ASTRO SEMINAR

The speaker will be Dr. Marcella Contini

Place: Holcblat Hall

Time: Wednesday, 06/Nov/2002, 14:00

Title: AG Pegasi: A New Model for Symbiotic Novae

Abstract

The analysis of the UV-optical spectra observed from AG Pegasi at different phases between 1981 and 1996 reveals that at least three nebulae contribute to the observed spectra :
  1. The nebula between the stars, downstream of the shock created by collision of the winds, which propagates in reverse towards the WD,
  2. The nebula downstream of the shock expanding in the outskirts of the giant atmosphere, and
  3. The shock propagating outwards the binary system, that is not reached by the hot source radiation.
It is found that the contribution to the different lines changes with the viewing angle of the system. The relatively low preshock density and magnetic field adopted in the modelling of the expanding shocks indicate that they are merging with the ISM, thus explaining the slow decline of AG Pegasi.