It had been a long while since I last took a stroll through Lacerta, so I had to grab my well-worn copy of Sky and Telescope’s Pocket Sky Atlas and relocate the constellation’s dim outline between Cygnus and Cepheus. Lacerta is not one of those constellations that draws attention, which is unfortunate since the Milky Way runs through about 90% of its stellar real estate – meaning it has more than its share of double stars and open clusters. I was back to check on the Lacertan lizard once again because of a question about the magnitude of one of the components of 8 Lacertae, which in keeping with Lacerta’s rich stellar tradition, also has more than its share of stellar companions. And as long as I was there, I decided to poke around and see what else I could see, which led to a magnitude of additional questions.
Even though it’s the first part of December as I write this, from my forty-five degree latitude Lacerta is almost directly overhead at 7 PM, parked in a holding position between Cygnus, Andromeda, and Pegasus, and Cepheus.
A line drawn from Beta (β) Cephei through Zeta (ζ) Cephei will actually lead you directly to 8 Lacertae:
But because Lacerta is a dim constellation . . . . . .
. . . . . . you might find it easier to aim an 8×50 or 9×50 finder at 4.5 magnitude 6 Lacertae, move northeast a few degrees to 4.5 magnitude 11 Lacertae, and then drop southeast to 5.1 magnitude 13 Lacerate, using 5.0 magnitude 15 Lacertae as a reference point, and then move south to 5.3 magnitude 12 and 4.9 magnitude 10 Lacertae, which form a triangle with sixth magnitude 8 Lacertae parked in the west corner. That way you’ll be sure to land on the right star at least. There should be little chance of confusing 8 Lac with another star since “A”, “B”, and “E” are bright and very obvious:
8 Lacertae (AB is H IV 86) HIP: 111546 SAO: 72509
RA: 22h 35.9m Dec: +39° 38
|STF 2922 AB:||5.66, 6.29||22.40″||185°||2014|
|A 1469 AC:||5.66, 10.38||48.90″||168°||2014|
|A 1469 AD:||5.66, 9.09||81.60″||144°||2014|
|A 1469 AE:||5.66, 7.25||337.80″||239°||2011|
|DAL 28 AG:||5.66, 14.08||78.60″||194°||2012|
|COM 8 BF:||6.29, 10.97||127.60″||175°||2012|
|A 1469 CH:||10.38, 14.60||1.40″||254°||1932|
|A 1469 DI:||9.08, 13.30||10.10″||227°||2012|
|DAL 28 GJ:||14.08, 12.99||6.10″||78°||2009|
Distance: “A” is 2160 Light Years; “E” is 428 LY (Simbad)
Spectral Classifications: “A” and “B” are B2, “D” is A0, “E” is F0
Notes: Mag of I changed from 11.0 to 13.3 as of 10-29-2015
Magnitudes of GJ are reversed in WDS, should be 12.99 and 14.08
In a mid-October email from Mike Hyrczyk via Chris Thuemen, Mike mentioned he had looked at 8 Lacertae and found the “I” component wasn’t visible in his six inch refractor. At the time, it was listed in the WDS at a magnitude of 11.0, normally well within reach of a six inch scope. That evening, I pointed my six inch f/10 refractor at the complex star and, at 152x, confirmed Mike’s observation. I tried higher magnifications – 253x, 365x, and 380x – and may have had a brief glimpse of the fickle star, but there was no doubt it was fainter than the WDS’s 11.0 magnitude. Chris used a 9.25 inch SCT the following night and basically had the same experience, although he may have detected an elongation in the DI pair. Chris also noticed the magnitudes of the GJ pair were reversed in the WDS, which hasn’t been corrected as of this writing.
Given the 10.10” separation listed for the DI pair, experience told me that a magnitude of 13.0 was about the brightest “I” could be, if in fact I had actually seen it with my six inch refractor in the combined AB glare. A check of photometry records in the UCAC4 catalog showed magnitudes of 13.828 (f.mag) and 13.598 (J and K converted to visual), which were too faint for me to have had a glimpse of the star. I sent what information I had to Bill Hartkopf at the USNO/WDS, who consulted additional photometry records, arriving at a magnitude of 13.30 for “I”.
So — after that long introduction, it’s about time we took a look:
There’s also an excellent photo and discussion of the 8 Lacertae complex on page 52 of the November issue of Sky and Telescope. Sue French was unable to see “I” with a 10 inch reflector, but found a fifteen inch scope brought it into view, which supports the WDS magnitude change to 13.30. Sue also noticed the error in the WDS listing for the GJ pair.
His 84° 30’ south preceding works out to a present day figure of 185° 30’, which is a good match with the current WDS figure, but his separation of 17” 14’” puts the AB pair five arc seconds closer than the WDS data. He describes six stars, which probably correspond to the A through F pairs, although his description of their relative magnitudes is difficult to follow. The Latin phrase at the top of his catalog entry translates as “In the middle of the tail”, which seems to indicate a slightly different configuration for Lacerta than what I show above in the first chart.
