View source for NGC 3109

{{Short description|Galaxy in the constellation Hydra}}
{{Infobox Galaxy
| name               = [[New General Catalogue|NGC]] 3109
| image              = NGC 3109 GALEX WikiSky.jpg
| caption            = NGC 3109 imaged by [[GALEX]] ([[ultraviolet]])
| epoch              = [[J2000]]  
| type               = SB(s)m<ref name="ned">{{cite web
  | title=NASA/IPAC Extragalactic Database
  | work=Results for NGC 3109
  | url=http://nedwww.ipac.caltech.edu/
  | access-date=2006-11-19 }}</ref>
| ra                 = {{RA|10|03|06.9}}<ref name="ned" />
| dec                = {{DEC|-26|09|34}}<ref name="ned" />
| dist_ly            = {{convert|1.333|+/-|0.19|Mpc|Mly|sigfig=4|abbr=on|lk=on}}<ref name="karachentsevetal2004"/><ref name="Karachentsevetal2006"/>
| z                  = 403 ± 1 km/[[second|s]]<ref name="ned" />
| appmag_v           = 10.4<ref name="ned" />
| size               = {{cvt|12.80|x|2.69|kpc|ly|sigfig=3|abbr=on|lk=on|disp=x|<br />(|)|order=flip}}<br />{{small|(''[[Galaxy#Isophotal diameter|diameter]]; [[European Southern Observatory|ESO]] ''D''<sub>25.5</sub> B-band isophote'')}}<ref name=NED/>{{efn|name=Scale}}<br />{{cvt|1.21|x|1.21|kpc|ly|sigfig=4|abbr=on|lk=on|disp=x|<br />(|)|order=flip}}<br />{{small|(''[[Galaxy#Isophotal diameter|diameter]]; [[2MASS]] K-band total isophote'')}}<ref name=NED>{{cite web |url=https://ned.ipac.caltech.edu/cgi-bin/objsearch?objname=NGC+3109&extend=no&hconst=67.74&omegam=0.3089&omegav=0.6911&corr_z=1&out_csys=Equatorial&out_equinox=J2000.0&obj_sort=RA+or+Longitude&of=pre_text&zv_breaker=30000.0&list_limit=5&img_stamp=YES |title=Detailed Information for Object NGC 3109 |work=[[NASA/IPAC Extragalactic Database]] |access-date=September 13, 2023}}</ref>{{efn|name=Scale|The quoted diameters in this infobox was based on NED's provided scale of 0.0065 kpc/arcsec multiplied with the given angular diameters.}}
| size_v             = 19.1{{prime}} × 3.7{{prime}}<ref name="ned" />
| constellation name = [[Hydra (constellation)|Hydra]]
| names              = UGCA 194, [[Principal Galaxies Catalogue|PGC]], 29128,<ref name="ned" /> h 3221, GC 2003<ref name=Ign/>
}}

'''NGC 3109''' is a small barred [[Magellanic spiral|Magellanic type]] [[spiral galaxy|spiral]] or [[irregular galaxy]] around 4.35 [[light-year|Mly]] away in the direction of the constellation of [[Hydra (constellation)|Hydra]]. NGC 3109 is believed to be [[Galactic tide|tidally interacting]] with the [[dwarf elliptical galaxy]] [[Antlia Dwarf]].<ref>Grebel, Gallagher, Harbeck, p.7</ref> It was discovered by [[John Herschel]] on March 24, 1835 while he was in what is now [[South Africa]].<ref name=Ign>[http://www.seds.org/~spider/spider/LG/n3109.html ''Irregular Galaxy NGC 3109''] {{webarchive|url=https://web.archive.org/web/20071107164538/http://www.seds.org/~spider/spider/LG/n3109.html |date=2007-11-07 }}</ref>

