Astr110 Photography Projects, Spring 2005

Sombrero Galaxy, Ruth Lobbestael

This bright spiral galaxy is located in the constellation Virgo. It was discovered by Pierre Méchain in 1781. It is located 50,000,000 light years away, with a magnitude of 8.0. This galaxy was the first one with a large redshift found. This was discovered by Vesto M. Slipher, who also was the first to detect the galaxy's rotation, and did so at Lowell Observatory in 1912. Its redshift has been discovered to correspond to a recession velocity of about 1,000 km/sec. This galaxy appears so unique because of the dust that forms the ring around the galaxy and blocks light from reaching us from that area of the galaxy.

The Sombrero Galaxy has an apparent angular size of 9 arc minutes by 4 arc minutes. Its linear length is 13,890 light years. There are several different types of spiral galaxies that are classified separately. Spiral galaxies, "normal" and barred, with conspicuous bulges (especially near their center) are classified "Sa" or "SBa", while those that have prominent bulges and pronounced arms are classified "Sb" or "SBb", and those which are dominated by the arms are "Sc" or "SBc". The Sombrero Galaxy is categorized as Sa-Sb, with both a big bright core, as is present above, as well as spiral arms which are visible during shorter exposures. Another well-known example of a spiral galaxy is the Milky Way.

References:

Messier Object Index:
http://www.seds.org/messier/m/m104.html
http://www.seds.org/messier/spir.html

European Southern Observatory:
http://www.eso.org/outreach/press-rel/pr-2000/phot-07-00.html