IC 10

Infobox Galaxy


caption = Irregular Galaxy IC 10.
name = IC 10
type = dIrr IV/BCDcite 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
accessdate=2007-03-15 ]
epoch = J2000
ra = RA|00|20|17.3
dec = DEC|+59|18|14
dist_ly = 2.2 ± 0.2 Mly (660 ± 60 kpc)cite journal
author=Karachentsev, I. D.; Kashibadze, O. G.
title=Masses of the local group and of the M81 group estimated from distortions in the local velocity field
journal=Astrophysics
year=2006
volume=49
issue=1
pages=3–18
url=http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2006Ap.....49....3K | doi=10.1007/s10511-006-0002-6]
z = -348 ± 1 km/s
appmag_v = 10.4 ± 0.2Fact|date=February 2007
size_v = 6′.8 × 5′.9
constellation name = Cassiopeia
notes = mild starburst galaxy
names = UGC 192, PGC 1305

IC 10 is an irregular galaxy in the constellation Cassiopeia. It was discovered by Lewis Swift in 1887.cite web
title=IC 10
work=SEDS Messier Database
url=http://www.seds.org/messier/xtra/ngc/i0010.html
accessdate=2006-05-15] Nicholas U. Mayall was the first to suggest that the object is extragalactic in 1935. Edwin Hubble suspected it might belong to the Local Group of galaxies, but its status remained uncertain for decades. The radial velocity of IC 10 was measured in 1962, and it was found to be receding from the Milky Way at approximately350 km/s, strengthening the evidence for its membership in the Local Group. Its membership in the group was finally confirmed in 1996 by direct measurements of itsdistance based on observations of Cepheids. 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 matter.cite book
first=Sidney
last=Van den Bergh
year=2000
title=Galaxies of the Local Group
edition=1st edition
publisher=Cambridge University Press
id=ISBN 0-521-65181-6 ]

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 10 may belong to the M31 subgroup.

IC 10 is the only known starburst galaxy in the Local Group of galaxies. It has many more Wolf-Rayet stars per square kiloparsec (5.1 stars/kpc²) than the Large Magellanic Cloud (2.0 stars/kpc²) or the Small Magellanic Cloud (0.9 stars/kpc²). Although the galaxy has a similar luminosity to the SMC, it is considerably smaller. Its higher metallicity compared to the SMC suggests that star formation activity has continued for a longer time period. The 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 stars (WC stars and WN stars) in IC 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 masses per year, which means that the gas supply in the galaxy can last for only a few billion years longer.

Observations of IC 10 in the far-infrared show that the dust in this mild starburst galaxy is deficient in small grains. [cite journal | last=Bolatto | first = A. D. | coauthors = Jackson, J. M., Wilson, C. D., Moriarty-Schieven, G. | title = Submillimeter Observations of IC 10: The Dust Properties and Neutral Carbon Content of a Low-Metallicity Starburst | year = 2000 | journal = ApJ | volume = 532 | pages = 909–921 | url = http://adsabs.harvard.edu/abs/2000ApJ...532..909B | doi = 10.1086/308590 ] 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. citation
last1 = van den Bergh
first1 = Sidney
authorlink1 = Sidney van den Bergh
title = Updated Information on the Local Group
year = 2000
date = April 2000
journal = The Publications of the Astronomical Society of the Pacific
volume = 112
issue = 770
url = http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2000PASP..112..529V
pages = 529–536
doi = 10.1086/316548]

The galaxy has a huge envelope of hydrogen gas, with an apparent size measuring 68′ × 80′, which is far larger than the apparent size of the galaxy in visible light (5.5′ × 7.0′). IC 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. It has a H II nucleus.citation
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
year = 1997
date = October 1997
periodical = Astrophysical Journal Supplement
volume = 112
pages = 315
url = http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1997ApJS..112..315H
doi = 10.1086/313041
author = Ho, Luis C.
journal = The Astrophysical Journal Supplement Series]

References

External links

* [http://www.seds.org/messier/xtra/ngc/i0010.html Irregular Galaxy IC 10 @ SEDS IC objects pages]
* [http://starrymirror.com/blackholeic10.htm Black Hole In IC10 Smashes All Records]