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Session 90 - Supernovae, Supernovae Remnants and Planetary Nebulae.
Oral session, Wednesday, January 17
Salon del Rey Central, Hilton
Type II supernovae provide an excellent opportunity to probe various properties of the universe. Their relative physical simplicity allows us to calculate model spectra by invoking well understood physics.
We perform a semi-analytic calculation of the continuum spectra of type II supernovae. This is an extension of the approximate radiative transfer analysis of Hershkowitz, Linder and Wagoner to a more general class of model atmospheres, using a simple fit to the continuum opacity produced by lines. The atmosphere is characterized by an effective temperature, a radial power-law dependence of the density of hydrogen, and less strongly by the heavy element abundance and velocity gradient. We match asymptotic expressions for the spectral energy density at the photosphere, whose location at each frequency is determined by a first order calculation of the deviation of the mean intensity from the Planck function. The emergent spectral luminosity then assumes the form of a diluted blackbody, and the major result is the dependence of this frequency dependent dilution factor upon the temperature and radius of the photosphere, as well as the power-law index of the hydrogen density distribution.
These results are used to determine the power law indices for several supernovae. We compare our dilution factors to those of Schmidt, Kirshner and Eastman. The comparison of the dilution factors allows us to estimate the distances we obtain compared to distances obtained by SKE.
Program listing for Wednesday