With Cygnus clearing the trees to the East, I figured it was time to try the AT92 with my L-eXtreme filter for the first time, and go after some emission nebulae. Propeller has been on my list for a while, and it seemed to fit my new FL nicely. I resisted the urge to additional time to this target, as I wanted to see the result with a more modest amount of integration time so I could plan for future HaOIII targets.
Simeis 57 (also designated individually as
DWB 119 for the northern "blade" and
DWB 111 for the southern) is an area of low-density emission nebulosity just off Sadr in Cygnus, forming a distinctive propeller shape. There is some OIII in the area, particularly concentrated in one region just east of the main body. Its shape suggests that it might be a rotating outflow but there is no observable central source for this dynamic, and it's likely just coincidence that it has this shape.
The most likely candidate for excitation is the Wolf-Reyet star
WR140, which is so distant from Simeis 57 that it is out of the frame of this image. WR140 was recently
imaged by JWST and found to have a spectacular series of shells, like rings of a tree, generated by the interaction between WR140 and its binary partner, an even brighter Type-O star.
REFERENCE:L. H. T. Oudshoorn, F. P. Israel, J. Brinchmann, M. B. C. Kloppenburg, A. G. A. Brown, J. Bally, T. R. Gull, and P. T. Boyd. (2021). The peculiar nebula Simeis 57: II. Distance, nature and excitation. A&A650, A171.
https://doi.org/10.1051/0004-6361/202039372
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