View source for Palomar 12

{{Short description|Globular cluster in the constellation Capricornus}}
{{Use dmy dates|date=July 2022}}
{{ Infobox globular cluster
| name = Palomar 12
| image = Palomar 12 Hubble.jpg
| image_size = 
| caption = Palomar 12 by [[Hubble Space Telescope]], 3.36{{prime}} view
| epoch = [[Epoch (astronomy)#Julian years and J2000|J2000]]
| class = XII
| constellation = [[Capricornus]]
| ra = {{RA|21|46|38.84}}<ref name=aj140_6_1830/>
| dec = {{DEC|–21|15|09.4}}<ref name=aj140_6_1830/>
| dist_ly = {{Convert|63.6|+/-|2.9|kly|kpc|abbr=on|lk=on}}<ref name="rosenberg"/>
| appmag_v = 11.99
| size_v = 17.4{{prime}}
| radius_ly = 162 ± 8 ly<ref>distance × sin( diameter_angle / 2 ) = 162 ly. radius</ref>
| mass_msol = {{Val|1.59|e=4}}<ref name=apj742_1_51/>
| metal_fe = –0.85<ref name=apj742_1_51/>
| v_hb = 
| age = 6.5 Gyr<ref name="Geisleretal2007"/>
| notes = Probably extragalactic
| names = GCl 123<ref name="simbad" />
}}

'''Palomar 12''' is a [[globular cluster]] in the [[constellation]] [[Capricornus]], and is a member of the [[Palomar Globular Clusters]] group.  

First discovered on the [[National Geographic Society – Palomar Observatory Sky Survey]] plates by [[Robert George Harrington]] and [[Fritz Zwicky]],<ref>{{cite journal
 | last=Abell
 | first = George O.
 | author-link = George Ogden Abell
 | title=Globular Clusters and Planetary Nebulae Discovered on the National Geographic Society-Palomar Observatory Sky Survey
 | journal=Publications of the Astronomical Society of the Pacific
 | date=1955
 | volume=67
 | issue=397
 | pages=258
 | bibcode=1955PASP...67..258A
 | doi=10.1086/126815
| doi-access=free
 }}</ref>
it was initially catalogued as a globular cluster; however, Zwicky came to believe it was actually a nearby dwarf galaxy in the [[Local Group]]. It is a relatively young cluster, being about 30% younger than most of the globular clusters in the [[Milky Way]].<ref name="rosenberg" /> It is metal-rich with a [[metallicity]] of {{nobr|1=[Fe/H] ≈ −0.8}}.<ref name="Geisleretal2007" /> It has an average luminosity distribution of {{nobr|1=M<sub>v</sub> = −4.48}}.<ref name="Bergh2007">{{Cite journal
 | last1 = van den Bergh
 | first1 = Sidney
 | author-link1 = Sidney van den Bergh
 | date = July 2007
 | title = The Luminosity Distribution of Globular Clusters in Dwarf Galaxies
 | journal = The Astronomical Journal
 | volume = 134
 | issue = 1
 | pages = 344–345
 | bibcode = 2007AJ....134..344V
 | doi = 10.1086/518868
|arxiv = 0704.2226 | s2cid = 14209616
 }}</ref>

Based on [[proper motion]] studies, this cluster was first suspected in 2000 to have been captured from the [[Sagittarius Dwarf Elliptical Galaxy]] (''SagDEG'') about 1.7&nbsp;[[Gigaannum|Ga]] ago.<ref>{{cite journal
 | author=D. I. Dinescu
 | author2=S. R. Majewski
 | author3=T. M. Girard
 | author4=K. M. Cudworth
 | title=The Absolute Proper Motion of Palomar 12: A Case for Tidal Capture from the Sagittarius Dwarf Spheroidal Galaxy
 | journal=The Astronomical Journal
 | date=2000
 | volume=120
 | issue=4
 | pages=1892–1905
 | bibcode=2000AJ....120.1892D
 | doi=10.1086/301552
|arxiv = astro-ph/0006314 | s2cid=118898193
 }}</ref>  It is now generally believed to have originated in that galaxy and is associated with the [[Sagittarius Stream]].<ref name="Geisleretal2007" /> It is estimated to be 6.5&nbsp;Gyr old.<ref name="Geisleretal2007" />

