Sh2-182 and the Interstellar Shell GSH 122+02-77

Tucked away in Cassiopeia around 12,000 light years away lies the small HII region designated as Sh2-182. But it’s not at all the star of this show. That billing goes to the blue filamentary region catalogued as GSH 122+02-77 (GSH stands for Galactic Supershell).

This not-often-photographed area popped up on my radar when I was searching the sky surveys for Sharpless objects I had yet to capture. As I researched it, I could only find two other good images of it—both on Astrobin, and both of them outstanding efforts. The first one I found was taken by my friend, Göran Nilsson. The second by my friend, Markus Horn.

Following the trails they left behind, it turns out that the incomparable Marcel Drechsler identified GSH 122+02-77 in the Simbad database classified as an “Interstellar Shell.”

Göran has speculated that the super-hot star WR1 located nearby may have something to do with this filamentary formation. That sounds very plausible to me. In general, the origin and nature of galactic supershells is not known and continues to be an area of study. But one theory is that they form through gaseous “collision with high velocity clouds” created by nearby large, hot stars. So Göran may have it right.

In any case, all this was a very pleasant surprise to me. I was taking a wide-angle shot of the region containing Sh2-182 and several other Sharpless objects when all this appeared. After attempting to process the entire frame, I realized that the various objects in the image required different treatments because of their diverse compositions and nature, so I split them apart and handled them separately. This is the first of those treatments. While these efforts are not the best possible images one could take of these objects with a bigger aperture and a longer focal length, I continue to be astounded by the detail that emerges from the FSQ at a focal length of only 382mm.