Andromeda Galaxy

Andromeda Galaxy

I chose this galaxy because of its close proximity to the Milky Way.
Chemicals: elements, metals, above Helium

Location: RA 0° 42' 44" | Dec 41° 16.152'
Stellar Classification: spiral galaxy

The Andromeda Galaxy, also known as Messier 31, M31, or NGC 224, is a spiral galaxy approximately 780 kiloparsecs (2.5 million light-years) from Earth. It is the nearest major galaxy to the Milky Way with the coordinates RA 0° 42' 44" | Dec 41° 16.152'. It received its name from the area of the sky in which it appears, the constellation of Andromeda, which was named after the mythological princess Andromeda. Being approximately 220,000 light years across, it is the largest galaxy of the Local Group with the most dark matter.

Based on its appearance in visible light, the Andromeda Galaxy is classified as an SA(s)b galaxy in the de Vaucouleurs–Sandage extended classification system of spiral galaxies. However, data from the 2MASS survey showed that the bulge of M31 has a box-like appearance, which implies that the galaxy is actually a barred spiral galaxy like the Milky Way, with the Andromeda Galaxy's bar viewed almost directly along its long axis.

Spiral galaxies are organized into three regions: a central bulge, a flattened disk outside the bulge, and the outermost region, the halo. Spiral galaxies are classified in a range of shapes from elliptical to dwarf irregular classes in the Hubble sequence. Bulges and halos are spheroidal in shape. Bulges have a greater central density, thinning quickly, they are more sharply truncated at the outer edges, and have a higher abundance of heavy elements (metallicity). Typically, discs form stars at a steady rate over their lifetime. By contrast, the current data suggests that halo stars are formed early in the history of the galaxy or were acquired when satellite galaxies are absorbed when they collide. Larger spiral galaxies such as Andromeda may have been formed by the merger of other less massive galaxies and their halos composed of the accumulated debris of these smaller galaxies.

Sources:
Wikipedia, the free encyclopedia. (2015, September 9). Andromeda Galaxy. Retrieved September 20, 2015, from https://en.wikipedia.org/wiki/Andromeda_Galaxy

 Andromeda Galaxy. (2013, October 19). Retrieved September 20, 2015, from http://en.citizendium.org/wiki/Andromeda_Galaxy 

 Visible Spectra of the Elements. (n.d.). Retrieved September 28, 2015, from http://www.umop.net/spctelem.htm