Messier 83

Messier 83 or M83, also known as the Southern Pinwheel Galaxy and NGC 5236, is a barred spiral galaxy<ref name=WISE /> approximately 15 million light-years away in the constellation borders of Hydra and Centaurus. Nicolas-Louis de Lacaille discovered M83 on 17 February 1752 at the Cape of Good Hope.<ref name="jones1991" /> Charles Messier added it to his catalogue of nebulous objects (now known as the Messier Catalogue) in March 1781.<ref name="jones1991" />

It is one of the closest and brightest barred spiral galaxies in the sky, and is visible with binoculars.<ref name=mo /> It has an isophotal diameter at about Template:Convert. Its nickname of the SouthernTemplate:Efn Pinwheel derives from its resemblance to the Pinwheel Galaxy (M101).

Characteristics

Messier 83 captured by the Wide Field Imager at ESO's La Silla Observatory in September 2008

M83 is a massive, grand design spiral galaxy.<ref name=Calzetti1999 /> Its morphological classification in the De Vaucouleurs system is SAB(s)c,<ref name=vaucoulerus1991 /> where the 'SAB' denotes a weak-barred spiral, '(s)' indicates a pure spiral structure with no ring, and 'c' means the spiral arms are loosely wound.<ref name=deVaucouleurs1963 /> The peculiar dwarf galaxy NGC 5253 lies near M83,<ref name=Thim2003 /> and the two likely interacted within the last billion years resulting in starburst activity in their central regions.<ref name=Calzetti1999 />

The star formation rate in M83 is higher along the leading edge of the spiral arms, as predicted by density wave theory.<ref name=Villa2012 /> NASA's Galaxy Evolution Explorer project on 16 April 2008 reported finding large numbers of new stars in the outer reaches of the galaxy—Template:Val from the center. It had been thought that these areas lacked the materials necessary for star formation.<ref name="galex" /><ref name=Cong2008 />

In April 2025 it was published that first clues were found for the possible existence of a supermassive black hole at the center of M83.<ref>Template:Cite journal</ref>

Supernovae

Six supernovae have been observed in M83:

• SN 1923A (type unknown, mag. 14) was discovered by Carl Otto Lampland on 5 May 1923.<ref>Template:Cite web</ref><ref>Template:Cite journal</ref>
• SN 1945B (type unknown, mag. 14.2) was discovered by William Liller on 13 July 1945.<ref>Template:Cite web</ref><ref>Template:Cite journal</ref>
• SN 1950B (type unknown, mag. 14.5) was discovered by Guillermo Haro on 15 March 1950.<ref>Template:Cite web</ref>
• SN 1957D (type unknown, mag. 15)<ref name=Romaniello2005 /> was discovered by Howard S. Gates on 28 December 1957.<ref>Template:Cite web</ref><ref>Template:Cite web</ref><ref>Template:Cite journal</ref>
• SN 1968L (Type II-P, mag. 11.9)<ref>Template:Cite journal</ref><ref>Template:Cite web</ref> was discovered by J. C. Bennett on 17 July 1968.<ref>Template:Cite web</ref>
• SN 1983N (Type Ia, mag. 11.9) was discovered by Robert Evans from Australia on 3 July 1983.<ref>Template:Cite web</ref><ref name=Thompson_et_al_1983 /> On 6 July, it was observed with the Very Large Array and became the first Type I supernova to have a radio emission detected. The supernova reached peak optical brightness on 17 July, achieving an apparent visual magnitude of 11.54.<ref name=Sramek_et_al_1984 /> Although identified as Type I, the spectrum was considered peculiar. A year after the explosion, about Template:Val of iron was discovered in the ejecta. This was the first time that such a large amount of iron was unambiguously detected from a supernova explosion.<ref name=Graham_et_al_1986 /> SN 1983N became the modern prototype of a hydrogen deficient Type Ib supernova, with the progenitor being inferred as a Wolf–Rayet star.<ref name=Gaskell_et_al_1986 />

Environment

M83 is at the center of one of two subgroups within the Centaurus A/M83 Group, a nearby galaxy group.<ref name="karachentsevetal2002" /> Centaurus A is at the center of the other subgroup. These are sometimes identified as one group,<ref name="nbg" /><ref name="fouqueetal1992" /> and sometimes as two.<ref name="garcia1993" /> However, the galaxies around Centaurus A and the galaxies around M83 are physically close to each other, and both subgroups appear not to be moving relative to each other.<ref name="karachentsev2005" />

See also

• List of Messier objects
• M83 (band), the band named after the galaxy

External links

• Template:WikiSky
• ESO Photo Release eso0136, An Infrared Portrait of the Barred Spiral Galaxy Messier 83
• M83, SEDS Messier pages
• Spiral Galaxy Messier 83 at the astro-photography site of Takayuki Yoshida
• M83 The Southern Pinwheel
• X-rays Discovered From Young Supernova Remnant Template:Webarchive (SN 1957D)
• Template:Cite web
• Messier 83 (Southern Pinwheel Galaxy) at Constellation Guide