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]
Type	E0 pec [1]
Apparent dimensions (V)	12.0 x 11.0 arcmin [1]
Apparent magnitude (V)	12.6 [1]
Other designations
PGC 34176
See also: Galaxy, List of galaxies

Leo II (or Leo B) is an 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 G. 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 of 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

• Dwarf Galaxy
• Local Group, a description of the group of galaxies that includes the Milky Way

References

1. ^ ^{a b c d e f} "NASA/IPAC Extragalactic Database". Results for Leo B. http://nedwww.ipac.caltech.edu/. 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:0806.4381. 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. Bibcode 2007AJ....134.1938C. doi:10.1086/522229.  arXiv:0806.4381
6. ^ "Leo II: An Old Dwarf Galaxy with Juvenescent Heart". National Astronomical Observatory of Japan. 28 Nov 2007. http://subarutelescope.org/Pressrelease/2007/11/28/index.html. 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. Bibcode 2007AJ....134..566K. doi:10.1086/519380. http://www.iop.org/EJ/abstract/1538-3881/134/2/566. 

• Harrington R. G., Wilson A. G. (1950). "Two New Stellar Systems in Leo". Publications of the Astronomical Society of the Pacific 62 (365): 118–120. Bibcode 1950PASP...62..118H. doi:10.1086/126249. 

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