Abundance stratification in Type Ia supernovae – II. The rapidly declining, spectroscopically normal SN 2004eo |
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| Authors: | Paolo A Mazzali D N Sauer A Pastorello S Benetti W Hillebrandt |
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| Institution: | Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Str. 1, 85748 Garching, Germany;Istituto Naz. di Astrofisica-Oss. Astron., Via Tiepolo, 11, 34131 Triste, Italy;Research Centre for the Early Universe and Dept. of Astronomy, School of Science, University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan;Kavli Institute for Theoretical Physics, University of California, Santa Barbara, CA 93106-4030, USA;Astrophysics Research Centre, Queen's University, Belfast BT7 1NN;Istituto Naz. di Astrofisica-Oss. Astron., vicolo dell'Osservatorio, 5, 35122 Padova, Italy |
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| Abstract: | The variation in properties of Type Ia supernovae, the thermonuclear explosions of Chandrasekhar-mass carbon–oxygen white dwarfs, is caused by different nucleosynthetic outcomes of these explosions, which can be traced from the distribution of abundances in the ejecta. The composition stratification of the spectroscopically normal but rapidly declining SN 2004eo is studied by performing spectrum synthesis of a time-series of spectra obtained before and after maximum, and of one nebular spectrum obtained about eight months later. Early-time spectra indicate that the outer ejecta are dominated by oxygen and silicon, and contain other intermediate-mass elements, implying that the outer part of the star was subject only to partial burning. In the inner part, nuclear statistical equilibrium (NSE) material dominates, but the production of 56Ni was limited to ～0.43 ± 0.05 M⊙ . An innermost zone containing ～0.25 M⊙ of stable Fe-group material is also present. The relatively small amount of NSE material synthesized by SN 2004eo explains both the dimness and the rapidly evolving light curve of this supernova. |
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| Keywords: | radiative transfer supernovae: general supernovae: individual: SN 2004eo |
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