NGC 1313
Galaxy in the constellation Reticulum
From Wikipedia, the free encyclopedia
NGC 1313 (also known as the Topsy Turvy Galaxy[2]) is a field galaxy[3] and an irregular galaxy[4] discovered by the Scottish astronomer James Dunlop on 27 September 1826.[5] It has a diameter of about 50,000 light-years, or about half the size of the Milky Way.[6]
| NGC 1313 | |
|---|---|
| |
| Observation data (J2000.0 epoch) | |
| Constellation | Reticulum |
| Right ascension | 03h 18m 15.4s [1] |
| Declination | −66° 29′ 50″ [1] |
| Redshift | 0.001568 [1] |
| Distance | 12.886 Mly[1] |
| Characteristics | |
| Type | SB(s)d[1] |
| Apparent size (V) | 9.1 x 7.1 arcmin[1] |
| Other designations | |
| Topsy Turvy Galaxy, PGC 12286, ESO 082- G 011 | |
NGC 1313 lies within the Virgo Supercluster.[7]
In 2007, a rare WO star was discovered in NGC 1313,[8] currently known by its only designation of [HC2007] 31. It is of spectral type WO3.[8] The derived absolute magnitude is about -5,[8] which is very high for a single WO star. (WOs usually have absolute magnitudes of about -1 to -4) This means that the WO is likely part of a binary or a small stellar association.[8]
Supernovae
Two supernovae have been observed in NGC 1313:
- SN 1962M (Type II, mag. 11.7) was discovered by José Sérsic on 26 November 1962.[9][10]
- SN 1978K (Type IIn, mag. 16) was discovered by Stuart Ryder in January 1990 and originally reported as a nova.[11] However, a search of archival photographs revealed an outburst on 31 July 1978, and all data indicated that it was a very unusual type II supernova.[12]
Features
NGC 1313 has a strikingly uneven shape and its axis of rotation is not exactly in its centre.[13] NGC 1313 also shows strong starburst activity[14] and associated supershells.[15] NGC 1313 is dominated by scattered patches of intense star formation, which gives the galaxy a rather ragged appearance.[16] The uneven shape, the ragged appearance and the strong starburst can all be explained by a galactic collision in the past.[17] However, NGC 1313 seems to be an isolated galaxy and has no direct neighbours. Therefore, it is not clear whether it has swallowed a small companion in its past.[2]
Young, blue stars are scattered across the galaxy.[18] This is evidence of infant mortality in which the young open clusters quickly became gravitationally "unglued", scattering their resident stars into the galaxy.[19] The galaxy bears some resemblance to the Magellanic Clouds[20] and hosts two ultraluminous X-ray sources, called NGC 1313 X-1 and X-2.[21] The former is a rare intermediate-mass black hole.[22][23]
