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{{Infobox galaxy
| name = [[NGC天體表|NGC]] 3021
| image = [[File:A cosmological measuring tape.jpg|250px]]
| image_size =
| caption = [[哈伯太空望遠鏡]]拍攝NGC 3021
| epoch = [[J2000]]
| constellation name = [[小狮座]]<ref name="Nasa Hubble"/>
| ra = {{RA|09|50|57.149}}<ref name="NED Caltech">{{cite web|accessdate=October 2, 2015|publisher=[[California Institute of Technology]]|title=NASA/IPAC Extragalactic Database (NED)|url=http://ned.ipac.caltech.edu/cgi-bin/objsearch?search_type=Obj_id&objid=21102|archive-date=2019-12-07|archive-url=https://web.archive.org/web/20191207170424/http://ned.ipac.caltech.edu/cgi-bin/objsearch?search_type=Obj_id&objid=21102|dead-url=no}}</ref>
| dec = {{DEC|33|33|13.07}}<ref name="NED Caltech"/>
| z = {{val|0.00514|0.000013}}<ref name="NED Caltech"/>
| h_radial_v = {{val|1541|4|u=km/s}}<ref name="NED Caltech"/>
| gal_v = {{val|1510|4|u=km/s}}<ref name="NED Caltech"/>
| dist_ly =
| type = SAc<ref>{{cite simbad|title=NGC 3021|access-date=17 January 2017}}</ref>
| mass =
| mass_light_ratio =
| size =
| appmag_v = 10.88<ref name="NED Caltech"/>
| absmag_v = -21.25<ref name="NED Caltech"/>
| size_v = 1.6′ × 0.9′<ref name="NED Caltech"/>
| notes =
| names = [[乌普萨拉总目录|UGC]] 5280, [[2微米全天巡天|2MASX]] J09505711+3333124, [[主要星系目录|PGC]] 28357
}}
'''[[NGC天體表|NGC]] 3021'''是一個小型螺旋星系，在天球上位於[[小獅座]]。該星系距離地球約1億光年<ref name="Nasa Hubble">{{cite web|last=Hille|first=Karl|date=July 30, 2015|accessdate=October 2, 2015|title=Hubble View of a Cosmological Measuring Tape|publisher=NASA|url=https://www.nasa.gov/content/goddard/hubble-view-of-a-cosmological-measuring-tape|archive-date=2016-08-19|archive-url=https://web.archive.org/web/20160819130841/http://www.nasa.gov/content/goddard/hubble-view-of-a-cosmological-measuring-tape/|dead-url=no}}</ref>。該星系由[[威廉·赫歇爾]]發現於1785年12月7日。

1995年時在NGC 3021內發現[[Ia超新星]]{{link-pl|SN 1995al|SN 1995al}}，並且天文學家在該星系內也發現大量造父變星以進行[[哈伯常數]]量測<ref name="Nasa Hubble" />。
[[File:Supernova SN 1995al in NGC 3021.jpg|thumb|1995年在NGC 3021內發現超新星SN 1995al。]]

== 參考資料 ==
{{reflist}}

[[Category:無棒螺旋星系]]
[[Category:特殊星系]]
[[Category:小獅座NGC天體|3021]]
[[Category:UGC天體|05280]]
[[Category:PGC天體|28357]]

{{Galaxy-stub}}

NGC 3021 - 版本历史

imported>InternetArchiveBot：​补救2个来源，并将0个来源标记为失效。) #IABot (v2.0.7

imported>InternetArchiveBot：补救2个来源，并将0个来源标记为失效。) #IABot (v2.0.7