CIRCUMSTELLAR Na I AND Ca II LINES OF TYPE Ia SUPERNOVAE IN SYMBIOTIC SCENARIO

Formation of circumstellar resonant lines of Na I and Ca II in type Ia supernovae is studied for the case, when supernova explodes in a binary system with a red giant. The model suggests a spherically-symmetric wind and takes into account ionization and heating of the wind by X-rays from the shock wave and by gamma-quanta of Ni radioactive decay. For the wind density typical of the red giant the expected optical depth of the wind in Na I lines turnes out low (τ < 10) to detect the absorption. For the same wind densities the predicted optical depth of Ca II 3934 Å is sufficient for the detection (τ > 0.1). I conclude that the absorption lines detected in SN 2006X cannot form in the red giant wind; they are rather related to clouds at distances larger than the dust evaporation radius (r > 10 cm). From the absence in SN 2006X of Ca II absorption lines not related with the similar Na I components I derive the upper limit of the mass loss rate by the wind with velocity u: Ṁ < 10(u/10 km s) M⊙ yr .