Leo II (dwarf galaxy)

Leo II
Observation data (J2000 epoch)
Constellation Leo
Right ascension 11h 13m 29.2s [1]
Declination +22° 09′ 17″ [1]
Redshift 0.000264 (79 ± 1 km/s) [1]
Distance

690 ± 70 kly (210 ± 20 kpc)[2]

[3]
Apparent magnitude (V) 12.6 [1]
Characteristics
Type E0 pec [1]
Apparent size (V) 12.0 x 11.0 arcmin [1]
Other designations
PGC 34176, DDO 93

Leo II (or Leo B) is a dwarf spheroidal galaxy about 690,000 light-years away in the constellation Leo. As of October 2008 it is one of 24 known satellite galaxies of the Milky Way.[4] As of 2007 Leo II is thought to have a core radius of 178 ± 13 pc and a tidal radius of 632 ± 32 pc.[5] It was discovered in 1950 by Robert George Harrington and Albert George Wilson, from the Mount Wilson and Palomar Observatories in California.

Recent Findings

In 2007 a team of 15 scientists observed Leo II through the 8.2 meter Subaru optical-infrared telescope in Mauna Kea, Hawaii. Over 2 nights, 90 minutes of exposures were taken and 82,252 stars were detected down to a visible magnitude of 26. They found that Leo II consists largely of metal-poor older stars, a sign that it has survived the galactic cannibalism under which massive galaxies (e.g., the Milky Way) consume smaller galaxies to attain their extensive size.[6]

Observation at ESO estimates Leo II's mass to be (2.7 ± 0.5)×107 M⊙.[7]

See also

References

  1. 1 2 3 4 5 6 "NASA/IPAC Extragalactic Database". Results for Leo B. Retrieved 2006-11-18.
  2. ↑ I. D. Karachentsev; V. E. Karachentseva; W. K. Hutchmeier; D. I. Makarov (2004). "A Catalog of Neighboring Galaxies". Astronomical Journal. 127 (4): 2031–2068. Bibcode:2004AJ....127.2031K. doi:10.1086/382905.
  3. ↑ Karachentsev, I. D.; Kashibadze, O. G. (2006). "Masses of the local group and of the M81 group estimated from distortions in the local velocity field". Astrophysics. 49 (1): 3–18. Bibcode:2006Ap.....49....3K. doi:10.1007/s10511-006-0002-6.arXiv:0708.1853
  4. ↑ Tollerud, E.; et al. (Nov 2008). "Hundreds of Milky Way Satellites? Luminosity Bias in the Satellite Luminosity Function". Astrophysical Journal. 688 (1): 277–289. arXiv:0806.4381v2Freely accessible. Bibcode:2008ApJ...688..277T. doi:10.1086/592102.
  5. ↑ Coleman, M.; et al. (Nov 2007). "A Wide-Field View of Leo II: A Structural Analysis Using the Sloan Digital Sky Survey". Astronomical Journal. 134 (5): 1938–1951. arXiv:0708.1853Freely accessible. Bibcode:2007AJ....134.1938C. doi:10.1086/522229.
  6. ↑ "Leo II: An Old Dwarf Galaxy with Juvenescent Heart". National Astronomical Observatory of Japan. 28 Nov 2007. Retrieved 25 Nov 2008.
  7. ↑ Andreas Koch; et al. (August 2007). "Stellar Kinematics in the Remote Leo II Dwarf Spheroidal Galaxy—Another Brick in the Wall". Astronomical Journal. 134 (2): 566–578. arXiv:0704.3437Freely accessible. Bibcode:2007AJ....134..566K. doi:10.1086/519380.

Coordinates: 11h 13m 29.2s, +22° 09′ 17″

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