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The Subtleties of Starlight in Cygnus, Second Part: S 790 and H IV 113

(If you ended up here without reading Part 1 of this binary post, you can reach it by clicking on this link).

From Upsilon (υ)/OΣ 433, look north with a lean toward the east, for a distance of two degrees and you’ll see three points of light. The middle one is our goal, S 790. The first one you come to is actually an open cluster, NGC 7063, which will probably resemble a star in your finder; the star on the other side of S 790 is 5.3 magnitude 70 Cygni. (Stellarium screen image with labels added, click to enlarge).

S 790  (69 Cygni)  (H V 44 — AC only)       HIP: 105811    SAO: 71329
RA: 21h 25.8m   Dec: +36° 40′
*****      Magnitudes       Separation       Position Angle        WDS Data
AB:           5.9,  11.7               34.3″                      29°                       1999
AC:           5.9, 10.2                53.3″                      99°                       2003
Distance:  2764 Light Years
Spectral Classification   A: B0
Status: Undetermined

So there I was, standing beneath a full moon once again, with the six inch f/10 pointing skyward and a 12mm Radian (127x) at home in the diagonal.  And when it was time to take a look, I found the primary was your basic white, with “B” and “C” arrayed perfectly around it, both easy to see despite the scattered moonlight.

A quite, peaceful, orderly view — east & west reversed, click to lose the caption.

Now the 12mm view is just what the sketch shows — very neat and very crisp, what I call a “quiet” view.  There’s really nothing else in the field of view to divert your eye from the main attraction, and while it’s not colorful, there is something about the three stars at the center that strikes me as rather orderly.  The primary is bright, but not overwhelming, and glows with very little glare.  “C” catches your eye next because it’s almost a full magnitude and a half brighter than “B,” and then “B” announces itself very distinctly in its slightly fainter voice.  The location and position of “B” adds some dimension to the view — if only the primary and “C” were present, this would just be a comfortably spaced pair of stars.  And I think that’s the essential charm of a well-spaced triple star — a third star adds just enough visual interest to make the view in some way distinctive.

But I craved more magnification after that last adventure with Upsilon (υ), and my ever ready four-legged observing partner already had it ready.  He forked over that old dependable black, orange, and chrome-colored standby, the 7.5mm Celestron Plössl (203x), which I placed in the diagonal with care, focused with even more care ……… and as clarity materialized, was transported several hundred light years closer — which had the predictable effect of removing about half of the previous field of view, as well as making the primary’s white color quite a bit stronger.  And since there was nothing else to be seen, my attention was firmly focused on those three beckoning, shimmering points of light whose photons started in my direction 2764 years ago.

Sir James South recorded his first observation of this trio on October 2nd, 1824 — “Double; 6th and 12th magnitudes.” — on a “Night very favourable.”  He didn’t provide any description of color, but Haas includes this description: “Heckman, 250mm, 96x: An ‘easy blue pair with a large magnitude contrast.’ ”

NGC 7063, STScI photo, click to enlarge

Now  —-  don’t rush off!

Before you leave this area, be sure to take a long look at NGC 7063, just out of view at the south edge of the field — it’s a pleasantly small and comfortable grouping of about a dozen stars in an 18mm Radian (84x), well worth a sketch sometime.

The photographs I’ve seen just can’t catch the visual magic of this scattering of stars, but this STScI photo provides some idea of it at least.

*********************************

And now, on to the pièce de résistance!

To get where we’re going next we need to make about a ninety degree turn to the west, which will take us first to Tau (τ) Cygni, two degrees away (also a double with a .7″ separation and magnitudes of 3.8 and 6.4), and then to 61 Cygni, another one and a half degrees beyond it. Our target, H IV 113, is another degree beyond that and very slightly north of the line we’ve been traveling. If you look closely at the chart, you’ll see it’s the first of two fainter stars on the path to fourth magnitude Nu (ν) Cygni. H IV 113 shines at a combined magnitude of 6.45 and its slightly fainter neighbor on the way to Nu (ν), HIP 103641, maintains a magnitude of 6.60. (Stellarium screen image with labels added, click to enlarge)

And  ………..  I’ll let you in on a small secret — I almost never got this far.  I stubbed my stellar toes, so to speak, on 61 Cygni and almost didn’t get up.  If you’ve been following along with me at a telescope, you no doubt noticed 61 Cygni shining with a very ethereal orange duality.  We won’t dwell on it now — Greg has a post on it here — but yes, it’s a wonderful sight, and I wouldn’t blame you a bit if you get stuck here for an hour or two.  For a beautifully rendered sketch of 61 Cygni, you might want to take a look at this one by Jeremy Perez, from his web site, The Belt of Venus.

