Astronomy:Leo V (dwarf galaxy)

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Short description: Galaxy
Leo V Dwarf Galaxy[1]
Observation data (J2000 epoch)
ConstellationLeo
Right ascension 11h 31m 9.6s[1]
Declination+02° 13′ 12″[1]
Distance585 kly (180 kpc)[2]
570 ± 30 kly (175 ± 9 kpc)[3]
Apparent magnitude (V)16 ± 0.4[3]
Characteristics
TypeDSph[2]
Apparent size (V)5.2 ± 1.2′[3]
Other designations
Leo V,[1] PGC 4713563

Leo V is a dwarf spheroidal galaxy situated in the Leo constellation and discovered in 2007 in the data obtained by the Sloan Digital Sky Survey.[2] The galaxy is located at a distance of about 180 kpc from the Sun and moves away from the Sun with the velocity of about 173 km/s.[2] It is classified as a dwarf spheroidal galaxy (dSph) meaning that it has an approximately spherical shape with the half-light radius of about 130 pc.[3][note 1]

Leo V is one of the smallest and faintest satellites of the Milky Way—its integrated luminosity is about 10,000 times that of the Sun (absolute visible magnitude of about −5.2 ± 0.4),[note 1] which is much lower than the luminosity of a typical globular cluster.[3] However, its mass is about 330 thousand solar masses, which means that Leo's V mass to light ratio is around 75. A relatively high mass to light ratio implies that Leo V is dominated by dark matter.[4] The stellar population of Leo V consists mainly of old stars formed more than 12 billion years ago.[2] The metallicity of these stars is also very low at [Fe/H] ≈ −2.0 ± 0.2, which means that they contain 100 times less heavy elements than the Sun.[4]

The galaxy is located only 3 degrees away from another Milky Way satellite, Leo IV. The latter is also closer to the Sun by 20 kpc. These two galaxies may be physically associated with each other.[2] There is evidence that they are connected by a star bridge.[3]

Notes

  1. ↑ 1.0 1.1 From other sources the absolute magnitude is about −4.3 and the half-light radius of 40 pc.[2]

References

  1. ↑ 1.0 1.1 1.2 1.3 "NAME Leo V". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=NAME+Leo+V. 
  2. ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 Belokurov, V. et al. (2008). "Leo V: A companion of a companion of the Milky Way galaxy". The Astrophysical Journal 686 (2): L83–L86. doi:10.1086/592962. Bibcode: 2008ApJ...686L..83B. 
  3. ↑ 3.0 3.1 3.2 3.3 3.4 3.5 de Jong, J. T. A.; Martin, N. F.; Rix, H. W.; Smith, K. W.; Jin, S.; Macciò, A. V. (2010). "The Enigmatic Pair of Dwarf Galaxies Leo Iv and Leo V: Coincidence or Common Origin?". The Astrophysical Journal 710 (2): 1664–1671. doi:10.1088/0004-637X/710/2/1664. Bibcode: 2010ApJ...710.1664D. 
  4. ↑ 4.0 4.1 Walker, M. G. et al. (2009). "Leo V: Spectroscopy of a Distant and Disturbed Satellite". The Astrophysical Journal 694 (2): L144–147. doi:10.1088/0004-637X/694/2/L144. Bibcode: 2009ApJ...694L.144W. 



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