A Close Neighbour
Andromeda, the nearest major galaxy to the Milky Way, is shown here in this wide-field optical image from Kitt Peak.
Located in the constellation of Andromeda (the Princess), the Andromeda Galaxy is a large spiral galaxy over 65,000 light years in diameter and approximately 2.9 million light years from Earth.
(Credit: NOAO/AURA/NSF/T.Rector & B.A.Wolpa)
The central region of Andromeda is shown in a composite image, with X-rays from NASA's Chandra X-ray Observatory (blue) combined with the optical image. Astronomers believe that Andromeda, also known as Andromeda Galaxy (M31), and the Milky Way will merge in a few billion years.
In the composite image (insert), hot, X-ray bright gas is seen to envelop the middle of Andromeda. Point sources are also prominent, which mostly reveal pairs of stars that are interacting with each other. Many of these double stars are thought to include white dwarfs pulling large amounts of material away from a companion star. When the amount of gas being dumped onto the white dwarf gets too high a thermonuclear explosion occurs on the surface of the white dwarf, emitting bright X-rays. (Credit: NASA/CXC/MPE/W.Pietsch et al)
Andromeda Galaxy (M31):
A New Look at a Close Neighbor from Chandra