H IV 113 (Σ 2748)       HIP: 103822    SAO: 70818
RA: 21h 02.3m   Dec: +39° 31′
*****                 Magnitudes         Separation       Position Angle      WDS Data
AB:                       6.6,    9.5                 19.2″                     299°                   2006
AC:                       6.6, 12.5                 26.6″                     248°                   1999
AD (SMY 6):        6.6, 12.5                 57.0″                     140°                   2000
AE (    ”    ):          6.6, 10.9                 96.2″                        87°                   2000
AF (WRD 1):       6.6, 11.9               101.6″                     223°                   2000
Distance: 1142 Light Years
Spectral Classification   A: K3
Status: AB gravitationally linked (Haas), others undetermined

But once I cleared those twin orange beams of light from my head, I thought I might as well stumble another degree north to the 113th star in Sir William Herschel’s catalog, and when I got there — as a former New York Yankee catcher and manager said many a time — it was déjà vu all over again.

Because as soon as I feasted my eyes on the primary, I found myself breathing in the aroma of that deep 61 Cygni orange — all over again.  Remarkable.  If I didn’t know better, I would swear these two systems were trading photons back and forth.  But 61 Cygni is only 11.4 light years away from us, so with a difference of over 1000 light years between the two systems, I suppose not.  On the other hand, just think for a moment about how bright that Herschellian primary would be if it was the one sitting 11.4 light years away from us.

But I digress once more — let’s get focused here!

. . . give those colors the chance to work on your eyes . . . begin to appreciate that they really are very attractive in close combination. (East & west reversed again, click for a view without this caption).

And once I finally got everything precisely focused, I was confronted with a complex and colorful combination of multiple pinpoints of star light.  With a dark, moonless sky for a backdrop, my 111mm Astro Tech refractor showed just a hint of white in that deep orange primary at 130x, and the secondary nestled up beside it displayed a faint, but very obvious, blue — and the two colors in combination were enough to bring a tear to the eye of even the most photon saturated Star Splitter.

I could see the weak eleventh and twelfth magnitude glows of “D,” “E,” and “F,” but “C” was just too darn close to the primary for it’s 12.5 magnitude photons to reach me.  So I doubled the magnification by using a 6mm AT Plössl in a 2x Barlow, and at 260x, “C” emerged into the photonic main stream with the others.

Sir William Herschel came across these stars on January 6th, 1783, and made this note on them: “Very or extremely unequal. L. r.; S. db. A third star in view. [Rho = 17″, PA = 298°]”  I think the translation of his letters is “Large red; Small dark blue.”  And you may have noticed the position angle and separation he measured are barely different from the WDS data of 2006 — so it would seem there isn’t a lot of motion here.

Admiral Smyth took a look at these stars in 1832, and apparently picked out most of the fainter group now labeled as “C” through “F”  —-   “. . . there are several telescopic pairs in the field, of which one in the sf  [south following], of the 13th magnitude, is sufficiently near to form with “A” and “B” a triple object.”   —-   that last apparently a reference to “D”  —-  and described the AB pair as “deep yellow” and “emerald hue.”  (The Bedford Catalog, p. 493)

Haas was just as colorfully precise in her description of the AB pairing: “125mm, 50x: Lovely pair of stars — bright yellowish apricot and dim sky blue.  They’re attractively close while wide enough to be easy.”

For some variety, you might take a shot at splitting “E,” which is actually a triple.   The data for EC is 95.0″ of separation at a position angle of 230 degrees, with the secondary barely burning at a weak 13.7 magnitude; and for EH, the numbers are a separation of 35.0″, a PA of 140 degrees, and a magnitude for “H” of 12.1 — and according to the WDS, no one has reported any data on this triple since 1875.  You’re going to need large aperture for this — probably more than six inches — but here’s your chance to make a contribution!

To return to the phrase I used at the beginning of this rambling tour, it was the “delicate aesthetic appeal” of these five multiple stars that impressed me — and  H IV 113 is well suited to that description if you look at it closely.  Because of the magnitudes, the colors of “A” and “B” aren’t going to blast your eyeballs with exploding photons — but when you take the time  (there’s that word once again) and give those restrained colors the chance to work on your eyes and your mental apparatus, you begin to appreciate they really are very attractive in close combination.

