AstroPhotography by Dan Richey

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Andromeda Galaxy
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Andromeda Galaxy

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The Andromeda Galaxy is a spiral galaxy approximately 2.5 million light-years from Earth in the constellation Andromeda. It is also known as Messier 31, M31, or NGC 224, and is often referred to as the Great Andromeda Nebula. Andromeda is the nearest spiral galaxy to the Milky Way, but not the closest galaxy overall. It gets its name from the area of the sky in which it appears, the Andromeda constellation, which was named after the mythological princess Andromeda. Andromeda is the largest galaxy of the Local Group, which consists of the Andromeda Galaxy, the Milky Way, the Triangulum Galaxy, and about 30 other smaller galaxies. Although the largest, Andromeda may not be the most massive, as recent findings suggest that the Milky Way contains more dark matter and may be the most massive in the grouping. The 2006 observations by the Spitzer Space Telescope revealed that M31 contains one trillion stars: at least twice more than the number of stars in our own galaxy, which is estimated to be 200–400 billion. Like the Milky Way, the Andromeda Galaxy has satellite galaxies, consisting of 14 known dwarf galaxies. The best known and most readily observed satellite galaxies are M32 and M110. Based on current evidence, it appears that M32 underwent a close encounter with M31 (Andromeda) in the past. M32 may once have been a larger galaxy that had its stellar disk removed by M31, and underwent a sharp increase of star formation in the core region, which lasted until the relatively recent past. M110 also appears to be interacting with M31, and astronomers have found a stream of metal-rich stars in the halo of M31 that appears to have been stripped from these satellite galaxies. M110 does contain a dusty lane, which may indicate recent or ongoing star formation.

Object Information

Name Andromeda Galaxy
Type Spiral Galaxy
Constellation Andromeda
Catalogue M31 / M110 / M32

Acquisition / Processing

Exposure L - 18 x 300 sec Bin 1
Total 1.5 Hrs
Telescope AP 160 @ f7.7
Camera SBIG STL-11
Camera Temp -22ºC
Guiding SBIG Internal
Mount AP 900GTO
Filters Astrodon-Gen 1 LRGB
Processing CCDStack / PS CS3
Location San Pedro Creek, NM
Date November 26, 2011

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