Supernovae as astrophysical objects

European Southern Observatory Karl-Schwarzfchild-Strasse 2, D-85748 Garching Germany 

Abstract Supernovae are a prominent component of modern astrophysics. They are responsible for a major part of the chemical enrichment in the universe and the main recycling mechanism in galaxies. The physics of these explosions is fairly well, although not completely, understood. 

This article reviews the current understanding of the supernova explosions. After a brief historical introduction the two main classes of supemovae are described starting from the classification scheme currently employed. The different energy inputs for supemovae are presented. Despite their rather different energy sources supernovae from different types reach very similar luminosities. A notable exception to this are the Gamma-Ray Bursts, which are several orders of magnitude more energetic. The characteristics of each supernova type are presented. 

Keywords Supernovae explosion physics chemical enrichment 

It was Walter Baade who made the connection between the historical supernovae and the observed emission nebulae at their positions, thus identifying the remnants of the explosions. The most prominent object is of course the Crab Nebular (Messier 1), the leftover from the supernova in 1054 Baade 1942 May all Oort 1942. With extensive observations of bright supernovae Minkowski Minkowski 1941 introduced two subclasses. Zwicky Zwicky 1965 refined the classification scheme for supemovae further. However, for several decades only two main classes were maintained until in the early eighties it became clear that at least one further subclass needs to be added. 

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Since the recognition of supernovae as a separate class of astrophysical objects they have been proposed and used to measure the distance scale and the geometry of the universe. 

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