View source for IC 10

{{short description|Irregular starburst galaxy in the constellation Cassiopeia}}
{{Use dmy dates|date=July 2019}}
{{Infobox Galaxy
| image = IC10 BVHa.jpg
| caption = Irregular Galaxy IC 10
| name = IC 10
| type = dIrr IV/BCD<ref name="ned">{{cite web
  | title=NASA/IPAC Extragalactic Database
  | work=Results for IC 10
  | url=http://nedwww.ipac.caltech.edu/cgi-bin/nph-objsearch?search_type=Obj_id&objid=58126&objname=57
  | access-date=2007-03-15 }}</ref>
| epoch = [[Epoch (astronomy)#Julian years and J2000|J2000]]
| ra = {{RA|00|20|17.2917}}<ref name="ned" />
| dec = {{DEC|+59|18|13.867}}<ref name="ned" />
| dist_ly = 2.5 ± 0.5 [[light-year|Mly]] (750 ± 150 [[parsec|kpc]])<ref>{{Cite web|title=NED Query Results for IC 0010|url=http://ned.ipac.caltech.edu/cgi-bin/nDistance?name=IC+0010|access-date=2021-08-08|website=ned.ipac.caltech.edu}}</ref>
| z = {{val|0.001161|0.000003}}<ref name="ned" />
| appmag_v = 10.4 ± 0.2 <ref name="Star-Watcher IC 10">{{cite web
 | title=IC 10
 | work=Star-Watcher
 | url=http://www.star-watcher.org/IC10.html}}</ref>
| size_v = 6.8{{prime}} × 5.9{{prime}}<ref name="ned" />
| size = 5000 [[Light-year|light years]] (diameter)<ref>{{Cite web|title=APOD: 2012 January 4 – Starburst Galaxy IC 10|url=https://apod.nasa.gov/apod/ap120104.html|access-date=2021-08-08|website=apod.nasa.gov}}</ref>
| constellation name = [[Cassiopeia (constellation)|Cassiopeia]]
| notes = mild [[starburst galaxy]]
| names = {{odlist | UGC= 192 | PGC= 1305 | MCG= +10-01-001 | IRAS= 00175+5902}}<ref name="ned" />
}}

'''IC 10''' is an [[irregular galaxy]] in the [[constellation]] [[Cassiopeia (constellation)|Cassiopeia]]. It was discovered by American astronomer [[Lewis A. Swift|Lewis Swift]] on 8 October 1887.<ref name="SEDS">{{cite web | title=IC 10 | work=SEDS Messier Database | url=http://messier.seds.org/xtra/ngc/i0010.html | access-date=2006-05-15}}</ref><ref>{{cite journal |last=Swift |first=Lewis |title=Catalogue No. 7 of Nebulae discovered at the Warner Observatory |journal=Astronomische Nachrichten |volume=120 |pages=33–38 |year=1889 |issue=3 |doi=10.1002/asna.18891200302 |bibcode=1888AN....120...33S}}</ref> In 1935 [[Nicholas Mayall]] became the first to suggest that the object is extragalactic. [[Edwin Hubble]] suspected it might belong to the [[Local Group]] of [[Galaxy|galaxies]], but its status remained uncertain for decades. The [[radial velocity]] of IC 10 was measured in 1962, and it was found to be approaching the [[Milky Way]] at approximately 350&nbsp;km/s, strengthening the evidence for its membership in the Local Group.<ref name="SEDS"/> Its membership in the group was finally confirmed in 1996 by direct measurements of its
distance based on observations of [[Cepheid variable|Cepheid]]s; most estimates place the galaxy 2–3&nbsp;million [[light years]] from Earth, with some estimates ranging from 1.5–4.5 million [[light years]].<ref>{{Cite web|title=NED Query Results for IC 0010|url=http://ned.ipac.caltech.edu/cgi-bin/nDistance?name=IC+0010|access-date=2021-08-08|website=ned.ipac.caltech.edu}}</ref> Despite its closeness, the galaxy is rather difficult to study because it lies near the plane of the [[Milky Way]] and is therefore 
heavily obscured by [[Interstellar medium|interstellar matter]].<ref name="Bergh">{{cite book
| first=Sidney
| last=Van den Bergh
| date=2000
| title=Galaxies of the Local Group
| edition=1st
| publisher=[[Cambridge University Press]]
| isbn=0-521-65181-6 }}</ref>

The apparent distance between IC 10 and the [[Andromeda Galaxy]] is about the same as the apparent distance between the Andromeda Galaxy and the [[Triangulum Galaxy]], which suggests that IC&nbsp;10 may belong to the M31 subgroup.<ref name="Bergh"/>

