short description of how it’s done.

      First, I draw the star fields on a piece of white paper with a circle of about two inches in diameter. I’ve found anything larger is hard to work with under red light in the dark. I also add all my notes to that piece of paper, such as colors, relative brightness of primary and secondary to each other, diameter of the glow around the primary, seeing conditions, etc.

      Then I transfer the sketch to the computer using MIcrosoft’s Paint program, which I also use to add the labeling and other details. I use another program, Paint.net (available on the internet as shareware) to add some of the colors, but mainly to add the glow around the brighter stars and to adjust the contrast. Paint.net is similar to Gimp, and has a lot of features found in commercial programs such as Photoshop Elements.

      As for the diffraction rings, I’ve always found that to be a real challenge. On the two stars in the post above, Zeta Hercules and STT 343, I experimented with using diffraction rings from an internet article on optics, which gave me something to start with. It took a lot of cutting, pasting, and shading to adapt the appearance of the rings to what I saw at the eyepiece. I spent about an hour or so on each of the sketches with diffraction rings in order to get them as close to the eyepiece image as possible, and then went back and re-worked them later because I wasn’t satisfied with them. There has to be a better way, but I haven’t found it — yet!

      John

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