M52 is an open star cluster of about 200 stars that is 3,000 to 7,000 light-years away. This image is a detail taken from the image below, which shows M52 and the Bubble Nebula.
M52 is in the upper left. The Bubble Nebula (lower right) is a roughly spherical shell of gas created by the stellar wind from a young, hot, massive, central star. It is embedded in a molecular cloud that emits visible light after absorbing UV from the same central star. It is 7,000 to 11,000 light-years away and is cataloged as NGC 7635. A detail of the Bubble Nebula is here.
Astro-Physics 155mm refractor at f5.4. 216 minutes L and 368 minutes RGB on 2011-12-18 and 2011-12-24 plus 256 minutes through an Astrodon 3 nm H-a filter on 2011-11-08 using a QSI 583 from northern New Jersey. North is up. ©2011