编辑“︁VIRGOHI21”︁

{{Galaxy
 | name =VIRGOHI 21
 | image =
 | epoch = [[J2000]]
 | type = [[暗星系]]
 | ra = {{RA|12|17|53.6}}<ref name="ned">{{cite web
   | title=NASA/IPAC Extragalactic Database
   | work=Results for VIRGOHI 21
   | url=http://nedwww.ipac.caltech.edu/
   | accessdate=2006-11-19
   | archive-date=2011-05-14
   | archive-url=https://web.archive.org/web/20110514100451/http://nedwww.ipac.caltech.edu/
   | dead-url=no
   }}</ref>
 | dec = {{DEC|+14|45|25}}<ref name="ned" />
 | constellation name =[[室女座]]
 | dist_ly = 50 Mly<ref name="PPARC">{{cite web |url=http://www.pparc.ac.uk/Nw/d_galaxy2.asp |title=New evidence for a Dark Matter Galaxy |accessdate=2008-02-26 |format= |publisher=Particle Physics and Astronomy Research Council (PPARC) |deadurl=yes |archiveurl=https://web.archive.org/web/20070310211525/http://www.pparc.ac.uk/Nw/d_galaxy2.asp |archivedate=2007-03-10 }}</ref>
 | z = 1966 [[kilometer|km]]/[[second|s]]<ref name="ned" />
 | appmag_v = 
 | size_v = 
 | notes = 沒有恒星
 | names =
}}

'''VIRGOHI21'''是一个迄今为止最为奇特的星系，其中不包括任何恒星或是行星。 VIRGOHI21星系位于室女座星系群中，2007年6月18日美国康奈尔大学科学家领导的国际天文学研究小组宣布，最终证实该天体构造其实是一个[[暗星系]]，其尺寸与普通的星系差不多，但却完全由[[暗物质]]组成。 

通过设在荷兰的“威斯特博尔克综合射电天文望远镜”（Westerbork Synthesis Radio Telescope），精确测定了该星系的大小。通过[[哈伯太空望远镜]]的进一步观测，发现该星系中不存在一颗恒星，甚至连构成普通恒星和行星的物质也找不到。

在研究超级星系[[M99]](NGC 4254)时意外发现VIRGOHI21星系，在M99星系周围观测到典型的气体发光现象，后来的重力测量结果显示，M99星系旁边肯定存在着一个巨大的重力源，但是却观测不到任何可见的[[星系]]。

据研究资料显示，“VIRGOHI21”[[暗星系]]的质量大约为太阳的1000亿倍，距离地球5000多万光年。

== 參見 ==
*[[暗星系]]
*[[暗物质]]
*[[HVC 127-41-330]]

== 参考资料 ==
{{reflist|2}}

== 外部链接 ==
* [http://news.bbc.co.uk/1/hi/wales/south_east/4288633.stm Astronomers find star-less galaxy] {{Wayback|url=http://news.bbc.co.uk/1/hi/wales/south_east/4288633.stm |date=20080112160730 }} (BBC News), 2005
* [http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2004MNRAS.349..922D&db_key=AST&high=3f5efb5b2204761 A multibeam HI survey of the Virgo cluster - two isolated HI clouds?]，(abstract), Davies, J, et.al, 2004
* [https://web.archive.org/web/20060104064650/http://www.astro.cf.ac.uk/groups/galaxies/dark.pdf A Dark Hydrogen Cloud in the Virgo Cluster]
* [http://space.com/scienceastronomy/050223_dark_galaxy.html First Invisible Galaxy Discovered in Cosmology Breakthrough] {{Wayback|url=http://space.com/scienceastronomy/050223_dark_galaxy.html |date=20101106132406 }}，(SPACE.com), 2005
* [http://www.theregister.co.uk/2005/02/23/galaxy_dark_first/ Astronomers spot first ever dark galaxy] {{Wayback|url=http://www.theregister.co.uk/2005/02/23/galaxy_dark_first/ |date=20160611055704 }} (The Register), 2005
* [http://www.universetoday.com/am/publish/pparc_darkmatter_virgohi.html?1212006 Dark Matter Galaxy?] {{Wayback|url=http://www.universetoday.com/am/publish/pparc_darkmatter_virgohi.html?1212006 |date=20070610011209 }} (UniverseToday)
* [http://www.spacedaily.com/reports/Arecibo_Survey_Produces_Dark_Galaxy_Candidate.html Arecibo Survey Produces Dark Galaxy Candidate]{{Wayback|url=http://www.spacedaily.com/reports/Arecibo_Survey_Produces_Dark_Galaxy_Candidate.html |date=20190803022924 }} (SpaceDaily), 2006
* [http://www2.naic.edu/~rminchin/virgohi21.html 3D Animation from neutral Hydrogen data] {{Wayback|url=http://www2.naic.edu/~rminchin/virgohi21.html |date=20160303185740 }}

{{暗物質}}

[[Category:暗星系]]
[[Category:室女座]]
[[Category:2005年发现的星系]]