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g-Mode Excitation During the Pre-explosive Simmering of Type Ia Supernovae

Piro, Anthony L. (2011) g-Mode Excitation During the Pre-explosive Simmering of Type Ia Supernovae. Astrophysical Journal Letters, 738 (1). Art. No. L5. ISSN 2041-8205.

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Prior to the explosive burning of a white dwarf (WD) that makes a Type Ia supernova (SN Ia), the star "simmers" for ~10^3 yr in a convecting, carbon-burning region. I estimate the excitation of g-modes by convection during this phase and explore their possible effect on the WD. As these modes propagate from the core of the WD toward its surface, their amplitudes grow with decreasing density. Once the modes reach nonlinear amplitudes, they break and deposit their energy into a shell of mass ~10^(–4) M_⊙. This raises the surface temperature by ≈4 × 10^8 K, which is sufficient to ignite a layer of helium, as is expected to exist for some SN Ia scenarios. This predominantly synthesizes ^(40)Ca, but some amount of ^(28)Si, ^(32)S, and ^(44)Ti may also be present. These ashes are expanded out with the subsequent explosion up to velocities of ~20, 000 km s^(–1), which may explain the high velocity features (HVFs) seen in many SNe Ia. The appearance of HVFs would therefore be a useful discriminant for determining between progenitors, since a flammable helium-rich layer will not be present for accretion from a C/O WD as in a merger scenario. I also discuss the implications of ^(44)Ti production.

Item Type:Article
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Piro, Anthony L.0000-0001-6806-0673
Additional Information:© 2011 The American Astronomical Society. Received 2011 May 3; accepted 2011 July 22; published 2011 August 8. I thank Philip Chang for some of the original conversations that inspired this research, and Lars Bildsten, Peter Goldreich, Fiona Harrison, Paolo Mazzali, Christian Ott, Eliot Quataert, Nevin Weinberg, and Stan Woosley for helpful feedback. This work was supported through NASA ATP grant NNX07AH06G, NSF grant AST-0855535, and by the Sherman Fairchild Foundation.
Funding AgencyGrant Number
Sherman Fairchild FoundationUNSPECIFIED
Subject Keywords:convection; stars: oscillations; supernovae: general; white dwarfs
Issue or Number:1
Classification Code:PACS: 97.60.Bw; 97.20.Rp; 97.10.Cv; 97.10.Sj
Record Number:CaltechAUTHORS:20110922-111543901
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Official Citation:g-mode Excitation During the Pre-explosive Simmering of Type Ia Supernovae Anthony L. Piro 2011 ApJ 738 L5
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:25399
Deposited By: Ruth Sustaita
Deposited On:22 Sep 2011 18:32
Last Modified:09 Mar 2020 13:19

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