IC 1613

{{Short description|Irregular dwarf galaxy in the constellation Cetus}}

{{Infobox Galaxy

| image = Dwarf galaxy IC 1613.jpg

| image_scale =

| caption = IC 1613 captured with the VLT's OmegaCAM.{{cite web|title=The Milky Way's Clean and Tidy Galactic Neighbour|url=http://www.eso.org/public/news/eso1603/|access-date=29 January 2016}}

| name = IC 1613

| group_cluster = Local Group

| epoch = J2000

| type = IB(s)m{{cite web

| title=NASA/IPAC Extragalactic Database

| work=Results for IC 1613

| url=http://nedwww.ipac.caltech.edu/

| access-date=2006-11-29 }}

| mass={{val|1.1|0.2|e=8}}

| ra = {{RA|01|04|47.8}}

| dec = {{DEC|+02|07|04}}

| dist_ly = {{val|2.38|0.07|ul=Mly}} ({{val|730|20|ul=kpc}}){{cite journal

|author1=I. D. Karachentsev |author2=V. E. Karachentseva |author3=W. K. Hutchmeier |author4=D. I. Makarov | title=A Catalog of Neighboring Galaxies

| journal=Astronomical Journal

| date=2004

| volume=127

| issue=4

| pages=2031–2068

| bibcode=2004AJ....127.2031K

| doi=10.1086/382905| doi-access=free

}}{{cite journal

|author1=Karachentsev, I. D. |author2=Kashibadze, O. G. | title=Masses of the local group and of the M81 group estimated from distortions in the local velocity field

| journal=Astrophysics

| date=2006

| volume=49

| issue=1

| pages=3–18

| bibcode=2006Ap.....49....3K

| doi=10.1007/s10511-006-0002-6 |s2cid=120973010 }}

| z = {{val|-234|1|ul=km/s}}

| appmag_v = 9.9

| absmag_v = −15.2{{cite journal |last1=Skillman |first1=Evan D. |last2=Hidalgo |first2=Sebastian L. |last3=Weisz |first3=Daniel R. |last4=Monelli |first4=Matteo |last5=Gallart |first5=Carme |last6=Aparicio |first6=Antonio |last7=Bernard |first7=Edouard J. |last8=Boylan-Kolchin |first8=Michael |last9=Cassisi |first9=Santi |last10=Cole |first10=Andrew A. |last11=Dolphin |first11=Andrew E. |last12=Ferguson |first12=Henry C. |last13=Mayer |first13=Lucio |last14=Navarro |first14=Julio F. |last15=Stetson |first15=Peter B. |last16=Tolstoy |first16=Eline |title=The ACS LCID project. X. The star formation history of IC 1613: revisiting the over-cooling problem |journal=The Astrophysical Journal |date=15 April 2014 |volume=786 |issue=1 |pages=44 |doi=10.1088/0004-637X/786/1/44|arxiv=1403.4609 |bibcode=2014ApJ...786...44S }}

| size_v = {{val|16.2|ul='}} × {{val|14.5|u='}}

| constellation name = Cetus

| notes =

| names = UGC 668, DDO 8, PGC 3844, Caldwell 51

}}

File:The sky around the dwarf galaxy IC 1613.jpg towards the bottom of the frame (south) and 29 Ceti to the left (east)]]

