List of Andromeda's satellite galaxies
The Andromeda Galaxy (M31) has satellite galaxies just like the Milky Way. Orbiting M31 are at least 14 dwarf galaxies: the brightest and largest is M32, which can be seen with a backyard telescope. The second brightest and closest one to M32 is M110. The other galaxies are fainter, and were mostly discovered only starting from the 1970s.
On January 11, 2006, it was announced that Andromeda's faint companion galaxies lie on or close to a single plane running through Andromeda's center. This unexpected distribution is not obviously understood in the context of current models for galaxy formation. The plane of satellite galaxies points toward a nearby group of galaxies (M81 Group), possibly tracing the large-scale distribution of dark matter.
Table of known satellites
Andromeda Galaxy's satellites are listed here by discovery (orbital distance is not known).
|Name||Type||Distance from Sun
|Andromeda IV *||dIm?||1972|
|Pegasus Dwarf Spheroidal
|Tidal Stream Northwest
(Tidal Stream E and F)
|Tidal Stream Southwest||2009|
* It is uncertain whether is a companion galaxy of the Andromeda Galaxy.
Interacting with Andromeda
New images from NASA's Spitzer Space Telescope shed light on the Andromeda Galaxy's violent past. The images show that one of Andromeda's satellite galaxies, M32, blasted through one of Andromeda's spiral arms a few million years ago. Infrared pictures of Andromeda's two spiral arms demonstrate that they and the prominent star-forming ring are separate structures. The images also show a hole where the rings seem to split into arcs. This hole is where astronomers believe M32 punched through Andromeda's galactic disk.
- Discovery and analysis of three faint dwarf galaxies and a globular cluster in the outer halo of the Andromeda galaxy, N. F. Martin et.al, 2006.
- Discovery of the Local Group Galaxies
- Moore, Nicole Casal (7 Nov 2011), "Newly found dwarf galaxies could help reveal the nature of dark matter", News Service (University of Michigan), retrieved 10 Dec 2011 (reprinted in R&D Magazine)
- New tidal streams found in Andromeda reveal history of galactic mergers
- Andromeda's thin sheet of satellites - Dark matter filiments or galaxtic cannibalism?
- Strange Setup: Andromeda's Satellite Galaxies All Lined Up