==See also==
*[[Messier 54]]

==References==
{{reflist|refs=

<ref name=aj140_6_1830>{{citation | display-authors=1 | last1=Goldsbury | first1=Ryan | last2=Richer | first2=Harvey B. | last3=Anderson | first3=Jay | last4=Dotter | first4=Aaron | last5=Sarajedini | first5=Ata | last6=Woodley | first6=Kristin | title=The ACS Survey of Galactic Globular Clusters. X. New Determinations of Centers for 65 Clusters | journal=The Astronomical Journal | volume=140 | issue=6 | pages=1830–1837 |date=December 2010 | doi=10.1088/0004-6256/140/6/1830 | bibcode=2010AJ....140.1830G | postscript=. |arxiv = 1008.2755 | s2cid=119183070 }}</ref>

<ref name="simbad">{{cite simbad | title=Cl Pal 12 | access-date=2006-11-16 }}</ref>

<ref name="rosenberg">{{citation | display-authors=1 | first1=A. | last1=Rosenberg | first2=I. | last2=Saviane | first3=G. | last3=Piotto | first4=E. V. | last4=Held | title=Young Galactic globular clusters II. The case of Palomar 12 | journal=Astronomy and Astrophysics | date=1998 | volume=339 | pages=61–69 | bibcode=1998A&A...339...61R | arxiv=astro-ph/9809112 | postscript=. }}</ref>

<ref name="Geisleretal2007">{{citation | display-authors=1 | last1=Geisler | first1=Doug | last2=Wallerstein | first2=George | last3=Smith | first3=Verne V. | last4=Casetti-Dinescu | first4=Dana I. | title=Chemical Abundances and Kinematics in Globular Clusters and Local Group Dwarf Galaxies and Their Implications for Formation Theories of the Galactic Halo |date=September 2007 | journal=The Publications of the Astronomical Society of the Pacific | volume=119 | issue=859 | pages=939–961 | bibcode=2007PASP..119..939G | doi=10.1086/521990 | postscript=. |arxiv = 0708.0570 | s2cid=119599242 }}</ref>

<ref name=apj742_1_51>{{citation | display-authors=1 | last1=Boyles | first1=J. | last2=Lorimer | first2=D. R. | last3=Turk | first3=P. J. | last4=Mnatsakanov | first4=R. | last5=Lynch | first5=R. S. | last6=Ransom | first6=S. M. | last7=Freire | first7=P. C. | last8=Belczynski | first8=K. | title=Young Radio Pulsars in Galactic Globular Clusters | journal=The Astrophysical Journal | volume=742 | issue=1 | page=51 |date=November 2011 | doi=10.1088/0004-637X/742/1/51 | bibcode=2011ApJ...742...51B | postscript=. |arxiv = 1108.4402 | s2cid=118649860 }}</ref>

}}

==External links==
{{commonscat}}
* [http://simbad.u-strasbg.fr/sim-id.pl?protocol=html&Ident=Palomar+12 Simbad reference data]
* [http://spider.seds.org/spider/MWGC/pal12.html SEDS: Palomar 12, Capricornus Dwarf]
* {{WikiSky}}
*{{APOD |date=19 February 2015|title=Palomar 12}}


{{Sky|21|46|38.84|-|21|15|09.4|63600}}
{{Milky Way}}
{{Capricornus}}

{{DEFAULTSORT:Palomar 12}}
[[Category:Globular clusters]]
[[Category:Sagittarius Dwarf Spheroidal Galaxy]]
[[Category:Capricornus]]
[[Category:Astronomical objects discovered in 1955|?]]
[[Category:Palomar Observatory|•]]
[[Category:Local Group]]