The bubble nebula NGC 7635
"At the heart of the Bubble Nebula is a star that is forty times more massive than our Sun. Located in the northern constellation of Cassiopeia, this spherical nebula requires a large telescope, dark skies and contrast enhancing filters before it can be seen visually due to its low surface brightness.The bubble, itself, is actually quite large- spanning six light years across and it’s expanding at about four million miles per hour! The bubble was formed by the bright star that is positioned below and to the right of its center. The radiation released from inside that star is so intense that it literally blows its outer surface off into space. The bubble marks the leading edge of the gust from these powerful stellar winds as it plows into denser surrounding material. This scene is approximately 7,100 light years from Earth." by R. Jay Gabany on August 9, 2006
