Situated halfway between bright orange Betelgeuse and blue-white Bellatrix and about three degrees to the north, Meissa is a busy little devil. It anchors a large open cluster, Collinder 69, and illuminates a large ring of gas 150 light years in diameter. Meissa “A” is a very hot star sporting a sizzling temperature measured at 35,000 Kelvin, and Meissa “B” is just barely cooler at 27,000 Kelvin. At those temperatures, they each send a tremendous amount of energy into that cloud of gas. “A” radiates 65,000 times more than the sun and “B” drops down to a comparatively smaller, but still considerable, 5500 times more than our own star. The source of the name is somewhat vague, but James Kaler’s best guess is it’s from the Arabic for “the Proudly Marching One.”
In a telescope, Meissa and the surrounding area is a beautiful sight at any time, but especially for my photon deprived eyes after a lengthy run of rotten viewing weather. South of Meissa are two fourth magnitude stars, Phi-1 (Φ-1) and Phi-2 (Φ-2). This pair combines with Meissa to form a slightly tilted irregular triangle. Phi-1 is a class B0 star located at a distance of 985 light years, and Phi-2, which to my eyes has a very distinctive reddish-orange flavor to it, is a G8 star at a much closer 116 light years. Inside that triangle is a line of three north-south aligned stars. The northernmost has a magnitude of 7.6, and the next one to the south is at 7.5. The southernmost one, HIP 26212, is a class B2 star with a magnitude of 6.7 sitting way out there at the sizable distance of 1388 light years. Burnham comments that the moon would actually fit within this triangle, which measures twenty-seven arc minutes on the west side and thirty-three along the south edge. Completing the telescopic scene is OΣ 111 (STT 111), sitting about 14 arcminutes north of Meissa. This one is another double, with magnitudes of 5.6 and 9.7 separated by 2.9″, positioned at a distance of 1463 light years from us.
So as should be rather obvious from this long introduction, pleasing photonic opportunities abound in this very small area. And as I alluded to earlier, my opportunities have been severely curtailed for the past five weeks due to a parade of very wet clouds that were considerate enough to drop thirty-three inches of rain on my observing sight as they passed through. I tried several times to get a peek at Meissa through sucker holes, but as usual, the clouds waited until I was lined up and then leaped back across my view. I even managed to get rained on twice during those futile frustrating attempts. So pull up a chair and make yourself comfortable, because we’re going to spend some time here — no looking and leaving, no viewing and vamoosing — we’re going to sit and stay! My goal is to become so familiar with this wonderful area of sky that I can call up an image of it in my memory quicker than you can swap browser screens.
Finding this area is easy – as described above, from a point midway between Betelgeuse and Bellatrix, move north a few degrees. If you have reasonably dark skies, you’ll see a faint triangle of three stars just north of that line, which represents the head of Orion. Moving from east to west and then north, these stars are Phi-1, Phi-2, and Meissa. In a finder with a four or five degree field of view, this entire area — from the Phi twins up to OΣ 111 — is a an eye-catching open cluster known as Collinder 69, and it’s especially attractive due to the three north-south aligned stars between Phi-1 and Meissa. I dropped a 26mm Plossl (30x) into the focuser of my AT-111, which gave me a reasonably wide 1.7 degree field of view —— and I could feel all the rusty corroded connections in the dim recesses of my astronomical memory coming to life once again as the photons flew through them! What a sight for star starved eyes! The Stellarium screen image below gives you a hint of what it’s like, but don’t take my word for it — go out and take a look!
So, on to the serious stuff — Star Splitting!!!
