Model atmospheres for SNe II during early stages
Abstract
The photospheres of type II supernovae during the coasting phase ( ~ 1 week to 1 month after outburst) are characterized by moderate temperatures (Teff ~ 7...12 Ö- 10^3K) , large radii (R ~ 10^13...10^15cm) , very low densities (p ~ 10^-13... 10^-16 gcm-3) and high expansions velocities (up to ~ 30000 km-1 in the outer layers). These properties lead to large geometrical extensions (i.e. the photons can travel a large fraction of the radius without being absorbed) and to electron scattering as the main source of opacity. Therefore these photospheres are very different from those of stars in hydrostatic equilibrium. In this review we first describe the input physics for models and essential numerical aspects of the model construction. In particular we stress the central role of an adequate treatment of the radiative transfer equation which should simultaneously take into account the sphericity, a high ratio of scattering to absorption, and relativistic effects. Subsequently we discuss details of the emergent spectra and their relevance for parameter determinations. Finally, model spectra are compared with observations of the bright supernovae SN 1979C and SN 1980 K, which seem to be more average examples of type II supernovae than SN 1987A, and possibilities for using these objects for extragalactic distance determinations are investigated.
- Publication:
-
Annales de Physique
- Pub Date:
- 1991
- DOI:
- 10.1051/anphys:01991001604039700
- Bibcode:
- 1991AnPh...16..397B
- Keywords:
-
- radiative transfer;
- stellar atmospheres;
- stellar models;
- stellar spectra;
- supernovae;
- stellar model atmospheres;
- effective temperatures;
- low density stellar photospheres;
- photospheric radii;
- early stage supernovae;
- spectral line profiles;
- emergent stellar spectra;
- stellar atmospheres opacity;
- spherical model atmosphere;
- scattering absorption ratio;
- supernovae colour colour diagrams;
- SNe II;
- Type II supernovae;
- coasting phase;
- expansion velocities;
- geometrical extensions;
- electron scattering;
- radiative transfer equation;
- relativistic effects;
- model spectra;
- SN 1979C;
- SN 1980 K;
- extragalactic distance determinations;
- 7 to 12 kK;
- 0.1 to 10 Tm;
- 30 Mm s;
- 7 to 30 d