List of Milky Way's satellite galaxies

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The Milky Way has several smaller galaxies gravitationally bound to it, as part of the Milky Way subgroup. This subgroup is part of the local galaxy cluster, the Local Group.[1]

There are between 14 and 26 small galaxies confirmed to be within 420 kiloparsecs (1.4 megalight-years) of the Milky Way, though not all of them are necessarily in orbit. Of those, the only ones visible to the naked eye are the Large and Small Magellanic Clouds, which have been observed since prehistory. Measurements with the Hubble Space Telescope in 2006 suggest the Magellanic Clouds may be moving too fast to be orbiting the Milky Way.[2] Of those galaxies confirmed to be in orbit, the largest is the Sagittarius Dwarf Elliptical Galaxy, which has a diameter of 20,000 light-years (6,100 pc) or roughly a fifth that of the Milky Way.

Characteristics[edit]

Satellite galaxies that orbit, from 1,000 ly (310 pc) of the edge of the disc of the Milky Way Galaxy, to the edge of the dark matter halo of the Milky Way at 980 kly (300 kpc) from the center of the Galaxy,[NB 1] are generally depleted in hydrogen gas compared to those that orbit more distantly. This region is the dense hot gas halo of the Milky Way, which strips cold gas from the satellites. Satellites beyond this region still retain copious quantities of gas.[3][4]

List[edit]

The Milky Way's satellite galaxies include the following:[5]

Name Diameter (kpc) Distance
(kpc)
Type Discovered
Canis Major Dwarf 1.5 8 Irr 2003
Sagittarius Dwarf 2 20 E 1994
LMC 4 48.5 SBm prehistoric
SMC 2 61 Irr prehistoric
Ursa Major II Dwarf 0.2 30 dG D 2006
Ursa Minor Dwarf 0.4 60 dE4 1954
Draco Dwarf 0.7 80 dE0 1954
Sculptor Dwarf Galaxy 0.8 90 dE3 1937
Sextans Dwarf 0.5 90 dE3 1990
Carina Dwarf 0.5 100 dE3 1977
Ursa Major I Dwarf - 100 dG D 2005
Fornax Dwarf 0.6 140 dE2 1938
Leo II 0.7 210 dE0 1950
Leo I 0.5 250 dE3 1950
Leo IV 0.3 160 dSph 2006
Leo V 0.08 180 dSph 2007
Leo T 0.34 420 dSph/dIrr 2006
Boötes I 0.3 60 dSph 2006
Boötes II 0.1 42 dSph 2007
Boötes III 1 46  ? 2009
Coma Berenices 0.14 42 dSph 2006
Segue 2 0.07 35 dSph 2007
Canes Venatici I 2 220 dSph 2006
Canes Venatici II 0.3 155 dSph 2006
Hercules 0.7 135 dSph 2006
Pisces II 0.12 180  ? 2010

Clickable map[edit]

Streams[edit]

The Sagittarius Dwarf is in the process of being consumed by the Milky Way, and is expected to pass through it within the next 100 million years. The Sagittarius Stream is a stream of stars in polar orbit around the Milky Way leeched from the Sagittarius Dwarf. The Virgo Stellar Stream is a stream of stars that is believed to have once been an orbiting dwarf galaxy that has been completely distended by the Milky Way's gravity.

See also[edit]

Footnotes[edit]

  1. ^ The distance to edge of the dark matter halo of the galaxy from its center is the virial radius of a galaxy, Rvir

References[edit]

  1. ^ David G. Turner (15 August 2013). "An Eclectic View of our Milky Way Galaxy". Canadian Journal of Physics (September 2013) 92 (9): 959–963. arXiv:1310.0014. Bibcode:2014CaJPh..92..959T. doi:10.1139/cjp-2013-0429. 
  2. ^ "Magellanic Clouds May Be Just Passing Through". phys.org. 9 January 2007. 
  3. ^ "Milky Way Ransacks Nearby Dwarf Galaxies". SpaceDaily. 17 October 2014. 
  4. ^ "Milky Way ransacks nearby dwarf galaxies". ScienceDaily. 15 October 2014. 
  5. ^ Nils Sjölander. "Milky Way Satellite Galaxies". Archived from the original on 2014-02-19. 

Further reading[edit]