The circumstellar matter in pre-supernovae of type Ia.
Abstract
The pre-supernova winds of type I SN are very difficult to detect: they are of low mass, rather slow (hundreds of km/s) and almost immediately swept by the SN envelope expanding at very high speed. No Type Ia supernova has ever been observed in radio. Nevertheless the SNe 1981B and 1990M give evidence of the existence of a circumstellar shell, which is revealed by hydrogen lines in the premaximum spectra. Those are compared with the superwind structures observed in type II SNe. Judging from the expansion velocity of the SN envelope, the wind formed structures under consideration are situated at a radius from the explosion centre of 1014-1015 cm. The time of ejection prior to the explosion event can be estimated as 5 x 107 s for SN 1990M. Such rather small distances and short periods of time for the formation of the regular structures imply the presence of high initial gradients of density and velocity in the wind matter. Thus an extraordinary activity of the precursor can be suspected. The possible mechanisms of recurrent ejections of matter in pre-supernovae binary systems are discussed.
- Publication:
-
Revista Mexicana de Astronomia y Astrofisica Conference Series
- Pub Date:
- December 1996
- Bibcode:
- 1996RMxAC...5...27T
- Keywords:
-
- Stellar Envelopes;
- Supernovae;
- Stellar Winds;
- Binary Data;
- Mass;
- Radii;
- Hydrogen;
- High Speed;
- Explosions;
- Estimating;
- Ejection;
- Distance;
- Astrophysics