Abundance stratification in Type Ia supernovae - IV. The luminous, peculiar SN 1991T

作者：Sasdelli Michele^*; Mazzali P A; Pian E; Nomoto K; Hachinger S; Cappellaro E; Benetti S

来源：Monthly Notices of the Royal Astronomical Society, 2014, 445(1): 711-725.

DOI：10.1093/mnras/stu1777

• line: formation
• line: identification
• radiative transfer
• stars: abundances
• supernovae: general
• supernovae: individual: SN 1991T

The abundance distribution of the elements in the ejecta of the peculiar, luminous Type Ia supernova (SN Ia) 1991T is obtained modelling spectra from before maximum light until a year after the explosion, with the method of %26apos;Abundance Tomography%26apos;. SN 1991T is different from other slowly declining SNe Ia (e. g. SN 1999ee) in having a weaker Si II 6355 line and strong features of iron group elements before maximum. The distance to the SN is investigated along with the abundances and the density profile. The ionization transition that happens around maximum sets a strict upper limit on the luminosity. Both W7 and the WDD3 delayed detonation models are tested. WDD3 is found to provide marginally better fits. In this model the core of the ejecta is dominated by stable Fe with a mass of about 0.15M(circle dot), as in most SNe Ia. The layer above is mainly Ni-56 up to v similar to 10 000 km s(-1) (approximate to 0.78M(circle dot)). A significant amount of Ni-56 (similar to 3 per cent) is located in the outer layers. A narrow layer between 10 000 km s(-1) and similar to 12 000 km s(-1) is dominated by intermediate-mass elements (IME), similar to 0.18M(circle dot). This is small for a SN Ia. The high luminosity and the consequently high ionization, and the high Ni-56 abundance at high velocities, explain the peculiar early-time spectra of SN 1991T. The outer part is mainly of oxygen, similar to 0.3M(circle dot). Carbon lines are never detected, yielding an upper limit of 0.01M(circle dot) for C. The abundances obtained with the W7 density model are qualitatively similar to those of the WDD3 model. Different elements are stratified with moderate mixing, resembling a delayed detonation.

• 出版日期2014-11-21