Leo II (dwarf galaxy)

{{Short description| Dwarf Spheroidal galaxy in the constellation Leo }}

{{Infobox Galaxy

| name = Leo II

| image = LG Leo II (26422781005).jpg

| epoch = J2000

| type = E0 pec {{cite web

| title=NASA/IPAC Extragalactic Database

| work=Results for Leo B

| url=http://nedwww.ipac.caltech.edu/

| accessdate=2006-11-18 }}

| ra = {{RA|11|13|29.2}}

| dec = {{DEC|+22|09|17}}

| dist_ly = 690 ± 70 kly (210 ± 20 kpc)

{{cite journal

|author1=I. D. Karachentsev |author2=V. E. Karachentseva |author3=W. K. Hutchmeier |author4=D. I. Makarov | title=A Catalog of Neighboring Galaxies

| journal=Astronomical Journal

| date=2004

| volume=127

| issue=4

| pages=2031–2068

| bibcode=2004AJ....127.2031K

| doi=10.1086/382905| doi-access=free

}}

{{cite journal

| author=Karachentsev, I. D.

| author2=Kashibadze, O. G.

| title=Masses of the local group and of the M81 group estimated from distortions in the local velocity field

| journal=Astrophysics

| date=2006

| volume=49

| issue=1

| pages=3–18

| bibcode=2006Ap.....49....3K

| doi=10.1007/s10511-006-0002-6 | s2cid=120973010

}}[https://arxiv.org/abs/0708.1853 arXiv:0708.1853]

| 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.

{{cite journal

| author = Tollerud, E.

| display-authors = etal

| title = Hundreds of Milky Way Satellites? Luminosity Bias in the Satellite Luminosity Function

| journal = Astrophysical Journal

| date = Nov 2008

| volume = 688

| issue = 1

| pages = 277–289

| doi = 10.1086/592102

| bibcode=2008ApJ...688..277T

| arxiv=0806.4381

| s2cid = 15468628

}}

Leo II is thought to have a core radius of 178 ± 13 pc and a tidal radius of 632 ± 32 pc.

{{cite journal

| author = Coleman, M.

| display-authors = etal

| title = A Wide-Field View of Leo II: A Structural Analysis Using the Sloan Digital Sky Survey

| journal = Astronomical Journal

| date = Nov 2007

| volume = 134

| issue = 5

| pages = 1938–1951

| bibcode = 2007AJ....134.1938C

| doi = 10.1086/522229

|arxiv = 0708.1853 | s2cid = 14819170

}}

It was discovered in 1950 by Robert George Harrington and Albert George Wilson, from the Mount Wilson and Palomar Observatories in California.

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.

{{cite web

| url = http://subarutelescope.org/Pressrelease/2007/11/28/index.html

| title = Leo II: An Old Dwarf Galaxy with Juvenescent Heart

| accessdate = 25 Nov 2008

| publisher = National Astronomical Observatory of Japan

| date = 28 Nov 2007

}}

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

{{cite journal

| author = Andreas Koch

| display-authors = etal

| title = Stellar Kinematics in the Remote Leo II Dwarf Spheroidal Galaxy—Another Brick in the Wall

| journal = Astronomical Journal

| date = August 2007

| volume = 134

| issue = 2

| pages = 566–578

| url = http://www.iop.org/EJ/abstract/1538-3881/134/2/566

| doi = 10.1086/519380

| bibcode=2007AJ....134..566K

|arxiv = 0704.3437 | s2cid = 15079314

}}