Proc. Neutrino Astrophysics - MPP Theory Group

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Indirect information can be obtained from the light curves and the spectra leading, however,
to an “inverse” problem as far as theoretical interpretations are concerned.
Theoretical Classification
The theoretical classification of supernovae is usually done according to the suspected progenitor
stars and the explosion mechanism, and it dates back to a classic paper of Fred Hoyle and
Willy Fowler in 1960 [4]. Based on very few observational facts available at that time, they
postulated that Type II supernovae are the consequence of an implosion of non-degenerate
stars, whereas Type I’s are the result of the ignition of nuclear fuel in degenerate stars, and
today this is still believed to be true in general, if “Type I’s” are substituted by “Type Ia’s”.
Figure 1: Theoretical classification scheme of supernovae according to their progenitors.
To be more specific, the present theoretical classification schemes based on progenitor
properties and the energetics of the explosion are given in Figs. 1 and 2, respectively. It is
now generally believed that Type II and Ib.c supernovae stem from collapsing massive stars
with and without hydrogen envelopes, respectively, and that SN Ia originate from explosions
of white dwarfs, although the way to explosion (accretion vs. merging of two white dwarfs) as
well as the mass of the white dwarf (Chandrasekhar vs. sub-Chandrasekhar mass) just prior
to the explosion are still heavily disputed (see Ref. [5] and references therein).
The classification with respect to the energetics is even more complex, and a variety of
possible models is available with no unique and well accepted answer. For example, in the
case of thermonuclear explosions, it is not even clear what the mode of propagation of the
burning front is, and observations supply poor constraints only. A (fast) deflagration wave
in a Chandrasekhar-mass white dwarf can explain the spectra and light curves of Type Ia’s,
but so can deflagrations changing into detonations at low densities with or without pulsations
(so-called delayed detonations), or even pure detonations in stars with low enough densities