Ahhhhh, there’s nothing like a sip of cold water on a hot summer day . . . . . . . . but if you’re waiting for water to flow from the Aquarian water jar, you’re likely to be well past parched by the time Aquarius hoists his massive framework into the heavens. Still, even though the Aquarian may be a little late for thirsty lips, he nevertheless has one other redeeming quality: a penchant for pouring starlight out of that jar tucked under his right arm.
As an informative aside, the German language has a much more descriptive name for Aquarius: der Wassermann — which, if it isn’t obvious, translates as The Water Man. At any rate, flowing from The Water Man’s jar are the three main stars of this excursion: Bu 1515 (60 Aqr), HJ 5529 (Kappa/κ Aqr), and Bu 172 (51 Aqr), which are mapped into their respective places on the left side of this chart:
Mainly an autumn constellation, Aquarius hangs around into the beginning of winter provided you get outside when the December dusk descends. But before we look at a the three main attractions for this tour, it would really be inexcusable to pass up an opportunity to take a short peek at the real star of Aquarius, Zeta (ζ).
Zeta Aqr (55 Aqr) (Σ 2909) (H II 7) HIP: 110960 SAO: 146107
RA: 22h 28.8m Dec: -00° 01’
|EBE-1 Aa, Ab:||4.34, ????||0.65″||147.8°||2014|
|STF 2909 AB:||4.34, 4.49||2.247″||164.9°||2015|
Greg has already covered Zeta (ζ) rather well in a previous post (be sure to continue into the comments section for more discussion), so I’ll keep this brief and to the point: this is one of the genuine gems of the ecliptic.
We’ll get this excursion started with Bu 1515, also known as 60 Aquarii. It’s an easy one to find: starting at fourth magnitude Eta (η) Aquarii, drop a degree and a half south and just slightly west (here’s our previous chart once again). For reference, Bu 1515 is parked halfway between Eta Aqr and 6.15 magnitude HIP 111171.
Bu 1515 (60 Aqr) HIP: 111394 SAO: 146160
RA: 22h 34.0m Dec: -01° 34’
Magnitudes AB: 5.98, 11.54 AC: 5.98, 11.89
Separations AB: 99.80” AC: 126.60”
Position Angles AB: 298° (WDS 2000) AC: 275° (WDS 2000)
Distance: 347.5 Light Years (Simbad)
Spectral Classification: “A” is G6
Anyone familiar with S.W. Burnham’s double star discoveries is aware the title of his 1900 catalog of discoveries, A General Catalogue of 1290 Double Stars Discovered from 1871 to 1899, tops out at Bu 1290 – hardly a surprise, of course . . . . . . . which raises the question of where the numbering for Bu 1515 came from. Again, it should come as no surprise that Burnham continued to discover double stars after the publication of that catalog, so the numbering continued. (From what I can determine, it ends at Bu 1540). The origin of the Bu 1515 designation, though, is a bit vague. After my internet roaming failed to turn up an answer, I got in touch with Brian Mason at the USNO/WDS, who not only provided me with an answer, but also a link to the source.
The source is a four page article published in the July 5th, 1918, issue of The Astronomical Journal, in which Burnham is listed as the author. Although the data in the article is his, the four page article was actually put together by Philip Fox, who had been entrusted by Burnham with a list of unpublished double star measures.
In 1932, when R.G. Aitken published the successor to Burnham’s 1906 double star catalog, he apparently dropped Burnham’s listing. (The Aitken catalog is referred to today as the ADS – the actual title is New General Catalogue of Double Stars). Nevertheless, the observation remained assigned to Burnham, although with no designation. The Bu 1515 designation first showed up in a 1996 edition of the Washington Double Star Catalog (WDS), which led Brian to conclude it was added by Charles Worley, who first had responsibility for the WDS as we now know it. As to how that number was arrived it, we may never know.
Before we leave Bu 1515, there’s an unexpected triple star bonus, Bu 77, parked in the south corner of the view. Here’s the WDS data on this threesome:
Bu 77 No HIP or SAO Numbers
RA: 22h 34.0m Dec: -01 47’
Magnitudes AB: 9.31, 9.92 AC: 9.31, 10.80
Separations AB: 2.60” AC: 25.30”
Position Angles AB: 215° (WDS 2010) AC: 230° (WDS 2010)
Distance: None found
Spectral Classification: “A”is F0
I caught the 10.80 magnitude “C” component, but the 9.92 magnitude “B” companion escaped me since I wasn’t aware Bu 77 was in the field until after I had made the sketch above. S.W. Burnham first captured this triple in 1872 with his six inch f/15 Clark refractor.
Meanwhile, on to another mystery, HJ 5529, aka Kappa (κ) Aquarii. You’ll find it just short of three degrees south and slightly east of Bu 1515, where it shines distinctly. Here’s our last chart again.