Sirs John Herschel and James South made two observations of 8 Lacertae in September of 1823, which are shown at the right (source, last title on page). Their measures of AB, which are summarized near the bottom of the page, are in line with the current WDS data, as are their measures of the AD pair (145° 15’, 82.52”, which they refer to as AC). They seem to have entirely missed the closer 10.38 magnitude star now referred to as “C”.
At the bottom of that same page, they refer to an erroneous measure of the AB pair made by Piazzi in 1800 (212° 58’ and 19.072”). Admiral W.H. Smyth also refers to that error on pp. 519-520 of his Bedford Catalog, as well as William Herschel’s 1782 PA error. Relying on his distinctive pre-Victorian vocabulary to make the point, he wrote: “Here the anomalies are palpably owing to error, and the fixity of the objects appears unquestionable.”
The Admiral was irrefutably correct in regard to the “unquestionable fixity” of the objects. Given the 2160 light year distance of “A”, little proper motion is exactly what would be expected. Simbad doesn’t provide a distance for “B”, but it does show “E” to be at 428 light years, which is also far enough away that minimal proper motion would be the norm. I checked the most recent PM data available, which comes from the USNO’s URAT1 catalog, and it confirms the minimal motion for each of the stars:
“E” shows the most motion, which again is to be expected since it’s four times closer to us than “A”. There are no parallaxes available in Simbad on the other components of the system, but judging by their slight motion, they may well be about the same distance as “A”. And at those distance, it’s impossible to come to any conclusion on shared physical motion based on the PM numbers.
Before heading out into the night air to look at 8 Lacertae, I used Sky Tools 3 to take a quick look around the neighborhood for other interesting stars, and quickly found an intriguing multiple star, ROE 47, located just 41’ to the west (here’s our third chart again). So give your scope a careful nudge in that direction and you’ll be greeted by a sixth magnitude star with several faint companions.
ROE 47 HIP: 111259 SAO: 72446
RA: 22h 32.4m Dec: +39° 47’
|ROE 47 AB:||5.90, 11.46||42.90″||155°||2012|
|ROE 47 AC:||5.90, 12.40||33.50″||341°||2012|
|ROE 47 AD:||5.90, 12.20||103.70″||216°||2010|
|FYM 109 AF:||5.90, 14.11||22.00″||106°||2012|
|ROE 47 DE:||12.20, 12.30||6.60″||175°||2012|
Distance: 684 Light Years
Spectral Classification: “A” is A6
Notes: Mag of C changed from 10.2 to 12.4 as of 10-29-2015
Mag of D changed from 11.36 to 12.2 as of 10-29-2015
Mag of E changed from 9.90 to 12.3 as of 10-29-2015
This one had what you might call a magnitude of problems, but before wrestling with that issue, let’s take a look:
It didn’t take but a few seconds to realize that some of the fainter components I was looking at were fainter than the WDS data said they were. As the “C” component flickered in and out of view, I could see it was clearly fainter than the 10.2 magnitude then listed for it in the WDS. There was also something clearly amiss with “D”, which wavered between direct vision and averted vision, meaning it was also fainter than the WDS’s 11.36. And “E”, which was listed at a magnitude of 9.9, was not the conspicuous speck of light it should have been – in fact, it should have been over-powering “D”. After I separated the DE pair at 253x, it was clear they were both about the same magnitude – so 9.90 was nowhere close to being correct. Chris Thuemen also looked at ROE 47 and basically came to similar conclusions.
There’s a huge amount of photometric data available in both the NOMAD-1 and the UCAC4 catalogs, so I turned to both of those to see what I could find. Looking at “C”, I found data pointing to a magnitude of 12.3. In the case of the DE pair, the UCAC4 Vmags, which are normally very dependable in this range, showed 11.358 for both stars, which seemed too bright to me. The UCAC4 f.mag and the J & K visual approximations pointed toward a magnitude of 11.9 to 12.0, which struck me as being closer to what I had seen.
I sent off what I had to Bill Hartkopf at the USNO/WDS, who used additional data to make the changes I’ve listed at the bottom of the ROE 47 data above. Incidentally, Bill is always quick to say he appreciates these observations very much. With the WDS data base approaching something like 130,000 stars, the only way these kinds of errors get corrected is when visual observers note the discrepancies and report them to the WDS.
Digging into the history of ROE 47, it appears the AB and AD pairs were discovered in 1895 by E.D. Roe, Jr., a British amateur astronomer, who used a six inch refractor. He added the “C” and “E” components in 1910, as shown in the excerpt at the right from a 1911 issue of the Astronomische Nachrichten.
I couldn’t find any biographical material on E.D. Roe, but it appears he must have had an astronomically dry sense of humor. If you look at the top left hand corner of the image above, you’ll see he used the Greek symbol “ρ” as an identifier, which in Greek is pronounced rho, as in Roe. Obviously he liked a good laugh.
Next trip – who knows. The winter rains are here and the few clear skies I’ve seen have had more dancing and twinkling stars than an out of control strobe light at an all-night dance party, meaning atrocious seeing, which is not usual for this time of the year. As soon as the weather cooperates (raining hard now with 60mph gusts of wind), I’ll see what I can find to grace the pages of this blog.
Until then, Clear and Cooperative Skies! 😎