Friday, July 7, 2017

The Sombrero Galaxy...


Also known as Messier Object 104 (M104) or New General Catalogue 4594 (NGC 4594), it is an unbarred spiral galaxy in the constellation Virgo located about 31 million light-years from Earth.

The Sombrero Galaxy was discovered on May 11, 1781 by Pierre M├ęchain.

The galaxy is approximately 50,000 light-years across, which makes it just a third of the size of the Milky Way.

Its nucleus is both unusually bright and large, and surrounded by a vast halo. Astronomers initially thought that the halo was small and light, later observations by the Spitzer Space Telescope showed that the halo was both larger and more massive than previously thought.

The core is surrounded by a prominent ring of cold atomic hydrogen gas, cold molecular gas, and dust. A particularly dark lane of dust lane exists at the outer edge of the ring, marking the center.

The nucleus of the Sombrero Galaxy is probably devoid of any significant star formation activity. Yet, it is a powerful and steady source of synchrotron emissions. Synchrotron emission occurs when high-velocity electrons oscillate as they pass through regions with strong magnetic fields. This emission is quite common for galactic nuclei with high star formation. The nucleus is also a powerful emitter of submillimeter radiation.

In the 1990s, astronomers discovered that the galaxy has a super-massive black hole at its center, one approximately 1 billion times the mass of the Sun. But neither the synchrotron emission nor the submillimeter radiation appear to be connected to the black hole.

No one knows what's going on in there...

The ring of the Sombrero Galaxy appears to be quite an active region for star formation. The galaxy also appears to have a rather high number of globular clusters, spherical collection of stars that orbit the galactic core much as a satellite does.

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