Note at the beginning: Many of these posts rely on the help and input of other people, which is especially the case for this one. So before we get started, I want to extend my thanks to Brian Mason and Bill Hartkopf at the USNO/WDS for their help. Brian sent me the HJ 1352 text file and a link to some valuable data I’ll use at a later date, and Bill Hartkopf was a huge help in making sense of the proper motion of HJ 1352, even going to the trouble of generating a new rectilinear chart of HJ 1352’s motion. I couldn’t have done this one properly without their input. It would be impossible to overstate the importance of these two guys to those of us who observe, measure, or write about double stars.
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Considering the relatively small parcel of celestial real estate covered by Lyra, it seems to be rather well stocked with a large collection of double and multiple stars. If you start from any one of the four corners of the constellation, or from the apex at Epsilon (ε), you don’t have to go far before you find you’re surrounded by a maze of multiple points of light, many of them carrying double star designations.
For some reason Beta (β) Lyrae, aka Sheliak, caught my attention one night and, lured by the dual lighthouse-like beams radiating from Nu-1 (ν-1) and Nu-2 (ν-2) just south of Sheliak, I began to wander through the area. In fact, it was such an enjoyable stroll that I came back later and wandered around west of Sheliak/Beta (β). We’ll cover the southern stellar terrain in this tour and then look at what’s west of Beta (β) on the next tour.
First, let’s get oriented:
And then let’s take a closer look at the area south of Sheliak:
Nu-1 Lyrae (H V 40) (8 Lyrae) HIP: 92398 SAO: 67441
RA: 18h 49.8m Dec: +32° 49’
|H 5 40 AB:||5.93, 10.89||34.10″||76°||2009|
|H 5 40 AC:||5.93, 10.30||57.50″||120°||2009|
|WAL 95 AE:||5.93, 11.64||80.00″||350°||2008|
|WAL 95 AF:||5.93, 12.92||70.60″||349°||2002|
|H 5 40 CD:||10.30, 11.50||18.80″||212°||2008|
|Distance: 1309 Light Years (Simbad)|
|Spectral Classification: “A” is B3|
With six components, Nu-1 (ν-1) is a mesmerizing visual experience. I used a 9.25 inch SCT for the sketch below, but easily could have gone with as little as five inches of aperture, possibly even four, and still captured all the members of the tribe except for the difficult 12.92 magnitude “F”, which suffers from being within ten arc seconds of 11.64 magnitude “E”.
The star he describes as north (n.) preceding is “B” and the south (s.) following is “C”, which is also the star he provides measurements for. His 28° 27’ s. following translates to today’s 118° 27. Surprisingly Herschel missed (or ignored) “D”, which we’ll come back to in a moment. The last two components were added by A. Wallenquist, a Swedish astronomer, who uncovered “F” in 1934 and “E” in 1944.
If you look closely at the southwest edge of the sketch above, you’ll see a faint and shadowy pair, which is ES 2287 (18493+3301, 10.9 and 12.3, 3.9”, 293°, WDS 2011), discovered by T. E. Espin in 1927. The secondary didn’t appear to me to be 1.4 magnitudes fainter than the primary as per the WDS data, but even the UCAC4 catalog (enter UCAC4-616-064988 in the box labeled “ID”) shows a magnitude of 12.489 for it. At any rate, it’s difficult to visually separate this pair because of their overall faintness and tight separation.
Getting back to Nu-1’s 11.50 magnitude “D” component, it looks as if Admiral William H. Smyth should be credited with first putting that star under a micrometer. He measured the CD separation at 12.0” in 1836 with a PA of 208 degrees. Since he hasn’t made an appearance here for a while, I’ll let him describe Nu-1 and get us started towards Nu-2 (ν-2). His magnitudes, which are considerably different than today’s, follow the letter designation of each star.
A quadruple star on the cross-piece of the Lyre. “A” 6, pale yellow; “B” 13, bluish; “C” 11, pale blue; “D” 15, blue; and there are three other stars in the field. This object is 40 H V, who only measured “A” and “C”, though perceiving “B” and not “D”; he records it as triple. Sir James South, who appears not to have seen “B” or “D”, also observed the stars “A” and “C” . . .