IC 10 is the only known [[starburst galaxy]] in the Local Group of galaxies; it has many more [[Wolf–Rayet star]]s per square [[parsec|kiloparsec]] (5.1 stars/kpc<sup>2</sup>) than the [[Large Magellanic Cloud]] (2.0 stars/kpc<sup>2</sup>) or the [[Small Magellanic Cloud]] (0.9 stars/kpc<sup>2</sup>). Although the galaxy has a luminosity similar to the SMC, it is considerably smaller, with an estimated diameter of around 5000 [[Light-year|light years]].<ref>{{Cite web|title=APOD: 2012 January 4 – Starburst Galaxy IC 10|url=https://apod.nasa.gov/apod/ap120104.html|access-date=2021-08-08|website=apod.nasa.gov}}</ref> Its higher [[metallicity]] compared to the SMC suggests that star formation activity has continued for a longer time period. The [[H II region]]s in IC&nbsp;10 have all formed recently, within the last 10&nbsp;Myr.<ref name=Cosens>{{cite journal|doi=10.3847/1538-4357/ac52f3|title=Kinematics and Feedback in H II Regions in the Dwarf Starburst Galaxy IC 10|year=2022|last1=Cosens|first1=Maren|last2=Wright|first2=Shelley A.|last3=Murray|first3=Norman|last4=Armus|first4=Lee|last5=Sandstrom|first5=Karin|last6=Do|first6=Tuan|last7=Larson|first7=Kirsten|last8=Martinez|first8=Gregory|last9=Sabhlok|first9=Sanchit|last10=Vayner|first10=Andrey|last11=Wiley|first11=James|journal=The Astrophysical Journal|volume=929|issue=1|page=74|arxiv=2202.04098|bibcode=2022ApJ...929...74C|s2cid=246679827 |doi-access=free }}</ref> The [[Stellar evolution|evolutionary]] status of the Wolf–Rayet stars suggests that they all formed in a relatively short timespan. The ratio between the two types of [[Wolf–Rayet star]]s (WC stars and WN stars) in IC&nbsp;10 is very different from the ratio in other galaxies in the Local Group, which may be somehow due to the starburst nature of the galaxy. Currently, the galaxy produces stars at the rate of 0.04–0.08 [[solar mass]]es per year, which means that the gas supply in the galaxy can last for only a few billion years longer.<ref name="Bergh"/>

Observations of IC 10 in the [[far-infrared]] show that the [[Cosmic dust|dust]] in this mild starburst galaxy is deficient in small grains.<ref>{{cite journal | last=Bolatto | first = A. D. |author2=Jackson, J. M. |author3=Wilson, C. D. |author4=Moriarty-Schieven, G.  | title = Submillimeter Observations of IC 10: The Dust Properties and Neutral Carbon Content of a Low-Metallicity Starburst | date = 2000 | journal=Astrophysical Journal | volume = 532 | issue=2 | pages = 909–921 | bibcode = 2000ApJ...532..909B | doi = 10.1086/308590 |arxiv = astro-ph/9910564 | s2cid = 15330330 }}</ref> It is hypothesized that any small grains that formerly existed were destroyed by strong [[ultraviolet]] radiation in the areas around the hot luminous stars that were formed in the galaxy's recent burst of star formation.<ref name="Bergh2000">{{Cite journal
 | last1 = van den Bergh
 | first1 = Sidney
 | author-link1 = Sidney van den Bergh
 | title = Updated Information on the Local Group
 | date = April 2000
 | journal=The Publications of the Astronomical Society of the Pacific
 | volume = 112
 | issue = 770
 | bibcode = 2000PASP..112..529V
 | pages = 529–536
 | doi = 10.1086/316548
 |arxiv = astro-ph/0001040 | s2cid = 1805423
 }}</ref>

The galaxy has a huge envelope of [[hydrogen]] gas, with an apparent size measuring 68{{prime}} × 80{{prime}}, which is far larger than the apparent size of the galaxy in visible light (5.5{{prime}} × 7.0{{prime}}). IC&nbsp;10 is also unusual in the respect that the visible part of the galaxy seems to rotate in a different direction than the outer envelope.<ref name="Bergh"/> It has an [[H II|H&nbsp;II]] nucleus.<ref name="hoetal1997">{{Cite journal
 | last1 = Ho
 | first1 = Luis C.
 | last2 = Filippenko
 | first2 = Alexei V.
 | last3 = Sargent
 | first3 = Wallace L. W.
 | title = A Search for 'Dwarf' Seyfert Nuclei. III. Spectroscopic Parameters and Properties of the Host Galaxies
 
 | date = October 1997
 | journal = Astrophysical Journal Supplement
 | volume = 112
 | issue = 2
 | pages = 315–390
 | url = http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1997ApJS..112..315H
 | doi = 10.1086/313041
 |arxiv = astro-ph/9704107 |bibcode = 1997ApJS..112..315H | s2cid = 17086638
 }}</ref>

==Gallery==
<gallery>
Spiral, elliptical, irregular IC 10.jpg|IC 10 taken by [[Hubble Space Telescope|Hubble]]<ref>{{cite web |title=Spiral, elliptical, irregular |url=https://www.spacetelescope.org/images/potw1924a/ |website=www.spacetelescope.org |access-date=17 June 2019 |language=en}}</ref>
IC 10 (infrared, red, green).jpg|Amateur near infrared and visible light image of IC 10
</gallery>

== See also ==
* [[List of IC objects]]

==References==
{{reflist|2}}

==External links==
{{commonscat}}
* [http://messier.seds.org/xtra/ngc/i0010.html Irregular Galaxy IC 10 @ SEDS IC objects pages]

{{Sky|00|20|17.2917|+|59|18|13.867|2200000}}
{{Catalogs|IC=10|UGC=192|PGC=1305}}
{{Cassiopeia (constellation)}}

{{DEFAULTSORT:IC 0010}}
[[Category:Irregular galaxies]]
[[Category:Dwarf irregular galaxies]]
[[Category:Starburst galaxies]]
[[Category:Low surface brightness galaxies]]
[[Category:Local Group]]
[[Category:Cassiopeia (constellation)]]
[[Category:IC objects|0010]]
[[Category:UGC objects|00192]]
[[Category:Principal Galaxies Catalogue objects|01305]]
[[Category:Discoveries by Lewis Swift]]
[[Category:Astronomical objects discovered in 1887|18871008]]
[[Category:MCG objects|+10-01-001]]
[[Category:IRAS catalogue objects|00175+5902]]