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|Title:||Nebular spectra and abundance tomography of the Type Ia supernova SN 2011fe: a normal SN Ia with a stable Fe core||Authors:||Mazzali, P. A.
Filippenko, A. V.
Garnavich, P. M.
Clubb, K. I.
Pan, Y. -C.
Silverman, J. M.
|Issue Date:||2015||Journal:||MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY||Number:||450||Issue:||3||First Page:||2631||Abstract:||A series of optical and one near-infrared nebular spectra covering the first year of the Type Ia supernova SN 2011fe are presented and modelled. The density profile that proved best for the early optical/ultraviolet spectra, `ρ-11fe', was extended to lower velocities to include the regions that emit at nebular epochs. Model ρ-11fe is intermediate between the fast deflagration model W7 and a low-energy delayed-detonation. Good fits to the nebular spectra are obtained if the innermost ejecta are dominated by neutron-rich, stable Fe-group species, which contribute to cooling but not to heating. The correct thermal balance can thus be reached for the strongest [Fe II] and [Fe III] lines to be reproduced with the observed ratio. The <SUP>56</SUP>Ni mass thus obtained is ̃0.47 ± 0.05 M<SUB>☉</SUB>. The bulk of <SUP>56</SUP>Ni has an outermost velocity of ̃8500 km s<SUP>-1</SUP>. The mass of stable iron is ̃0.23 ± 0.03 M<SUB>☉</SUB>. Stable Ni has low abundance, ̃10<SUP>-2</SUP> M<SUB>☉</SUB>. This is sufficient to reproduce an observed emission line near 7400 Å. A sub-Chandrasekhar explosion model with mass 1.02 M<SUB>☉</SUB> and no central stable Fe does not reproduce the observed line ratios. A mock model where neutron-rich Fe-group species are located above <SUP>56</SUP>Ni following recent suggestions is also shown to yield spectra that are less compatible with the observations. The densities and abundances in the inner layers obtained from the nebular analysis, combined with those of the outer layers previously obtained, are used to compute a synthetic bolometric light curve, which compares favourably with the light curve of SN 2011fe.||Acknowledgments:||We would like to thank S. Bradley Cenko, Isaac Shivvers, Ori Fox, Pat Kelly, and Daniel Cohen for assistance with the observations. MS acknowledges support from the Royal Society and EU/FP7-ERC grant number . AVF is grateful for support from the Richard Rhoda Goldman Fund, the Christopher R. Redlich Fund, the TABASGO Foundation, and NSF grant AST–1211916. SH is supported by the German Ministry of Education and Research (BMBF) via a Minerva ARCHES award. BS is a Hubble, Carnegie-Princeton Fellow, and supported by NASA through Hubble Fellowship grant HF-51348.001, awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS 5-26555. JMS is supported by an NSF Astronomy and Astrophysics Postdoctoral Fellowship under award AST-1302771. SB is partially supported by the PRIN-INAF 2014 with the project ‘Transient Universe: unveiling new types of stellar explosions with PESSTO’. The William Herschel Telescope is operated on the island of La Palma by the Isaac Newton Group in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias; we are grateful to the staff there, as well as at Lick Observatory, for their excellent assistance.||URI:||http://hdl.handle.net/20.500.12386/24123||URL:||https://academic.oup.com/mnras/article/450/3/2631/1063091||ISSN:||0035-8711||DOI:||10.1093/mnras/stv761||Bibcode ADS:||2015MNRAS.450.2631M||Fulltext:||open|
|Appears in Collections:||1.01 Articoli in rivista|
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