IC 1613 (object 1613 in the Index Catalogues (IC), also known as Caldwell 51) is an irregular dwarf galaxy, visible in the constellation Cetus near the star 26 Ceti.{{Cite journal|last1=Cole|first1=Andrew A.|last2=Tolstoy|first2=Eline|last3=Gallagher III|first3=John S.|last4=Hoessel|first4=John G.|last5=Mould|first5=Jeremy R.|last6=Holtzman|first6=Jon A.|last7=Saha|first7=Abhijit|last8=Ballester|first8=Gilda E.|last9=Burrows|first9=Christopher J.|last10=Clarke|first10=John T.|last11=Crisp|first11=David|date=October 1999|title=Stellar Populations at the Center of IC 1613|url=http://stacks.iop.org/1538-3881/118/i=4/a=1657|journal=The Astronomical Journal|volume=118|issue=4|pages=1657–1670|doi=10.1086/301042|bibcode=1999AJ....118.1657C|arxiv=astro-ph/9905350|hdl=11370/f890fe5e-7780-4296-b2e0-a1e6e4b51f11|s2cid=17566586}} It was discovered in 1906 by Max Wolf,{{Cite journal|last1=Cole|first1=Andrew A.|last2=Tolstoy|first2=Eline|last3=Gallagher III|first3=John S.|last4=Hoessel|first4=John G.|last5=Mould|first5=Jeremy R.|last6=Holtzman|first6=Jon A.|last7=Saha|first7=Abhijit|last8=Ballester|first8=Gilda E.|last9=Burrows|first9=Christopher J.|last10=Clarke|first10=John T.|last11=Crisp|first11=David|date=October 1999|title=Stellar Populations at the Center of IC 1613|url=http://stacks.iop.org/1538-3881/118/i=4/a=1657|journal=The Astronomical Journal|volume=118|issue=4|pages=1657–1670|doi=10.1086/301042|bibcode=1999AJ....118.1657C|arxiv=astro-ph/9905350|hdl=11370/f890fe5e-7780-4296-b2e0-a1e6e4b51f11|s2cid=17566586}} and is approaching Earth at 234 km/s.

IC 1613 is a member of the Local Group.{{cite journal|author1=Cole, Andrew A.|author2=Tolstoy, Eline|author3=((Gallagher, John S., III))|author4=Hoessel, John G.|author5=Mould, Jeremy R.|author6=Holtzman, Jon A.|author7=Saha, Abhijit|author8=Ballester, Gilda E.|author9=Burrows, Christopher J.|author10=Clarke, John T.|author11=Crisp, David|date=1999|title=Stellar Populations at the Center of IC 1613|journal=The Astronomical Journal|volume=118|issue=4|pages=1657–1670|arxiv=astro-ph/9905350|bibcode=1999AJ....118.1657C|doi=10.1086/301042|author19=Trauger, John T.|author20=Watson, Alan M.|author21=Westphal, James R.|author18=Stapelfeldt, Karl R.|author17=Scowen, Paul A.|author15=Krist, John E.|author14=Hester, Jeff J.|author13=Grillmair, Carl J.|author12=Griffiths, Richard E.|author16=Meadows, Vikki|s2cid=17566586}} It has played an important role in the calibration of the Cepheid variable period-luminosity relation for estimating distances.{{Cite journal|last1=Cole|first1=Andrew A.|last2=Tolstoy|first2=Eline|last3=Gallagher III|first3=John S.|last4=Hoessel|first4=John G.|last5=Mould|first5=Jeremy R.|last6=Holtzman|first6=Jon A.|last7=Saha|first7=Abhijit|last8=Ballester|first8=Gilda E.|last9=Burrows|first9=Christopher J.|last10=Clarke|first10=John T.|last11=Crisp|first11=David|date=October 1999|title=Stellar Populations at the Center of IC 1613|url=http://stacks.iop.org/1538-3881/118/i=4/a=1657|journal=The Astronomical Journal|volume=118|issue=4|pages=1657–1670|doi=10.1086/301042|arxiv=astro-ph/9905350|bibcode=1999AJ....118.1657C|hdl=11370/f890fe5e-7780-4296-b2e0-a1e6e4b51f11|doi-access=free}} Other than the Magellanic Clouds, it is one of the few Local Group dwarf irregular galaxy where RR Lyrae-type variables have been observed; this factor, along with an unusually low abundance of interstellar dust both within IC 1613 and along the line of sight enable especially accurate distance estimates.{{Cite web | url=https://www.eso.org/public/news/eso1603/ |title = The Milky Way's Clean and Tidy Galactic Neighbour}}

In 1999, Cole et al. used the Hubble Space Telescope to find that the dominant population of this galaxy has an age of ~7 Gyr. Using its Hess diagram, they found that its evolutionary history may be similar to that of the Pegasus Dwarf Irregular Galaxy. Both galaxies are classified as Ir V in the DDO system. Also in 1999, Antonello et al. found five cepheids of Population II in IC 1613, giving self-evident support for the existence of a very old stellar population component of IC 1613. In 1999, King, Modjaz, & Li discovered the first nova ever detected in IC 1613.{{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

}}

File:Caldwell 51 (50290991758).jpg image of the central part of IC 1613, showing the faint galaxies of a background galaxy cluster.]]

