TYPE IA SUPERNOVAE - THEIR ORIGIN AND POSSIBLE APPLICATIONS IN COSMOLOGY

Spectroscopic and photometric evidence indicates that Type la supernov ae (SNe Ia) are the thermonuclear explosions of accreting white dwarfs . However, the progenitor binary systems and hydrodynamical models for SNe Ia are still controversial, The relatively uniform light curves a nd spectral evolution of SNe Ia have led to their use as a standard ca ndle for determining cosmological parameters, such as the Hubble const ant, the density parameter, and the cosmological constant, Recent prog ress includes the calibration of the absolute maximum brightness of SN e Ia with the Hubble Space Telescope, the reduction of the dispersion in the Hubble diagram through the use of the relation between the ligh t curve shape and the maximum brightness of SNe Ia, and the discovery of many SNe Ia with high red shifts.