==Size and morphology==

NGC 3109 is classified as a [[Magellanic clouds|Magellanic]] type [[irregular galaxy]],<ref name="AparicoEtAl">{{Cite book  | last = Aparicio  | first = Antonio  |author2=Artemio Herrero |author3=F. Sánchez   | title = Stellar astrophysics for the local group: VIII Canary Islands Winter School|
publisher = [[University of Cambridge]]  | date = 1998  | page = 286  | url = https://books.google.com/books?id=3gn5hS2zIkcC&pg=PA286| isbn = 978-0-521-63255-3 }}</ref> but it may in fact be a small [[spiral galaxy]]. Based on the ''D''<sub>25.5</sub> isophote at the B-band with an [[angular diameter]] of {{val|1980|fmt=commas}} [[arcsecond]]s, it has an [[Galaxy#Isophotal diameter|isophotal diameter]] approximately {{convert|12.80|kpc|ly|sigfig=3|abbr=off|lk=on}} across, slightly larger than the [[Large Magellanic Cloud]] but smaller than the [[Triangulum Galaxy]].<ref name="ned" /> If it is a spiral galaxy, it would be the smallest in the [[Local Group]].<ref name="SauvageEtAl">{{Cite book  | last = Sauvage | first = Marc  |author2=Grazyna Stasinska |author3=Daniel Schaerer   | title =The evolution of galaxies: II—basic building blocks, Volume 2|publisher = [[Kluwer Academic Publishers]]  | date = 2002 | pages = 123, 124  | url = https://books.google.com/books?id=xAPX8UfT6qAC&q=ngc+3109&pg=PA123  | isbn = 978-1-4020-0622-7}}</ref> NGC 3109 has a mass of about {{val|2.3|e=9}} times the mass of the [[Sun]] ({{solar mass|link=y}}), of which 20% is in the form of neutral [[hydrogen]].<ref name="Vandenbergh">{{Cite book  | last = van den bergh  | first = Sidney  |  title =  The galaxies of the Local Group | publisher =  University of Cambridge | date =  2000   | pages =  265 | url = https://books.google.com/books?id=NfOwG3cyAGIC&pg=PA265 | isbn = 978-0-521-65181-3}}</ref> It is oriented edge-on from our point of view, and may contain a [[Disc (galaxy)|disk]] and a [[galactic halo|halo]].<ref name="SauvageEtAl"/> The disk appears to be composed of stars of all ages, whereas the halo contains only very old and [[metallicity|metal-poor]] stars.<ref name="HidalgoEtAl">{{Cite journal  | doi = 10.1088/0004-6256/136/6/2332  | last = Hidalgo  | first = Sebastian L.  |display-authors=etal   | title =The Disc-Halo Structure of NGC 3109|journal = [[The Astronomical Journal]]  | volume = 136  | issue = 6  | pages = 2332–2342  | date = 2008  | bibcode=2008AJ....136.2332H| doi-access = free  }}</ref> NGC 3109 does not appear to possess a galactic nucleus.<ref name="Vandenbergh"/>

From measurements of the neutral atomic [[hydrogen]] in the galaxy, it has been found that the disk of NGC 3109 is warped. The warp has the same [[radial velocity]] as gas in the [[Antlia Dwarf]] galaxy, indicating that the two galaxies had a close encounter approximately one billion years ago.<ref name="BarnesdeBlok">{{Cite journal  | doi =  10.1086/321170  | last1 =  Barnes | first1 = D. G. | first2 = W. J. G. | last2 = de Blok  | title =  On the Neutral Gas Content and Environment of NGC 3109 and the Antlia Dwarf Galaxy | journal =  [[The Astronomical Journal]] | volume = 122  | issue =  2  | pages =  825  | date = August 2001  | bibcode=2001AJ....122..825B|arxiv = astro-ph/0107474 | s2cid = 15734118 }}</ref>