This very delicate set is followed by ν2 Lyrae, a whitish star of the 6th magnitude, at an angle of 175°, and a distance of about 15’ of space; and they are both just to the south of β, the following object.” (The Bedford Catalogue, pp. 432-33)
Nu-2 Lyrae (HO 440) (9 Lyrae) HIP: 92405 SAO: 67446
RA: 18h 49.9m Dec: 32° 33’
Magnitudes: 5.25, 12.70
Position Angle: 175° (WDS 2002)
Distance: 238 Light Years
Spectral Classification: “A” is A3
After reading Admiral Smyth’s description of Nu-2, it appears he didn’t see the secondary, which was also missed by William Herschel and James South. It wasn’t until 1892 that someone caught sight of it, that someone being George W. Hough, who did it with the 18.5 inch Clark refractor at the Dearborn Observatory. As you can see by his comment in the excerpt above (source), even with that much aperture he had a difficult time spying the secondary.
Now we’ll move on to Σ 2397, which lies south and slightly west of Nu-2 (ν-2) at a distance of 1° 17’. You can use 6.05 magnitude HIP 92243, which is 54’ south of Nu-2, as a stepping stone to find your way. (Here’s the second chart above once again). I also labeled HIP 92396 (magnitude of 6.60) and HIP 91883 (magnitude of 5.65) on that chart, which come in handy as reference points.
Σ 2397 HIP: 92178 SAO: 67378
RA: 18h 47.2m Dec: +31° 25’
Magnitudes: 7.47, 9.08
Position Angle: 266° (WDS 2011)
Distance: 883 Light Years (Simbad)
Spectral Classification: “A” is G3
This pair was discovered by F.G.W. Struve in 1830, and they haven’t changed much since his original measurements of 3.72” and 267.4°, as you can see by comparing both the current WDS data and the various measurements shown at the right which followed those of Struve (from Thomas Lewis’s 1906 compilation of data on Struve’s discoveries). The lack of significant change is reflected in the proper motion numbers for the primary and secondary, which are identical, +001 +016 (.001”/year east, .016”/year north). These two stars are essentially moving through our galaxy in tandem, and provide an excellent example of a double star which is physically related, but not orbital.
Our next stop, Σ 2367, shining southwest of Σ 2397 at distance of 1° 42’, is a little tougher to get to. (Here’s the chart once more). If you aim a line from Σ 2397 that runs midway between 7.55 magnitude HIP 92129 and 6.40 magnitude HIP 91533, it’ll point straight to Σ 2367.
Σ 2367 HIP: 91636 SAO: 67250
RA: 18h 41.3m Dec: +30° 18’
|Distance: 530 Light Years|
|Spectral Classification: “A”, “B”, and “C” are all G5|
|Notes: Orbital period of AB is 93 years; AB,F is also BTG 2|
This one was quite a sight when I first laid eyes on it. Your observational eye is immediately drawn to the two brightest stars in the field, 7.70 magnitude AB and 8.75 magnitude “C”, which actually stands in as the visual secondary in this case since the true secondary is hiding in the primary’s glow at a too-close-to-crack distance of 0.42”. There’s a plot of the 92 year orbit of AB in the WDS (shown here from the Stelledoppie page), which includes the separation and position angle I listed in the data above. If you have enough aperture, and cooperative seeing, this would be a great pair to attempt to split since they’re almost identical in magnitude. Lewis has an interesting diagram which comes close matching the WDS.
You have to look harder and closer to catch sight of twelfth magnitude “D” (I needed averted vision to see it) and eleventh magnitude “E” because of the glare caused by the AB,C pair. After identifying “E”, I couldn’t help but wonder why that faint star to its north (right in the sketch) wasn’t included in the measurements for the stars surrounding AB-C, especially since a fifteenth magnitude star was added as “F” in 1998.
