M31 The Andromeda Galaxy



M31 and M32 in the Constellation of Andromeda

Took my first astro-photo of an object outside the Milkyway. The night I took this was a bit cloudy and this image is the combination of only four light frames (4x20 secs). Consquently, I am quite pleased that I was able to tease out some detail of the galaxy core showing hints of the spiral arms and dust lanes.
You can also see the gravitationly linked elliptical galaxy M 32 which is part of the Andromeda Group our nearest galactic neighbours.

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 (10¹²) stars, at least twice more than the number of stars in our own galaxy, which is estimated to be c. 200–400 billion.

Andromeda is estimated to be 7.1×10¹¹ solar masses. In comparison a 2009 study estimated that the Milky Way and Andromeda are about equal in mass,^] while a 2006 study put the mass of the Milky Way at ~80% of the mass of Andromeda. The Andromeda Galaxy and the Milky Way are expected to collide in perhaps 4.5 billion years.