The Bubble Nebula (NGC 7635 / C11)
NGC 7635 (Caldwell 11), the Bubble Nebula, is an emission nebula in the constellation Cassiopeia located at a distance of approximately 7800 light years. The relatively bright star at about the 11 o'clock position within the prominent bubble is known as BD +60°2522 or SAO 20575 and is the source of the bubble shape. The star is known as a Wolf-Rayet star, which is an O-type star that is nearing supernova stage. These stars blow off significant portions of their mass while in this stage. It has an enormous energy output and a powerful stellar wind which is impacting the molecular cloud surrounding the star. This impact is resulting in the bubble shape clearly seen in this image. The bubble is not centered around the Wolf-Rayet star due to differences in the density of the surrounding gaseous material. The Bubble Nebula is embedded in a surrounding HII region, Sharpless 162 (S162), which is faintly visible throughout the frame of this image. Another feature to look for in the image is the presence of at least one additional bubble. The main bubble can be seen to be contained within another bubble about 2.5 times the diameter of the smaller bubble and extends out to the bright star to the right of center in the image. More information about this object can be found at Wikipedia - Bubble Nebula.
This image is a 204-minute Hydrogen Alpha-filtered image obtained on the evenings of 4 and 6 September combined with 60-minute red, green and blue images from 6 September. The Hygrogen Alpha image was used as the luminance and also blended with the red channel. The image was obtained through a William Optics FLT110 4.3" f/7 refractor with an SXV-H9 CCD camera.
The above image is a full-resolution crop of the bubble region. Below is the hydrogen-alpha monochrome image showing the details in the emission nebula.
Return to AstroImages.org CCD Images