Friday, February 20, 2009
Sombrero Galaxy (M104)
The Sombrero Galaxy (also known as M104 or NGC 4594) is an unbarred spiral galaxy in the constalation Virgo. It has a bright nucleus, an unusually large central bulge, and a prominent dust lane in its inclined disk. The dark dust lane and the bulge give this galaxy the appearance of a sombrero. The galaxy has an apparant brightness of 9.0, making it a galaxy that can easily be seen with amateur telescopes. The large bulge, the central huge black hole, and the dust lane all attract the attention of professional astronomers. As noted above, this galaxy's most striking feature is the dust lane that crosses in front of the bulge of the galaxy. This dust lane is actually a symmetric ring that encloses the bulge of the galaxy. Most of the cold atomic hydrogen gas and the dust lies within this ring. The ring might also contain most of the Sombrero Galaxy's cold molecular gas, although this is an inference based on observations with low resolution and weak detections. Additional observations are needed to confirm that the Sombrero galaxy's molecular gas is constrained to the ring. The Sombrero Galaxy has a relatively large number of globular clusters. Observational comparable to other galaxies with large bulges. These results have been repeatedly used to demonstrate that the number of globular clusters in galaxies is thought to be related to the size of the galaxies' bulges. The surface density of the globular clusters generally follows the light profile of the bulge except for near the center of the galaxy.