M 83

M83 was classified as intermediate between normal and barred spiral galaxies by G. de Vaucouleurs, in his classification this is SAB(s)c. It is magnificient in our image, has very well defined spiral arms and displays a very dynamic appearance, appealing by the red and blue knots tracing the arms. The red knots are apparently diffuse gaseous nebulae in which star formation is just taking place, and which are excited to shine by its very hot young stars. The blue regions represent young stellar populations which have formed shortly (i.e., some million or some dozens of million years ago). The dust lanes may be traced well into the central region to the nucleus which has only 20" diameter.

David Malin, in his older publications, always gave a distance of about 25 million light years, as he does in his book A View of the Universe in chapter 4, while in his Galaxis chapter 8, he joins the lot of those claiming a distance of about 10 million light years, and gives an argument, namely that the brightest stars can be viewed as individuals over this distance. M83 recedes at 337 km/sec, implying a bit larger distance from Hubble's law.

This galaxy is sometimes called the "Southern Piwheel". It forms a small physical group with the peculiar radio galaxy Centaurus A (NGC 5128) and the unusual galaxy NGC 5253 in Centaurus.

Five or six supernovae were reported in M83 up to now, more than in any other Messier galaxy: 1923A was observed by C.O. Lampland at Lowell Observatory at mag 14. 1945B appeared on Jul 13, 1945 and reached mag 14.2 according to some source, but is not mentioned by Kenneth Glyn Jones. 1950B was observed by G. Haro and reached mag 14.5 in its maximum, 1957D was discovered by H.S. Gates on December 13, 1957 and reached only mag 15.0, it was about 3' NNE of the nucleus. Supernova 1968L was discovered visually by amateur astronomer Jack C. Bennett of Pretoria, South Africa, when sweeping for comets; this was a type I, located 5" preceding the nucleus and reached mag 11 to 12. 1983N appeared on July 3, 1983 and became as bright as 12.5 mag.

For years, M83 had been the galaxy with most discovered supernovae, but recently NGC 6946 came up with the same number of 6, or even one more if 1945B should be an error.

Right ascension	13 : 34.3 (hours : minutes)
Declination	-29 : 37 (degrees : minutes)
Distance	8000.0 (light-years*10^3)
Visual magnitude	10.1