I took advantage of few hours of clear sky (with intermittent clouds) during the moonless night of the 27th December 2022 to capture the data of this image. I would have liked to record at least the double of this data, but, given the constantly cloudy weather since one month, I closed the image with what I had.
The image contains the Sh2 objects described below and the planetary nebula PN 173+03.1, visible just in the middle of Sh2-232.
The following info is mostly excerpted from the great site galaxymap.org, that I recommend for the rich and systematic data presented, not to mention its high quality galactic maps.
Sh2-231 to Sh 2-235Sh2-231 to Sh 2-235 form a complex of HII regions located together in the Perseus arm in the outer galaxy. This complex may be associated with an old (330 thousand years) supernova remnant, FVW 172.8+1.5.
There is a giant molecular cloud, G174+2.5, containing Sh 2-231, Sh 2-232, Sh 2-233, and Sh 2-235 that is at a distance of about 1800 pc (5800 ly).
Sh2-232Galactic Coordinates: (173.47°, 3.23°)
This peculiar belted nebula is ionised by two giant stars: the O9.5 III HD 37737 and an anonymous B0 II class star according to Avedisova.
HD 37737 may be a runaway star and is a close binary with a period of 7.84 days.
Sh2-235Galactic Coordinates: (173.61°, 2.8°)
This kidney-shaped HII region is the intersection point of two massive giant molecular clouds (100 thousand and 300 thousand solar masses respectively) with intense star formation. Infrared analysis using the Spitzer space telescope has found 86 young stellar objects within Sh 2-235.
Sh 2-235 is ionised by the O9.5 V star BD +35 1201. Avedisova places this nebula in star formation region SFR 173.61+2.80 with 54 components, including 7 masers, the smaller HI region BFS 46 and several Herbig-Haro objects.
Sh2-231Galactic Coordinates: (173.37°, 2.55°)
According to Avedisova, this visually faint nebula is ionised by the O9.5V class star LS V +35 24. Avedisova combines Sh 2-231 and Sh 2-233 into a single star formation region, 173.37+2.55, that contains 7 masers and numerous young stellar objects.
PN G173.5+03.2 or PK 173+03.1It is a planetary nebula discovered by Purgathofer in 1980, therefore also denominated Pu2 after his name. I could not find any distance estimate.
Picture 1: an overview of Sh2 objects in Auriga, from galaxymap.org. North is approximately in line with the top right corner of the picture.
Just for orientation: Sh2-232 is presented here, Sh2-236 is the Tadpole Nebula, Sh2-229 is the Flaming Star Nebula and Sh2-224 is the Sampan Hat Nebula
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