View source for NGC 6934

{{Short description|Globular cluster in the constellation Delphinus}}
{{Infobox globular cluster
 | name      = NGC 6934
 | image     = [[Image:NGC 6934 Hubble WikiSky.jpg|300px]]
 | caption   = NGC 6934 by [[Hubble Space Telescope]]; 3.5{{prime}} view
 | credit    = 
 | epoch     = [[J2000]]
 | constellation = [[Delphinus]]
 | ra        = {{RA|20|34|11.37}}<ref name=Goldsbury2010/>
 | dec       = {{DEC|+07|24|16.1}}<ref name=Goldsbury2010/>
 | dist_ly   = {{Convert|16|kpc|kly|order=flip|abbr=on|lk=on}}<ref name=apj670_1_363/>
 | size_v    = {{val|1.20|ul=arcmin}}<ref name=Forbes2008/>
 | appmag_v  = 8.83<ref name="seds" />
 | absmag_v  = −7.65<ref name=Dinescu2001/>
 | class     = VIII<ref name=hcob849_11/>
 | mass_msol = {{Val|2.95|e=5}}<ref name=apj742_1_51/>
 | radius_ly = 
 | metal_fe  = –1.47<ref name=apj742_1_51/>
 | v_hb      = 
 | age       = 
 | notes     = 
 | names     = {{odlist | name=[[Caldwell catalogue|Caldwell]] 47 | NGC=6934 }}<ref name=simbad/>
}}

'''NGC 6934''' (also known as '''Caldwell 47''') is a [[globular cluster]] of stars in the northern [[constellation]] of [[Delphinus]], about {{Convert|16|kpc|kly|disp=out|abbr=off|lk=on}} distant from the [[Sun]].<ref name=apj670_1_363/> It was discovered by the German-born astronomer [[William Herschel]] on 24 September 1785.<ref name="seds" /> The cluster is following a highly eccentric orbit (with an [[Orbital eccentricity|eccentricity]] of 0.81) through the [[Milky Way]] along an [[orbital plane]] that is inclined by 73° to the [[galactic plane]]. It may share a common dynamic origin with [[NGC 5466]].<ref name=Dinescu2001/> As of 2018, it has been poorly studied.<ref name=Marino2018/>

This appears to be a [[Oosterhoff type I]] cluster with an intermediate [[metallicity]].<ref name=Kaluzny2001/> It has an [[Shapley–Sawyer Concentration Class]] of VIII,<ref name=hcob849_11/> with a [[core radius]] of {{val|15|u=arcsecond}}<ref name=apj670_1_363/> and a half-light radius of {{val|36|u=arcsecond}}.<ref name=Forbes2008/> The estimated mass is 295,000 times the [[mass of the Sun]].<ref name=apj742_1_51/> The cluster displays photometric anomalies, with a split [[subgiant]] branch on the [[HR diagram]].<ref name=Marino2018/> Searches for [[variable star]]s have discovered 85 in the cluster field, of which 79 are of the [[RR Lyrae variable|RR Lyrae]] class and one is a [[SX Phoenicis variable|SX Phe variable]].<ref name=Kaluzny2001/> There is some evidence for a [[tidal tail]].<ref name=Wilhelm2002/>

==References==
{{reflist|refs=

<ref name=simbad>{{cite simbad
 | title=NGC 6934 | access-date=2020-10-08 }}</ref>

<ref name="seds">{{citation
 | title=NGC 6934  
 | publisher=[[Students for the Exploration and Development of Space|SEDS]]
 | url=http://spider.seds.org/spider/MWGC/n6934.html  
 | access-date=2010-10-09 }}</ref>

<ref name=Dinescu2001>{{cite journal
 | title=Orbits of Globular Clusters in the Outer Galaxy: NGC 7006
 | last1=Dinescu | first1=Dana I. | last2=Majewski | first2=Steven R.
 | last3=Girard | first3=Terrence M. | last4=Cudworth | first4=Kyle M.
 | display-authors=1 | journal=The Astronomical Journal
 | volume=122 | issue=4 | pages=1916–1927 | date=October 2001
 | arxiv=astro-ph/0106259 | bibcode=2001AJ....122.1916D 
 | doi=10.1086/323094 | s2cid=1232455 }}</ref>

<ref name=Kaluzny2001>{{cite journal
 | title=Image-Subtraction Photometry of Variable Stars in the Field of the Globular Cluster NGC 6934
 | display-authors=1 | last1=Kaluzny | first1=J.
 | last2=Olech | first2=A. | last3=Stanek | first3=K. Z.
 | journal=The Astronomical Journal
 | volume=121 | issue=3 | pages=1533–1550 | date=March 2001
 | arxiv=astro-ph/0010303 | bibcode=2001AJ....121.1533K 
 | doi=10.1086/319411 | s2cid=14431121 }}</ref>