HJ 5529/Kappa Aquarii (63 Aqr) HIP: 111710 SAO: 146210
RA: 22h 37.8m Dec: -04° 14’
Magnitudes as of Sept. 14th, 2014: 5.00, 8.8
Magnitudes as of Dec. 22nd, 2014: 5.18, 12.2
Position Angle: 256° (WDS 2010)
Distance: 234 Light Years
Spectral Classification: “A” is K2
Note: High PM for primary: -069 -120 (WDS and Simbad); secondary at +043 +007
When I first bent down to the 12mm eyepiece lodged in the diagonal of my six inch refractor, I anticipated a very obvious secondary parked to the west of the primary, but that wasn’t quite what happened. Instead, I found myself peering into the depths of the west side glare for a glimpse of secondarial light. It took a few seconds, but once I captured it visually, I had little trouble keeping it in view. The surprising absence of a brighter star initially baffled me until I realized it wasn’t my eyesight, but an oversight – of some sort.
But of what sort was the question.
The secondary is decidedly fainter than the WDS magnitude of 8.8. On the other hand, the UCAC4 “f” magnitude of 12.124 struck me as too faint (mainly because of the glow coming from the primary), as did the Nomad-1 “Vmag” of 12.180. However, combining the “J” and “K” magnitudes for the secondary in the UCAC4 data resulted in a visual magnitude of 12.111, so despite my reservations, all indications pointed to the 12.1 to 12.2 range. A comparison with nearby TYC 5236-01401-1, which appears slightly brighter in both my sketch and the Aladin color photo just below it, also seemed to point to the 12.1 to 12.2 magnitude range for the secondary, although I still had concerns as to what extent the primary’s glow might be causing the secondary to appear a bit fainter than it actually was.
I aimed my research through cyberspace to reach Bill Hartkopf at the USNO/WDS, who very quickly answered in less than half an hour. After making similar magnitude comparisons, and looking at images of HJ 5529/Kappa (κ) Aqr on red and blue plates, he leaned toward the Nomad-1 “Vmag” of 12.18. He also made a small change in the magnitude of the primary, from 5.0 to 5.18.
All of which explains why there are two lines of magnitudes listed in the data above for HJ 5529/Kappa (κ) Aquarii.
But there was yet another surprise lurking in the dark, waiting patiently to reach out and grab me when I least expected it.
A Case of Mistaken Identity
The proper motion of HJ 5529 A is rather significant at -069 -120 (.069”/year west, .120”/year south) . . . . . . .
. . . . . . . which prompted me to see if S.W. Burnham had commented on it in his 1906 catalog. So there I was again, staring semi-somnolently (this time at a computer screen, not into an eyepiece), when I was jolted from lethargy to a loss of words:
“I have never been able to see any trace of the small star in the last thirty years.”
But I certainly saw it — not to mention it being clearly visible in the photos . . . . . . .
When in doubt (or somewhat stunned), go to the source:
“An exceedingly minute point strongly suspected.”
Which explains the origin of the quote at the beginning of Burnham’s catalog entry.
But as I looked at John Herschel’s observation more closely, I noticed the position angle and distance were decidedly discordant with the current measures . . . . . . . and then I realized there were no magnitudes shown.
I aimed my new discovery through cyberspace with instructions to land in Bill’s in-box, which it did. He researched a bit further and found this entry in Burnham’s 1913 Proper Motion Catalog:
“ . . . has never been seen since and certainly does not exist.”
But at least this entry by Burnham included measures of Kappa (κ) Aquarii, which meant Burnham had seen something. In fact, if you compare his measures with the most recent 2010 data in the WDS, you’ll notice a significant difference between the two, which is attributable to the considerable proper motion of the primary.
As to what Herschel was looking at when he assigned a catalog number of 5529, we’ll probably never know. It’s possible the 12th magnitude secondary would have been very difficult to detect with the twenty inch mirror Herschel used at the time, but his measures seem to indicate he was looking at another star entirely — and the absence of magnitudes makes it even more impossible to figure out what he might have been looking at.
We may also never know where the 8.8 magnitude of the secondary in the WDS originated. Bill sent me the text file for HJ 5529/Kappa Aqr, which shed no light whatever on the origin of that magnitude. But what it did show is S.W. Burnham was the first person to actually make and publish measures of Kappa (κ) Aquarii. (There was an 1896 measure by P. L. Gauchet, 246.4° and 103.11”, which wasn’t published until 1926). So credit for the double star status of Kappa (κ) Aquarii should go to Burnham, and as for HJ 5529 – wherever and whatever it originally was, it wasn’t Kappa (κ) Aquarii.