Also lying in the same field of view with Σ 2367 is an unexpected bonus, HJ 1336, an intricate and dim collection of stars in an interesting arrangement. When I first saw them, I found them rather striking, despite their faint magnitudes . . . . . . .
HJ 1336 No HIP SAO: 67236
RA: 18h 40.5m Dec: +30° 17’
|Spectral Classification: “A” is A0|
. . . . . . . but I wasn’t sure if I was looking at a small cluster or a multiple star. I had to go back to Sky Tools 3 and Stelladoppie to find out what I was looking at. I missed twelfth magnitude “B” entirely on that first view, so I came back later with the six inch f/10 refractor and pried it out of the darkness with a 10mm Radian (152x). I also tried my trusty 7.5mm Celestron Plössl (203x), but the murky air and poor seeing made the 10mm Radian a better choice, although I needed averted vision in both cases to detect it.
The eleventh magnitude (“11 m”) star Burnham refers to on the last line is the AD pair that Herschel discovered. Herschel’s observation of HJ 1336, which refers to that pair as AC, is shown below in the discussion of HJ 1352. As you can see, there are times when you really need a scorecard to keep track of what went where when the identifications of components change as additional stars are added to a system.
Last on this tour is HJ 1352, which again requires some careful navigation (our chart once more). It lies one and a half degrees east and slightly south of Σ 2367. The only reasonably bright star along the way is 8.45 magnitude HIP 92261, which is a full degree east and a bit south of Σ 2367. You can also use 7.55 magnitude HIP 92129, which lies a bit more than a degree (1° 12’) east and very slightly north of Σ 2367, as a reference point. Either way, you’ll find HJ 1352 occupying the north end of a string of eighth magnitude stars aligned in a northwest-southeast diagonal.
HJ 1352 HIP: 92419 SAO: 86484
RA: 18h 50.1m Dec: +29° 49’
Magnitudes: 7.8, 10.0
Position Angle: 249° (WDS 2006)
Distance: 1105 Light Years (Simbad)
Spectral Classification: “A” is B8
“Bears a singularly bright illumination.”
Those are John Herschel’s words, and as the sketch below shows, the primary stands out distinctly from the rest of the field:
This is another 1828 discovery by John Herschel — his observation is shown below at the bottom of the page (source):
Even though Herschel included the comment “Well measured”, it’s likely the separation (6″) was estimated. If we look in Burnham’s 1906 Catalog , we find measurements by Otto and Hermann Struve’s from 1879 and 1885 which cast a doubtful light on that six arc second figure:
And if we jump ahead to 1909, we find S.W. Burnham’s efforts (source) confirm the Struve measures — but notice the four degree change in position angle, which Burnham comments on :
Curious about that rapidly changing position angle, I sent a request to Brian Mason for the text file listing all the measures for HJ 1352 from 1828 to the most recent in 2006, and used the data to generate a chart showing the changes over that 178 year period. There were a cluster of five measurements between 1906 and 1918, and three each in 2002 and 2006. To avoid cluttering up the chart below with dots stacked on top of one another, I averaged each of those clusters to come up with one measure for each time period, resulting in this plot:
You can see the secondary is steadily moving both north and west, which in fact is exactly what the proper motion figures show: -017 +005 (.017”/year west, .005”/year north). On the other hand, the primary, with a proper motion of +003 -001 (.003”/year east, .001”/year south), is hardly moving at all .
When we compare HJ 1352 with our earlier discussion above of Σ 2397, we find although the directions are different, the rates of motion are very similar: +001 +016 (.001”/year east, .016”/year north) for the Σ 2397 pair and -017 +005 (.017”/year west, .005”/year north) for the HJ 1352 secondary. The main difference is the primary of HJ 1352 is virtually stationary, so about 99% of the change in position angle and separation is a result of the secondary moving away from the primary. Which is a pretty darn clear indication the two stars aren’t physically related in any way.
Amazing what a few numbers can tell you about a pair of stars!
Next time out, we’ll start at Sheliak again and head due west to see what we can find.
Clear Skies until then! 😎