Meissa (Lambda [λ] Orionis) (Σ 738) (AB is H II 9) HIP: 26207 SAO: 112921
RA: 5h 35.1m Dec: +09° 56′
Magnitudes A: 3.5 B: 5.5 C: 10.7 D: 9.6 E: 9.2
Separation AB: 4.2″ AC: 28.7″ AD: 78.0″ AE: 150.4″
PA AB: 44° (WDS 2011) AC: 185° AD: 272° AE: 279° (C, D, & E all WDS 2008)
Distance: 1056 Light Years
Spectral Classification A: O8 B: BO.5
Now Meissa “B” is not particularly difficult to see, so I started with a 14mm Radian (56x) in the AT 111 and was just able to glimpse it clinging to the side of the primary, and about an arc minute off to the west, “D” was also easy to pick out of the glare, and “E” is easy to see hovering all by itself out beyond “D”. Out with the 14mm and in with a 12mm version (65x) and “B” became a perfectly round white dot of light just out of hugging range of “A,” and “C” now came into view with averted vision. I’m not in a hurry here ;), so the next move was to a 10mm Radian (78x) which gave me a slightly larger, but essentially similar view. Still savoring the moment, I reached for the 8mm Radian (97x) — which allowed me to pick out “C” with direct vision, although it was difficult to hold for long. One more magnified leap forward, to a 6mm Radian (130x), and I was able to hold “C” with direct vision for long periods of time. Searching for an aesthetic alternative, I dropped back to a 7.5mm Tak LE (104x) and was surprised at how steady “C” was in it. And then, backing away from my focus on the four Meissa components, I went back to the 14mm Radian and took in the entire field of view once more. As I sat there for several minutes absorbing the beauty of it, I noticed “C” was occasionally visible out of the corner of my eye.
Two nights later I returned with a Tasco 60mm f/16.7 for another look, mainly curious about the different perspective provided by the smaller aperture and the longer focal length. With a 26mm Plössl (39x) I needed averted vision to pick out “D,” but was able to see it with direct vision when I moved up to a 20mm Plössl (50x) — and “E” was obvious, thanks to it’s greater distance from all the glowing that was going on closer in. With 15mm (67x) and 11mm Plössls (91x) I was able to glimpse “C,” but it was difficult because of the cloud of gas which is illuminated by Meissa “A.”
There was something noticeably different about this view, though. Of course, it wasn’t as bright and the stars were slightly dimmer in comparison to the four inch aperture of the scope I used two nights earlier, but those weren’t surprises. Instead, it was the compactness of the view that intrigued me. The field of view in the AT111 using the 14mm Radian comes in at 1.06 degrees, while the 20mm Plössl in the Tasco gave me .98 degrees — so, from a numbers standpoint, they’re essentially the same. But the entire field in the Tasco was just “neater,” as in “freshly pressed” (with a stellar iron) — which I’m pretty sure was just a result of the smaller image scale resulting from the smaller aperture. That’s not to say the view in the AT111 was lacking in any way — just that it was not the same. Everyone has their preferences, and those will change over time. On that night, I preferred the view in the 60mm. Next week — if it’s clear (!) — I may lean back to the AT111.
Now about that gas cloud that Meissa illuminates with so much energy: I can’t honestly say I’ve ever noticed it prior to these two nights, but it really was not difficult to see in either the 111mm or the 60mm refractor. If you look right at Meissa “A,” you won’t see it — but if you avert your vision just a bit, it pops right into view. I could see it quite easily at both low and high magnifications that way. Most of the time it had an oval shape, extending about an arc minute to the east of “A” and as far west as “D.” And I noticed in an 8×50 finder it appears slightly larger than that.
OΣ 111 (STT 111) HIP: 26215 SAO: 94671
RA: 5h 35.2m Dec: +10° 14′
Magnitudes: 5.6, 9.7
Position Angle: 351° (WDS 2003)
Spectral Classification: B9
Distance: 1463 Light Years
Up to this point, I’ve neglected poor old OΣ 111, which sits on the north fringe of this cluster of stars. Looking at the statistics, I could see this was going to be a difficult one to split, but based on experience, it certainly didn’t strike me as being out of range. Both nights I was out, the seeing was below average — well below on the first night with the AT111, just on the negative side of average on the second night when I tried with an AR-5. On that first night of no luck, I stopped with a 5mm Tak LE (155x) because the image was bouncing around so badly I couldn’t hold it in view for more than a fraction of a second. I was sure I could nail it, though, the next time out with the five inch AR-5. Again, no luck, and again, I had to give up because the image was bouncing around so badly I would have needed half a dozen motion sickness pills to keep at it. I may have had a glimpse of it with the 5mm Tak (236x), but it was so fleeting it was impossible to be sure. I gave a 4mm Plössl (295x) a try, but it bounced out of the field of view more than it was in it.
I’ll come back to this one on a night when the seeing is better. I suspect what I’ll find is the companion is a very small pinpoint of light. If you, the reader, happen to split this elusive little devil, by all means post a comment here and let us know. We would be honored to have it on this site.
These observations were made on the evenings of two different years: December 30th, 2010, and Jan 1st, 2011. 🙂 Data on Meissa is from Jim Kaler’s web site, which is highly recommended!