<ref name=Wilhelm2002>{{cite journal
 | title=Does NGC 6934 Have a Tidal Tail?
 | display-authors=1 | last1=Wilhelm | first1=R.
 | last2=Groning | first2=L. | last3=Edmiston | first3=G.
 | journal=Bulletin of the American Astronomical Society
 | volume=34 | page=1101 | date=December 2002
 | bibcode=2002AAS...201.0702W }}</ref>

<ref name=Marino2018>{{cite journal
 | title=Metallicity Variations in the Type II Globular Cluster NGC 6934
 | last1=Marino | first1=A. F. | last2=Yong | first2=D.
 | last3=Milone | first3=A. P. | last4=Piotto | first4=G.
 | last5=Lundquist | first5=M. | last6=Bedin | first6=L. R.
 | last7=Chené | first7=A. -N. | last8=Da Costa | first8=G.
 | last9=Asplund | first9=M. | last10=Jerjen | first10=H.
 | display-authors=1 | journal=The Astrophysical Journal
 | volume=859 | issue=2 | id=81 | pages=20 | date=June 2018
 | arxiv=1804.04158 | bibcode=2018ApJ...859...81M 
 | doi=10.3847/1538-4357/aabdea | s2cid=119461759 | doi-access=free }}</ref>

<ref name=Forbes2008>{{cite journal
 | title=Uniting old stellar systems: from globular clusters to giant ellipticals
 | last1=Forbes | first1=Duncan A. | last2=Lasky | first2=Paul
 | last3=Graham | first3=Alister W. | last4=Spitler | first4=Lee
 | display-authors=1 | journal=Monthly Notices of the Royal Astronomical Society
 | volume=389 | issue=4 | pages=1924–1936 | date=October 2008
 | bibcode=2008MNRAS.389.1924F | arxiv=0806.1090
 | doi=10.1111/j.1365-2966.2008.13739.x | doi-access=free | s2cid=14108457 }}</ref>

<ref name=Goldsbury2010>{{cite journal
 | title=The ACS Survey of Galactic Globular Clusters. X. New Determinations of Centers for 65 Clusters
 | 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
 | display-authors=1 | journal=The Astronomical Journal
 | volume=140 | issue=6 | pages=1830–1837 | date=December 2010
 | arxiv=1008.2755 | bibcode=2010AJ....140.1830G 
 | doi=10.1088/0004-6256/140/6/1830 | s2cid=119183070 }}</ref>

<ref name=hcob849_11>{{citation
 | title=A Classification of Globular Clusters
 | last1=Shapley | first1=Harlow | last2=Sawyer | first2=Helen B.
 | journal=Harvard College Observatory Bulletin
 | volume=849 | issue=849 | pages=11–14 | date=August 1927
 | bibcode=1927BHarO.849...11S | postscript=. }}</ref>

<ref name=apj670_1_363>{{citation
 | title=A 1.4 GHz Arecibo Survey for Pulsars in Globular Clusters
 | display-authors=1 | last1=Hessels | first1=J. W. T.
 | last2=Ransom | first2=S. M. | last3=Stairs | first3=I. H.
 | last4=Kaspi | first4=V. M. | last5=Freire | first5=P. C. C.
 | journal=The Astrophysical Journal
 | volume=670 | issue=1 | pages=363–378 | date=November 2007
 | bibcode=2007ApJ...670..363H  | arxiv=0707.1602
 | doi=10.1086/521780 | s2cid=16914232 | postscript=. }}</ref>

<ref name=apj742_1_51>{{citation
 | title=Young Radio Pulsars in Galactic Globular Clusters
 | 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.
 | display-authors=1 | journal=The Astrophysical Journal
 | volume=742 | issue=1 | page=51 | date=November 2011
 | bibcode=2011ApJ...742...51B | arxiv=1108.4402
 | doi=10.1088/0004-637X/742/1/51 | s2cid=118649860 | postscript=. }}</ref>

}}

==External links==
* {{commonscat-inline}}
* {{WikiSky}}
* [http://www.spacetelescope.org/images/potw1023a/ A Distant Backwater of the Milky Way] — [[ESA]]/[[Hubble Space Telescope|Hubble]] Picture of the Week

{{Sky|20|34|11.5|+|07|24|14.9|50000}}
{{Catalogs|NGC=6934|C=47}}
{{Caldwell catalogue}}
{{Ngc70}}
{{Delphinus}}

{{DEFAULTSORT:NGC 6934}}
[[Category:Globular clusters]]
[[Category:Delphinus]]
[[Category:NGC objects|6934]]
[[Category:Caldwell objects|047b]]
[[Category:Astronomical objects discovered in 1785]]