View source for NGC 3115

{{Short description|Galaxy in the constellation Sextans}}
{{Use mdy dates|date=April 2012}}
{{Infobox Galaxy
| name = [[New General Catalogue|NGC]] 3115
| image = NGC 3115.jpg
| image_size = 300px
| caption = {{longitem|Composite image of NGC 3115 from the [[Chandra X-ray Observatory]] and the  [[Very Large Telescope]]|style=padding: 4px; line-height: 1.3em}}
| type = S0<sup>&minus;</sup><ref>{{cite journal|doi=10.1086/301440|title=The Central Gas Systems of Early-Type Galaxies Traced by Dust Features, Based on the ''Hubble Space Telescope'' WFPC2 Archival Images|year=2000|last1=Tomita|first1=Akihiko|last2=Aoki|first2=Kentaro|last3=Watanabe|first3=Masaru|last4=Takata|first4=Tadafumi|last5=Ichikawa|first5=Shin-Ichi|journal=The Astronomical Journal|volume=120|issue=1|pages=123–130|arxiv=astro-ph/0003431|s2cid=9684945|bibcode=2000AJ....120..123T|doi-access=free}}</ref>
| constellation name = [[Sextans (constellation)|Sextans]]
| epoch = [[J2000]]
| ra = {{RA|10|05|14.0}}<ref name="ned">{{cite web
  | title=NASA/IPAC Extragalactic Database
  | work=Results for NGC 3115
  | url=http://nedwww.ipac.caltech.edu/
  | access-date=October 12, 2006}}</ref>
| dec = {{DEC|-7|43|07}}<ref name="ned" />
| dist_ly = 31.6 ± 1.3 [[light-year|Mly]] (9.7 ± 0.4 [[parsec|Mpc]])<ref name="tonryetal2001">{{cite journal
  | author=J. L. Tonry | display-authors=4 | author2=A. Dressler | author3=J. P. Blakeslee | author4=E. A. Ajhar | author5=A. B. Fletcher | author6=G. A. Luppino | author7=M. R. Metzger | author8=C. B. Moore
  | title=The SBF Survey of Galaxy Distances. IV. SBF Magnitudes, Colors, and Distances
  | journal=Astrophysical Journal
  | date=2001
  | volume=546
  | issue=2
  | pages=681–693
  | bibcode=2001ApJ...546..681T  | doi=10.1086/318301
|arxiv = astro-ph/0011223 | s2cid=17628238 }}</ref>
| z = 663 ± 4 km/[[second|s]]<ref name="ned" />
| appmag_v = 9.9<ref name="ned" />
| size_v = 7.2{{prime}} × 2.5{{prime}}<ref name="ned" />
| names = Spindle Galaxy, UGCA 199, [[Principal Galaxies Catalogue|PGC]] 29265,<ref name="ned" /> [[Caldwell catalogue|Caldwell]]&nbsp;53
}}

'''NGC 3115''' (also called the '''Spindle Galaxy''' or '''Caldwell 53''') is a [[field galaxy|field]] lenticular (S0) galaxy in the [[constellation]] [[Sextans (constellation)|Sextans]].  The galaxy was discovered by [[William Herschel]] on February 22, 1787.<ref>{{cite book|last=O'Meara|first=Stephen James|title=The Caldwell Objects|publisher=[[Cambridge University Press]]|date=2002|location=Cambridge|isbn=978-0-521-82796-6|page=211}}</ref><ref name=1979A&A....74..235M>{{Cite journal |title= The structure of nearby groups of galaxies - Quantitative membership probabilities |author= Materne, J. |date= April 1979 |journal= Astronomy and Astrophysics |volume= 74 |number= 2 |pages= 235–243 |bibcode= 1979A&A....74..235M }}</ref> At about 32 million [[light-years]] away from Earth, it is several times bigger than the [[Milky Way]]. It is a [[lenticular galaxy|lenticular (S0) galaxy]] because it contains a disk and a central bulge of stars, but without a detectable spiral pattern. NGC 3115 is seen almost exactly edge-on, but was nevertheless mis-classified as elliptical. There is some speculation that NGC 3115, in its youth, was a quasar.

One [[supernova]] has been observed in NGC 3115:  SN 1935B (type and mag. unknown).<ref>[https://www.wis-tns.org/object/1935B Transient Name Server entry for SN 1935B.] Retrieved 28 March 2023.</ref><ref>[http://www.cbat.eps.harvard.edu/lists/Supernovae.html Central Bureau for Astronomical Telegrams list of Supernovae.] Retrieved 28 March 2023.</ref>

==Star formation==
NGC 3115 has consumed most of the gas of its youthful accretion disk. It has very little gas and dust left that would trigger new star formation. The vast majority of its component stars are very old.

==Black hole==
In 1992 John Kormendy of the [[University of Hawaii]] and Douglas Richstone of the [[University of Michigan]] announced what was observed to be a [[supermassive black hole]] in the galaxy.<ref>Kormendy, J. and Richstone, D.  "Evidence for a supermassive black hole in NGC 3115", Astrophysical Journal, Part 1, vol. 393, no. 2, July 10, 1992, p. 559-578.</ref>  Based on orbital velocities of the stars in its core, the central black hole has mass measured to be approximately one billion [[solar mass]]es ({{Solar mass|link=y}}). The galaxy appears to have mostly old [[star]]s and little or no activity.  The growth of its [[black hole]] has also stopped.

In 2011, NASA's Chandra X-ray Observatory examined the black hole at the center of the large galaxy. A flow of hot gas toward the supermassive black hole has been imaged, making this the first time clear evidence for such a flow has been observed in any black hole. As gas flows toward the black hole, it becomes hotter and brighter.
The researchers found the rise in gas temperature begins at about 700 light years from the black hole, giving the location of the Bondi radius. This suggests that the black hole in the center of NGC 3115 has a mass of about two billion {{Solar mass}}, supporting previous results from optical observations. This would make NGC 3115 the nearest billion-solar-mass black hole to Earth.

==See also==
*[[NGC 5866]] – another lenticular galaxy sometimes referred to as the Spindle Galaxy

==References==
{{reflist}}

==External links==
{{commonscat}}
*[https://web.archive.org/web/20060827052613/http://chandra.as.utexas.edu/~kormendy/3115-bh.html Chandra Press Release]
*[http://messier.seds.org/xtra/ngc/n3115.html SEDS]: NGC 3115{{WikiSky}}

{{Sky|10|05|14.0|-|07|43|07|31600000}}

{{Catalogs|NGC=3115|C=53|PGC=29265}}
{{Caldwell catalogue}}
{{NGC35}}
{{Sextans}}
{{Authority control}}

{{DEFAULTSORT:NGC 3115}}
[[Category:Lenticular galaxies]]
[[Category:Field galaxies]]
[[Category:Sextans]]
[[Category:NGC objects|3115]]
[[Category:Principal Galaxies Catalogue objects|29265]]
[[Category:Caldwell objects|053b]]
[[Category:Galaxies discovered in 1787|17870222]]
[[Category:UGCA objects]]