Amazing Sombrero Galaxy

It resembles a shining UFO or a wide-brimmed hat, but this isn't what it looks like.One of most famous spiral galaxies (Messier 104) is also widely known as the "Sombrero" (the Mexican hat) because of its particular shape. The galaxy's impressive, unusually large and extended central bulge and its lane of dark interstellar dust give the galaxy its unusual resemblance.

This spectacular and massive object, 50,000 light years across, is located at a distance of about 30 million light-years. For comparison, in size, this impressive galaxy is equal to 800 billion suns and it can be viewed from Earth, from just 6 degrees south of its equatorial plane.

In the 19th century, some astronomers speculated that M104 was simply an edge-on disk of luminous gas surrounding a young star, which is prototypical of the genesis of our solar system.

Discovered by Pierre Méchain in 1781, M104 is considered to be the first galaxy for which a large redshift (equivalent to a recession velocity of approximately 1,000 km/s) was discovered, by an American astronomer Vesto Slipher in 1912.

Astronomer V. M. Slipher also discovered that the object appeared to be rushing away from us at 700 miles per second.

This enormous velocity offered some of the earliest clues that the hat-like object was really another galaxy, and that the universe was expanding in all directions.

Like the Andromeda Galaxy, M104, has a rapid rotation in its center. The object has a very extended faint halo and a mildly active nucleus indicating the presence a central supermassive black hole, which may be even more massive than the one believed to be in the nucleus of the Andromeda Galaxy.

Sombrero Galaxy can be found towards the constellation Virgo, which is joined by many other galaxies in a complex, filament-like cloud that extends to the south of the Virgo Cluster.

The Chandra X-ray image (in blue) shows hot gas in the galaxy and point sources that are a mixture of objects within the Sombrero as well as quasars in the background. The Chandra observations show that diffuse X-ray emission extends over 60,000 light years from the center of the Sombrero.
The Hubble optical image (green) shows a bulge of starlight partially blocked by a rim of dust, as this spiral galaxy is being observed edge on. That same rim of dust appears bright in Spitzer's infrared image, which also reveals that Sombrero's central bulge of stars.

Approximately 1500 individual galaxies make up the cluster, which represents the physical centre of our Local Supercluster.

Its enormous mass leads to a gravitational attraction that slows the velocities of all the galaxies around it, causing matter to effectively move towards it in what is known as a ‘Virgo-centric flow’.

We are not at a sufficient distance to escape this pull and so, one day, our Local Group will stop receding from Virgo and instead begin to fall and eventually merge into the cluster.

One of the most popular sights in the universe - Messier 104

This is a very beautiful compiled image of the Sombrero Galaxy hovering in space. The Spitzer picture is composed of four images taken at 3.6 (blue), 4.5 (green), 5.8 (orange), and 8.0 (red) microns.

The contribution from starlight (measured at 3.6 microns) has been subtracted from the 5.8 and 8-micron images to enhance the visibility of the dust features. In Spitzer's striking infrared view, the galaxy looks more like a "bull's eye."

What's going on in the center of this spiral galaxy? Billions of old stars cause the diffuse glow of the extended central bulge. Close inspection of the bulge in the above photograph shows many points of light that are actually globular clusters similar to those found in our own Galaxy.

Astronomers estimate that there are nearly 2,000 such clusters — 10 times as many as orbit our Milky Way galaxy. The ages of the clusters are similar to the clusters in the Milky Way, ranging from 10-13 billion years old. M104's spectacular dust rings harbor many younger and brighter stars, and show intricate details astronomers don't yet fully understand.

The Sombrero Galaxy from Hubble. Credit: NASA, ESA, and the Hubble Heritage Team (STScI / AURA)

The radio properties of Messier 104 are unusual for a spiral galaxy, namely, it has a variable core. The optical spectrum of the central region displays emission lines from hot gas. This points to Messier 104 harbouring a weak Active Galactic Nucleus (AGN).

Although more commonly known from the much more luminous and distant quasars and powerful radio galaxies, the weak AGN in this galaxy lies at the opposite extreme. The most likely explanation, based on X-ray emission, suggests that there is material falling into the compact core, where a 1-billion-solar-mass black hole resides - being a large, central black hole accreting circumnuclear matter at a slow pace.

Fifty million-year-old light from the Sombrero Galaxy can be seen with a small telescope towards the constellation of Virgo. At a relatively bright magnitude of +8, Sombrero Galaxy is just beyond the limit of naked-eye visibility but it is easily seen through small telescopes.