==Composition==

Based on spectroscopy of [[Blue supergiant star|blue supergiants]] in NGC 3109, it is known that the galaxy has a low metallicity, similar to that to the [[Small Magellanic Cloud]].<ref name="EvansEtAl"/> It is one of the most metal-poor star-forming galaxies in the Local group.<ref name="Pena">{{Cite journal  | last = Pena  | first = M.  | title = An interesting comparison between PNE and H II regions in NGC 3109 and NGC 6822  | journal = Revista Mexicana de Astronomía y Astrofísica|volume=35  | pages = 74–75  | url = http://www.astroscu.unam.mx/rmaa/RMxAC..35/PDF/RMxAC..35_mpena.pdf  | access-date = 2010-09-24}}</ref>
NGC 3109 seems to contain an unusually large number of [[planetary nebula]]e for its luminosity.<ref name="RicherMcCall">{{Cite journal  | doi = 10.1086/116040  | last = Richer  | first = Michael G.  |author2=Marshall L. McCall   | title = Planetary nebulae and H II regions in NGC 3109  | journal = [[The Astronomical Journal]]  | volume = 103  | pages = 54–59  | date = 1992  | bibcode = 1992AJ....103...54R| doi-access = free  }}</ref> It also contains a substantial amount of [[dark matter]].<ref name="JobinCarignan">
{{Cite journal  | doi = 10.1086/115548  | last = Jobin  | first = Marc  |author2=Carignan, Claude  | title = The dark side of NGC 3109  | journal = [[The Astronomical Journal]]  | volume = 100  | issue = 3  | pages = 648–662  | date = 1990  | bibcode = 1990AJ....100..648J| doi-access = free  }}</ref>

==Location==

NGC 3109 is located about {{convert|1.33|Mpc|Mly}} away, in the constellation [[Hydra (constellation)|Hydra]]. This puts it at the very outskirts of the [[Local Group]].<ref name="EvansEtAl">{{Cite journal  | last = Evans  | first = Chris|display-authors=etal   | title = The ARAUCARIA Project – First Observations of Blue Supergiants in NGC 3109  | journal = The Messenger| volume = 126| pages = 5| url = http://www.eso.org/sci/publications/messenger/archive/no.126-dec06/messenger-no126-5-6.pdf  | access-date = 2010-09-24| bibcode = 2006Msngr.126....5E| year = 2006}}</ref> Its membership of the Local Group has been questioned, because it seems to be receding faster than estimates of the Local Group's [[escape velocity]].<ref name="Plotner">{{Cite web  | last = Plotner  | first = Tammy  | title =Turning the Tides – NGC 3109 by Ken Crawford   | publisher =  [[Universe Today]] | date = 2009-05-18  | url =  http://www.universetoday.com/27388/turning-the-tides-ngc-3109-by-ken-crawford/| access-date = 2010-09-24}}</ref> It is distant enough from the largest members of the Local Group that it has not been tidally influenced by them.<ref name="Pena"/>

==Luminous Blue Variable==
Although no [[supernova]]e have been observed in NGC 3109 yet, a [[luminous blue variable]], designated AT{{nbsp}}2018akx (type LBV, mag. 17.5), was discovered on 22 March 2018.<ref>{{cite web | website=Transient Name Server | title=AT{{nbsp}}2018akx | url=https://www.wis-tns.org/object/2005cz | publisher = [[International_Astronomical_Union|IAU]] | access-date=31 August 2024}}</ref>

== Gallery ==
<gallery>
File:NGC 3109 814 606.jpg|NGC 3109 with [[Hubble Space Telescope|Hubble]]
File:NGC 3109 legacy dr10.jpg|NGC 3109 with the [[Dark Energy Spectroscopic Instrument#DESI Legacy Imaging Surveys|legacy surveys]]
</gallery>

==Notes==
{{notelist|refs=


}}

== See also ==
* [[List of NGC objects (3001–4000)]]

==References==
{{reflist|refs=

<ref name="karachentsevetal2004">{{cite journal
  | author=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
  | type=abstract| doi-access=free
  }}</ref>

<ref name="Karachentsevetal2006">{{cite journal
  | author=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
 }}</ref>

}}

==Further reading==
*Grebel, Gallagher, Harbeck (2003) [https://arxiv.org/abs/astro-ph/0301025 ''The Progenitors of Dwarf Spheroidal Galaxies'' ] ArXiv.org. retrieved November 2007

==External links==
{{commons category}}
* {{WikiSky}}


{{Ngc35}}
{{Hydra (constellation)}}
{{Sky|10|03|06.9|-|26|09|34|4300000}}

{{DEFAULTSORT:NGC 3109}}
[[Category:Magellanic spiral galaxies]]
[[Category:Barred spiral galaxies]]
[[Category:NGC 3109 subgroup]]
[[Category:Hydra (constellation)]]
[[Category:NGC objects|3109]]
[[Category:Principal Galaxies Catalogue objects|29128]]
[[Category:Local Group]]
[[Category:Astronomical objects discovered in 1835|18350324]]
[[Category:UGCA objects]]