The Sombrero Galaxy (also known as Messier Object 104 or NGC 4594) is an unbarred spiral galaxy in the southern edge of the constellation Virgo, located 29 million light-years from Earth. It has a bright nucleus, an unusually large central bulge, equivalent to 800 billion suns, and a prominent dust lane in its inclined disk. The dust lane is composed mainly of dust and hydrogen gas, and is the main site of star formation within the galaxy. The dark dust lane and the bulge give this galaxy the appearance of a sombrero. Astronomers found that the halo around the Sombrero Galaxy is larger and more massive than previously thought, indicative of a giant elliptical galaxy, about 50,000 light-years across. It has an apparent magnitude of +8.98, making it easily visible with amateur telescopes.
Hubble easily resolves M104’s rich system of globular clusters, estimated to be nearly 2,000 in number — 10 times as many as orbit our Milky Way galaxy. Embedded in the bright core of M104 is a smaller disk, which is tilted relative to the large disk. X-ray emission suggests that there is material falling into the compact core, where a 1-billion-solar-mass black hole resides, about 250 times larger than the black hole in the centre of our Milky Way galaxy.
In 1912, astronomer V. M. Slipher discovered that the hat-like object appeared to be rushing away from us at the speed of more than 1,000 kilometres per second. This enormous velocity offered some of the earliest clues that the Sombrero was really another galaxy, and that the universe was expanding in all directions.
Visible and Infrared Images
NASA’s Spitzer and Hubble Space Telescopes joined forces to create this striking composite image of the Galaxy. In Hubble’s visible light image (lower left panel), only the near rim of dust can be clearly seen in silhouette. Recent observations using Spitzer’s infrared array camera (lower right panel) uncovered the bright, smooth ring of dust circling the galaxy, seen in red. Spitzer’s full view shows the disk is warped, which is often the result of a gravitational encounter with another galaxy, and clumpy areas spotted in the far edges of the ring indicate young star-forming regions.
The Hubble Heritage Team took six pictures of the galaxy and then stitched them together to create the final composite image (Visible + Infrared Image) in May-June 2003.