Messier 83 Explained

Messier 83
Type:	SAB(s)c
Dist Ly:	4.5Mpc
Appmag V:	7.6^[1]
Size:	36.24kpc (diameter; 26.0 mag/arcsec^2 B-band isophote)

Messier 83 or M83, also known as the Southern Pinwheel Galaxy and NGC 5236, is a barred spiral galaxy 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. Charles Messier added it to his catalogue of nebulous objects (now known as the Messier Catalogue) in March 1781.

It is one of the closest and brightest barred spiral galaxies in the sky, and is visible with binoculars. It has an isophotal diameter at about 36.24kpc. Its nickname of the Southern Pinwheel derives from its resemblance to the Pinwheel Galaxy (M101).

Characteristics

M83 is a massive, grand design spiral galaxy. Its morphological classification in the De Vaucouleurs system is SAB(s)c, 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. The peculiar dwarf galaxy NGC 5253 lies near M83, and the two likely interacted within the last billion years resulting in starburst activity in their central regions.

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

Supernovae

Six supernovae have been observed in M83:

• SN 1923A (type unknown, mag. 14) was discovered by Carl Otto Lampland on 5 May 1923.^{[2] [3]}
• SN 1945B (type unknown, mag. 14.2) was discovered by William Liller on 13 July 1945.^{[4] [5]}
• SN 1950B (type unknown, mag. 14.5) was discovered by Guillermo Haro on 15 March 1950.^[6]
• SN 1957D (type unknown, mag. 15) was discovered by H. S. Gates on 28 December 1957.^{[7] [8] [9]}
• SN 1968L (type II-P, mag. 11.9)^{[10] [11]} was discovered by J. C. Bennett on 17 July 1968.^[12]
• SN 1983N (type Ia, mag. 11.9) was discovered by Robert Evans from Australia on July 3, 1983.^[13] On July 6, 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 July 17, achieving an apparent visual magnitude of 11.54. Although identified as type I, the spectrum was considered peculiar. A year after the explosion, about 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. SN 1983N became the modern prototype of a hydrogen deficient type Ib supernova, with the progenitor being inferred as a Wolf–Rayet star.

Environment

M83 is at the center of one of two subgroups within the Centaurus A/M83 Group, a nearby galaxy group. Centaurus A is at the center of the other subgroup. These are sometimes identified as one group, and sometimes as two. 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.

See also

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

External links

• • 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 (SN 1957D)
• Web site: Bauer. Amanda. M83 – Southern Pinwheel Galaxy. Deep Sky Videos. Brady Haran. Haese, Paul.
• Messier 83 (Southern Pinwheel Galaxy) at Constellation Guide

Notes and References

1. Web site: Messier 83. 30 April 2022. SEDS Messier Catalog.
2. Web site: Transient Name Server . SN1923A . . 2 December 2024.
3. 1923PASP...35..166L . Note on a Nova . Lampland . C. O. . Publications of the Astronomical Society of the Pacific . 1923 . 35 . 205 . 166 . 10.1086/123293.
4. Web site: Transient Name Server . SN1945B . . 2 December 2024.
5. 1990IAUC.5091....2L . Supernova 1945B in NGC 5236 . Liller . W. . International Astronomical Union Circular . 1990 . 5091 . 2.
6. Web site: Transient Name Server . SN1950B . . 2 December 2024.
7. Web site: Transient Name Server . SN1957D . . 2 December 2024.
8. Web site: Circular No. 1643 . Hansen . Julie M. Vinter . 7 March 1958 . Central Bureau for Astronomical Telegrams . Observatory Copenhagen . 30 November 2024.
9. 1959LAstr..73..453B . Les cinq supernovæ découvertes depuis 1957 . Bertaud . Ch. . L'Astronomie . 1959 . 73 . 453.
10. 1996AJ....111.2017V. Supernovae and Massive Star Formation Regions. Van Dyk. Schuyler D.. Hamuy. Mario. Filippenko. Alexei V.. The Astronomical Journal. 1996. 111. 2017. 10.1086/117937.
11. Web site: Transient Name Server . SN1968L . . 2 December 2024.
12. Web site: Circular No. 2085 . Marsden . Brian G. . 17 July 1968 . Central Bureau for Astronomical Telegrams . Smithsonian Astrophysical Observatory . 2 December 2024.
13. Web site: Transient Name Server . SN1983N . . 2 December 2024.