IC 1613 contains a WO star known as DR1, which might be the only Wolf–Rayet star in the galaxy,{{Cite journal |last1=Neugent |first1=Kathryn |last2=Massey |first2=Philip |date=2019-08-01 |title=The Wolf–Rayet Content of the Galaxies of the Local Group and Beyond |bibcode=2019Galax...7...74N |journal=Galaxies |volume=7 |issue=3 |pages=74 |doi=10.3390/galaxies7030074|arxiv=1908.06238 |doi-access=free }}{{cite journal|bibcode=2015A&A...581A.110T|arxiv=1507.00839|title=Massive stars on the verge of exploding: The properties of oxygen sequence Wolf–Rayet stars|journal=Astronomy & Astrophysics|volume=581|pages=A110|last1=Tramper|first1=F.|last2=Straal|first2=S. M.|last3=Sanyal|first3=D.|last4=Sana|first4=H.|last5=De Koter|first5=A.|last6=Gräfener|first6=G.|last7=Langer|first7=N.|last8=Vink|first8=J. S.|last9=De Mink|first9=S. E.|author9-link=Selma de Mink|last10=Kaper|first10=L.|year=2015|doi=10.1051/0004-6361/201425390|s2cid=56093231}} although a candidate WC+O binary, SPIRITS14bqe, has been found.{{Cite journal |last1=Lau |first1=Ryan M. |last2=Hankins |first2=Matthew J. |last3=Kasliwal |first3=Mansi M. |last4=Bond |first4=Howard E. |last5=De |first5=Kishalay |last6=Jencson |first6=Jacob E. |last7=Moffat |first7=Anthony F. J. |last8=Smith |first8=Nathan |last9=Williams |first9=Peredur M. |date=2021-03-01 |title=Revealing Efficient Dust Formation at Low Metallicity in Extragalactic Carbon-rich Wolf–Rayet Binaries |bibcode=2021ApJ...909..113L |journal=The Astrophysical Journal |volume=909 |issue=2 |pages=113 |doi=10.3847/1538-4357/abd8cd |s2cid=227053768 |issn=0004-637X |arxiv=2011.09732 |doi-access=free }} A luminous blue variable candidate{{Cite journal|last1=Herrero|first1=A.|last2=Garcia|first2=M.|last3=Uytterhoeven|first3=K.|last4=Najarro|first4=F.|last5=Lennon|first5=D. J.|last6=Vink|first6=J. S.|last7=Castro|first7=N.|title=The nature of V39: an LBV candidate or LBV impostor in the very low metallicity galaxy IC 1613?|journal=Astronomy and Astrophysics|language=en|volume=513|pages=A70|doi=10.1051/0004-6361/200913562|issn=0004-6361|arxiv=1003.0875|bibcode=2010A&A...513A..70H|year=2010|s2cid=54068837}} has been proposed but a revised classification led to a B2.5 III type. Moreover, a rich population of OB-type{{Cite journal|last1=Garcia|first1=M.|last2=Herrero|first2=A.|title=The young stellar population of IC 1613|journal=Astronomy & Astrophysics|language=en|volume=551|pages=A74|doi=10.1051/0004-6361/201219977|issn=0004-6361|arxiv=1211.4582|bibcode=2013A&A...551A..74G|year=2013|s2cid=56300058}} stars and OB associations{{Cite journal|last1=Garcia|first1=M.|last2=Herrero|first2=A.|last3=Castro|first3=N.|last4=Corral|first4=L.|last5=Rosenberg|first5=A.|title=The young stellar population of IC 1613|journal=Astronomy & Astrophysics|language=en|volume=523|doi=10.1051/0004-6361/201015243|issn=0004-6361|bibcode=2010A&A...523A..23G|arxiv=1211.4582|year=2012|pages=A23|s2cid=120326367 }} has been discovered.

There are many faint galaxies close to IC 1613, 14 of which are catalogued as members of a yet-unnamed galaxy cluster located at z≈0.20.{{cite journal

| author=Karl Krienke | author2=Paul W. Hodge

| title=Hubble Space Telescope Photometry of Clusters of Galaxies behind the Dwarf Irregular Galaxies DDO 216 and IC 1613 and the Small Magellanic Cloud

| journal=Publications of the Astronomical Society of the Pacific

| date=2001

| volume=113

| issue=787

| pages=1115–1121

| doi=10.1086/322838| bibcode=2001PASP..113.1115K

}}

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