Leo II (dwarf galaxy) explained

Leo II
Epoch:	J2000
Type:	E0 pec ^[1]
Dist Ly:	690 ± 70 kly (210 ± 20 kpc)^[2] ^[3]
Z:	0.000264 (79 ± 1 km/s)
Appmag V:	12.6
Size V:	12.0 x 11.0 arcmin
Constellation Name:	Leo
Names:	PGC 34176, DDO 93

Leo II (or Leo B) is a dwarf spheroidal galaxy about 690,000 light-years away in the constellation Leo. It is one of 24 known satellite galaxies of the Milky Way.^[4] 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

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

References

• Harrington R. G. . Wilson A. G. . 1950 . Two New Stellar Systems in Leo . . 62 . 365. 118–120 . 10.1086/126249 . 1950PASP...62..118H . free .

Notes and References

1. Web site: NASA/IPAC Extragalactic Database . Results for Leo B . 2006-11-18 .
2. I. D. Karachentsev . V. E. Karachentseva . W. K. Hutchmeier . D. I. Makarov . A Catalog of Neighboring Galaxies . Astronomical Journal . 2004 . 127 . 4 . 2031–2068 . 2004AJ....127.2031K . 10.1086/382905. free .
3. Karachentsev, I. D. . Kashibadze, O. G. . Masses of the local group and of the M81 group estimated from distortions in the local velocity field . Astrophysics . 2006 . 49 . 1 . 3–18 . 2006Ap.....49....3K . 10.1007/s10511-006-0002-6 . 120973010 . arXiv:0708.1853
4. Tollerud, E.. etal. Hundreds of Milky Way Satellites? Luminosity Bias in the Satellite Luminosity Function. Astrophysical Journal. Nov 2008. 688. 1. 277–289. 10.1086/592102. 2008ApJ...688..277T. 0806.4381. 15468628.
5. Coleman, M.. etal. A Wide-Field View of Leo II: A Structural Analysis Using the Sloan Digital Sky Survey. Astronomical Journal. Nov 2007. 134. 5. 1938–1951. 2007AJ....134.1938C. 10.1086/522229. 0708.1853 . 14819170.
6. Web site: Leo II: An Old Dwarf Galaxy with Juvenescent Heart. 25 Nov 2008. National Astronomical Observatory of Japan. 28 Nov 2007.
7. Andreas Koch. etal. Stellar Kinematics in the Remote Leo II Dwarf Spheroidal Galaxy—Another Brick in the Wall. Astronomical Journal. August 2007. 134. 2. 566–578. 10.1086/519380. 2007AJ....134..566K. 0704.3437 . 15079314.