Ninety-five Herculis is one of those stars I’ve frequently come across in my reading but had never looked at, despite the numbers of times I’ve made a mental a note to do that. My memory machinery finally functioned at high speed one evening, prompting me to take a look — and when I did, I was also rewarded with a spectacular stellar gem in the form OΣ 341, also known as STT 341.
95 Herculis (Σ 2264) HIP: 88267 SAO: 85648
RA: 18h 01.5m Dec: +21° 36′
Mag: 4.9, 5.2 Sep: 6.3″ PA: 257° (WDS 2010)
Distance: 470 Light Years
Spectral Classification: A5, G8
The easiest way to get to 95 Herculis is to follow the directions on the first chart above, which has you starting at Delta (δ), a beautiful multiple star well worth spending some time with, and following the line of stars that lead east from it to Omicron (ο). When you reach that point, turn to the south and continue about seven degrees, which is about one and a half fields of view in most 8×50 finders. The next chart (below) gives you a close up view of the area you’re headed towards, and shows 95 Herculis in relation to its neighbors — 98, 102, 101, and 96.
In my 76mm Tasco refractor at 48x, 95 Herculis is two sharply defined bright white dots of light which are just touching one another. At 133x, they separate very well, and I noticed that the western component is just slightly smaller than the other one. They both appeared to me to be primarily white with just a tinge of yellow on closer examination. Haas describes them as “pure gold,” and Admiral Smyth saw — I hope you’re sitting down when you read this — “light apple green” and “cherry red.” Obviously, none of these color descriptions are close to each other, so I’ll look again — but without colored lenses in my eyepieces, I really don’t expect I’ll see apple green or cherry red.
These are huge stars. The “A” component is 6.8 times the diameter of our sun and is 167 times more luminous; the “B” component, the larger of the two, has a diameter 19.4 times that of the sun and is 194 times more luminous. But since this pair of stars is a distant 470 light years from us, you won’t need sun glasses of filters! (Data from Jim Kaler’s web site)
The following night I took another look with two larger refractors, a four and a five inch. At low magnification, 55x in the four inch and 59x in the five inch, they were cleanly split, but still very close. The two glowing white globes really stand out against the background of a black sky.
OΣ 341 (STT 341) HIP: 88637 SAO: 85723
RA: 18h 05.8m Dec: +21° 27′
Mag – AB-C: 7.6, 9.8 Sep: 27.8″ PA: 175°
Mag – AE: 7.3, 10.3 Sep: 66.1″ PA: 38°
Mag – AF: 7.4, 11.0 Sep: 112″ PA: 356°
Mag – AG: 7.4, 7.6 Sep: 133″ PA: 239°
Distance: 123 Light Years
Spectral Classification: M1 (for AB)
If you go back to the second chart above, you’ll see our next star lies about half a degree to the east of 95 Herculis. It’s very obvious in a finder, and depending on what eyepiece you’re using on 95 Herculis, you may see this one over at the eastern edge of the field.
This is a beautiful multiple system of five stars. There are also a few stars of similar brightnesses near it that almost look like they belong to this system, but they just happen to be in the vicinity. This system is best seen with three inches or more of aperture, although having located them in the four and five inch refractors, all of the faint components were visible in the 76mm with averted vision at 60x — any more magnification than that tended to increase the glare from the primary and make them harder to see.
In the four inch at 55x the system almost looks like a very small cluster, as was the case in the five inch at 59x. Increasing the magnification in the four inch to 88x didn’t result in a major change in appearance, but it did put some distance between the “C” and “E” components and the primary. Surprisingly, even though it’s only an inch greater in aperture, the image was noticeably brighter at 59x. The four inch is an APO, the five inch an achro, and I much preferred the image in the five — which just confirms my opinion that achros deserve a lot more respect than they get!
The three faint components are grouped closely around the primary in a kind of arc, while the “G” component is off all by itself to the south, although there is a tenth or eleventh magnitude star just to it’s southwest which looks like it’s part of the system, but isn’t. Normally, in a multiple system, the second brightest star follows in alphabetical order, which in this case would be the letter “C,” so I’m not sure what caused it to be designated “G.” Both “AB” and “G” appeared white to me, and of course the others were just too faint for detecting color. Haas again saw color where I didn’t — she describes the primary as “peach white.”
These observations were made under dark skies on July 6th and 7th, 2010, at about 0100.