And notice how “C”, “F”, and the next unlabeled star beyond “F”, form an evenly spaced line of faint stars pointing directly into the gap between the primary and secondary.  And “F”, “D”, and “E” form another line of evenly spaced stars, not quite as straight, but still another stellar vector aimed east and west into the fathomless reaches of interstellar space, pointing to who knows what unimaginable sights.

********************************************************************************************

We’ve soaked up a lot of subtle starlight here — an over-abundance perhaps if you lingered over 61 Cygni — but certainly enough that I hope in some small way you’ve absorbed a feel for the kind of thing I’ve been describing here.  Think of it in these terms:

In order to appreciate a soup that simmers all day on the stove on a cold winter day, or a mellow old Port on a cold rainy evening, or the wonder of Mahler’s Third Symphony late at night  —-  or the subtle beauty of multiple pulsing points of faint starlight strewn across a pitch black sky   ——–   you have to be patient.

Sip that soup slowly and inhale its aroma   …………..   swirl the Port around in your mouth and let the taste linger on your tongue    ……………….    close your eyes as the soprano’s voice in the fourth movement of Mahler’s Third soars into the heavens and tugs at your emotions    ………………………….     stare carefully and patiently into the eyepiece of your telescope with a calm, clear head.

Otherwise, you’ll end up hopping quickly from one object to the next and never open yourself up to the mystery and the delicate aesthetic beauty of those countless points of light up there in that dark sky.  It’s all there, waiting for you to peel back the very thin veneer that covers it.

And thin though it may be, it doesn’t peel back quickly.   But when you succeed, it’s seriously unheimlich.

********************************************************************************************

There’s still one heck of a whole lot more to be seen in this area of Cygnus. If you turn to chart number eleven in The Cambridge Double Star Atlasand follow along the spine of Cygnus from Albireo to just past Deneb, you’ll see the Herschels, James South, and Wilhelm and Otto von Struve spent a lot of time up here — shadowed, no doubt, by Admiral Smyth.  There’s a lot of history, a lot of stellar beauty, and a lot to think about in this small sector of the sky — so I do believe I’ll be back.

Stay tuned  ………..  and Clear Skies!  😎

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Additional information on sources:

I’ve been searching for complete listings of the observations of both F. G. W.  von Struve (the stars that carry a prefix of Σ) and Otto von Struve (his carry the prefixes OΣ and OΣΣ), and finally came up with two very helpful books, both of which are in the public domain and can be downloaded or viewed in Google Books.

First, this one lists all of  F. G. W. von Struve’s observations:  Measures of the Double Stars Contained in the Mensurae Micrometricae of F. G. W. Struve, Collected and Discussed with an Introduction Containing General Deductions, a List of Proper Motions of Fifty Faint Stars, and Various Other Information in Respect to Double Stars by Thomas Lewis: Royal Astronomical Society, London: Burlington House, 1906.

And this one lists all of Otto von Struve’s observations in his 1843 Pulkova catalog (the OΣΣ supplement is not included here):  Micrometrical Observations of the Double Stars Discovered at Pulkowa made with the Thirty-Six-Inch and Twelve-Inch Refractors of the Lick Observatory together with the Mean Results of the Previous Observations of these Stars  by J.W. Hussey: Publications of the Lick Observatory of the University of California, Volume V, 1901, Sacramento.

The great thing about both books is each listing also includes most, if not all, of the known observations by various observers up to the publication dates of each of the books.  What that means is both of them are great sources for locating the late 17th and early 18th century observations by William and John Herschel, James South, and Admiral Smyth, as well as others.  Although most of the descriptions of the stars by both Struves is cryptic, the list of prior observations also includes the dates they were made, the separations, and the position angles.  So at one glance, you can see a quick history of the motion that occurred over roughly a one hundred year period.

Neat.

I’ve listed sources for John Herschel and James South in previous posts — for John Herschel go here and for James South go here, and for the joint James South-John Herschel observations of 1821-1823, which carry the prefix “Sh”, go here (scroll to the bottom of the page).

And for William Herschel’s observations, I can’t recommend this web site strongly enough:  The William Herschel Double Star Catalogs Restored.    The complete Herschel catalog is here:  William Herschel’s Double Star Catalog, and can also be reached from the first link.

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