This one is hyper classic object – NGC7635 Bubble Nebula in Cassiopeia together with M52 open cluster. This extraordinary HII molecular cloud is placed about 11,000 light years away. The “bubble” shape itself is formed with stellar winds of massive, hot central star of magnitude 8.7mag that is supposed to be 44 times more massive than Sun.
Last few nights at my suburban backyard were not great with transparency, but seeing was pretty decent and quite stable, so I decided to try on this target and reach for some detail in the Bubble. Image below is 8 hours in 10 minutes subframes in Ha band. Shot with QHY163M camera and TS130/910 refractor on immortal EQ6 mount.
Check the color version here.