NLTE Synthetic Spectra of Type Ia Supernovae

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Session 57 -- Planetary Nebulae/Supernovae/Ejecta
Display presentation, Thursday, 2, 1994, 9:20-6:30

[57.06] NLTE Synthetic Spectra of Type Ia Supernovae

Peter Nugent, E. Baron and David Branch (University of Oklahoma), Peter Hauschildt (Arizona State University)

An approximate lambda iteration is used to solve the fully relativistic radiation transport equation to all orders in v/c. The NLTE rate equations are solved for MgII, CaII and NaI using an extension of the method of Rybicki and Hummer 1991, simultaneously with the condition of radiative equilibrium. The Kurucz list of 3 million lines is used to select the approximately 300,000 strongest lines with the populations assumed to be in LTE. The model atmospheres are constructed assuming that the velocity profile is homologous and that the density profile follows either a power law or an exponential falloff. Both SNe 1981B and 1992A are fit from the UV through the optical near maximum light producing reasonable agreement with observations. We discuss the application of the expanding photosphere method to SNe Ia which gives a distance that is independent of those based on radioactive nickel decay and Cepheids variable stars.

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