Burning regimes for thermonuclear supernovae and cosmological applicationsof SNe Ia

The method of multigroup radiation hydrodynamics is used to compute light c urves for thermonuclear supernovae. Opacities are computed by taking into a ccount spectral lines and expansion. UBVI fluxes are predicted. Our compute d times of brightness rise to a maximum in B and V have been found to agree with observations better than those of other authors. The validity of our results is justified physically. The nuclear burning regime is shown to aff ect significantly the slope of the light curve in B and, to a slightly less er extent, in V. If the prevailing burning regime during supernova explosio ns changed with age of the Universe, then the conclusion about a positive c osmological constant A drawn from observations of Type Ia supernovae may pr ove to be wrong. (C) 2000 MAIK "Nauka/Interperiodica".