Now on to the last of our four stars, in which the ever-present S.W. Burnham also had a hand – and it also is a puzzle of sorts. Bu 172, aka 51 Aquarii, is less than a finder field (8×50) away from Kappa (κ) Aquarii. Here’s our last chart again, which shows it three and half degrees west and slightly south of Kappa (κ). A closer look reveals it’s roughly halfway between Kappa (κ) and 5.75 magnitude HIP 110023. You can also use the three stars surrounding 5.98 magnitude HIP 109466 for a reference point, as well as 5.35 magnitude Rho (ρ) and 4.16 magnitude Theta (θ) Aquarii.
Bu 172 (51 Aqr) HIP: 110578 SAO: 146067
RA: 22h 24.1m Dec: -04° 50’
|Bu 172 AB:||6.45, 6.63||6.45, 6.63||0.46″||36°||2014|
|Bu 172 AB,C:||5.77, 10.10||5.77, 12.20||53.10″||343°||2005|
|Bu 172 AB,D:||5.77, 10.00||5.77, 11.50||123.30″||191°||2002|
|Bu 172 AB,E:||5.77, 9.87||5.77, 9.87||130.30″||133°||2002|
|STU 14 AB,F:||5.88, 8.50||5.77, 11.10||256.80″||3°||2000|
Distance: 424 Light Years
Spectral Classification: “A” is B9.5
Notes: AB,C is H V 95; AB is binary (orbit is here); AB,C is physical; D and E are optical.
Once again I found myself looking at a multiple star with magnitudes that didn’t quite match the published numbers, but this time I was expecting it. Peter Morris had sent me two descriptions of Bu 172 earlier in the year, pointing out “F” was much fainter than the 8.50 magnitude assigned to it, and also calling attention to magnitude discrepancies in the “C” and “D” components. Within a few days of receiving Peter’s second description, I pointed my six inch f/10 refractor at Bu 172 and found his description right on target.
Again I called on Vizier for advice and leaned on the UCAC4 and Nomad-1 catalogs for support:
My eyes were first drawn to the UCAC4 and Nomad-1 magnitudes for “F” – UCAC4 has it at 10.516 (“f”) and Nomad-1 at 11.050 (“Vmag”), both of which seemed to be in about the right range. There was a similar range of difference between the two catalogs for “D” (10.890 and 11.500), with Nomad-1’s 11.500 looking like the better choice. I tried a few tricks in order to get Nomad-1 to recognize “C”, but with no luck, so the only values I had were the UCAC4 “f” magnitude of 12.064 and the combined “J” and “K” infrared values, which worked out to a visual magnitude of 12.386.
I had sent this research off to Bill Hartkopf at the same time I sent my findings on HJ 5529, and after some further research, Bill changed the magnitude values for “C”, “D”, and “F” to the numbers shown above in red for the Bu 172 data above.
Apart from the AB pair, the proper motions of the various components of Bu 172 appear to indicate none of them are related physically, especially in the case of “D” (source):
The WDS notes file for Bu 172 describes AB,C as physical, but from looking at the plot above, that doesn’t appear to be the case, although there may well be more involved than I’m aware of.
The binary AB pair, which at a separation of 0.46” was beyond my reach, was discovered in 1875 by Burnham with the combination of his eagle-eyes and six inch f/15 Clark refractor. More than likely he detected an elongation rather than a separation (he sent his observation off to Ercole Dembowski for measurement), but even at that, I would love to duplicate his feat – if I could only persuade the seeing to cooperate! Surprisingly, when Dembowski measured it he came up with the same separation as the WDS Ephemerides shows for 2014, which is a remarkable coincidence. That star has been measured many times, which is evident from Burnham’s list at the right, and the orbital data for it is well established.
The WDS shows the first observation of the AF pair, STU 14, was made in 1893. which may be an indication of a measure made by Burnham, although I can’t find any reference to that star in his catalogs. The three letter identifier refers to K. M. Sturdy, who published in the Webb Society Double Star Circulars in the 1990’s.
That’s it for an interesting and unpredictable look at starlight flowing from der Wasserman’s water jar. You shouldn’t have to read between the lines too much in order to grasp the message underlying the observations of the last two stars: it’s still quite possible for amateur astronomers to contribute in very significant ways to double star research. Remarkable as it may seem, even in the early 21st century you can still point a telescope into the sky and find yourself looking at a sprinkling of stars that don’t quite match the published data. When that happens, it’s well worth the time to do a bit more research and report what you find. You really can make a difference.
Many thanks to many people for help on this one: First to Peter Morris of England for pointing me toward Bu 172, and second to Bill Hartkopf and Brian Mason at the USNO/WDS for help and suggestions on Bu 1515, Bu 172, and HJ 5529. Thanks also to an internationally flavored group of persistent double star hunters and accomplices who also keep a sharp eye out for magnitude discrepancies: Chris Thuemen (Canada), Dr. Wilfried Knapp (Austria), Steve Smith (Colorado), and Steve McGaughey (Hawaii).
Clear Skies! 😎