2. Models and method of calculations
In our analysis we have studied two Chandrasekhar-mass models: the classical deflagration model W7 (Nomoto et al. 1984) and the delayed detonation model DD4 (Woosley & Weaver 1994b), as well as two sub-Chandrasekhar-mass models: helium detonation model 4 of Livne & Arnett (1995) (hereafter, LA4) and low-mass detonation model with low production (hereafter, WD065; Ruiz-Lapuente et al. 1993). Main parameters of these models are gathered in the Table 1, as well as the values of rise time and maximum UV fluxes in the standard IUE range (just as it is the most typical form of representation; e.g., Pun et al. 1995) and in the FUSE range. For definiteness the distance to a supernova is supposed to be 10 Mpc.
Table 1. Parameters of SN Ia models, rise time to the maximum of the UV light curves and UV fluxes at maximum light in FUSE and IUE ranges. Fluxes are calculated under the assumption that a supernova is at distance of 10 Mpc from the observer.
The method used here for light curve modeling is multi-energy group radiation hydrodynamics. Our code STELLA (Blinnikov & Bartunov 1993; Blinnikov et al. 1998) solves simultaneously hydrodynamic equations and time-dependent equations for the angular moments of intensity averaged over fixed frequency bands, using up to zones for the Lagrangean coordinate and up to 100 frequency bins (i.e., energy groups). This allows us to have a reasonably accurate representation of non-equilibrium continuum radiation in a self-consistent calculation when no additional estimates of thermalization depth are needed. Local Thermodynamic Equilibrium (LTE) for ionization and atomic level populations is assumed in our modeling. In the equation of state, LTE ionization and recombination are taken into account. The effect of line opacity is treated as an expansion opacity according to the prescription of Eastman & Pinto (1993) and Blinnikov (1996 , 1997).
© European Southern Observatory (ESO) 2000
Online publication: March 28, 2000