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Astr110 Photography Projects, Spring 2008

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Sombrero Galaxy, M104 (NGC 4594), Kim VandenAkker

Sombrero Galaxy

The Sombrero Galaxy, which gets its name from its obvious sombrero-like appearance, was discovered in 1781 by Pierre Mechain. At a distance of about 50 million light-years from Earth, it is the most prominent member of a small group of galaxies called the M104 group or NGC 4594 group. The Sombrero Galaxy is a spiral galaxy of the type Sa-Sb; it has both a large bright core and clearly-defined spiral arms. Its bulge is particularly pronounced, and it features a system of several hundred globular clusters. The Sombrero Galaxy lies just beyond the limit of naked-eye visibility, with a magnitude of 8 and a distance of 50,000 light-years across. In terms of size, it is equivalent to roughly 800 billion suns.

In the image above, the major components of a spiral galaxy are clearly visible--there is a large, bright bulge in the center which is surrounded by a flat spiral disk (it is difficult to see the actual spiral in this image since it is an edge-on view). The Sombrero Galaxy has an angular size of about 6 arc min. Using the values of 50 million light-years and 6 arc min for distance and angular size, respectively, the linear size can be calculated to be about 85,000 light-years.

Frommert, Hartmut and Kronberg, Christine. "Galaxies." Students for the Exploration and Development of Space. <http://seds.lpl.arizona.edu/MESSIER/galaxy.html>.

Frommert, Hartmut and Kronberg, Christine. "Messier 104." Students for the Exploration and Development of Space. <http://www.seds.org/MESSIER/m/m104.html>.

"Heritage Project Celebrates Five Years of Harvesting the Best Images from Hubble Space Telescope." Hubble Site News Center. 2 Oct 2003. <http://hubblesite.org/newscenter/archive/releases/2003/28/image/a>.


Right Ascension (J2000) 12:40:00
Declination (J2000) -11:37:00
Filters used Blue (B), Green (V), Red (R), and Clear (C)
Exposure time per filter 5x60 seconds in all filters
Date observed

March 16, 2009 at 6:23:41 EDT