Blown by the wind from a massive star, this interstellar apparition has a surprisingly familiar shape . Cataloged as NGC 7635, it is also known simply as The Bubble Nebula . This colorful telescopic image includes a long exposure through a hydrogen alpha filter to reveal details of the cosmic bubble and its environment . Although it looks delicate, the 10 light-year diameter bubble offers evidence of violent processes at work. Above and right of the Bubble's center is a hot, O-type star , several 100,000 times more luminous and approximately 45 times more massive than the Sun. A fierce stellar wind and intense radiation from that star has blasted out the structure of glowing gas against denser material in a surrounding molecular cloud . The intriguing Bubble Nebula lies a mere 11,000 light-years away toward the boastful constellation Cassiopeia.
Editor's Note (Jan. 26, 2009): Thanks to Daniel Majaess (St. Mary's Univ., Halifax) for corrections.