Journal Article

A single-degenerate channel for the progenitors of Type Ia supernovae with different metallicities

X. Meng, X. Chen and Z. Han

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 395, issue 4, pages 2103-2116
Published in print June 2009 | ISSN: 0035-8711
Published online May 2009 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2009.14636.x
A single-degenerate channel for the progenitors of Type Ia supernovae with different metallicities

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A single-degenerate channel for the progenitors of Type Ia supernovae (SNe Ia) is currently accepted, in which a carbon–oxygen white dwarf (CO WD) accretes hydrogen-rich material from its companion, increases its mass to the Chandrasekhar mass limit and then explodes as a SN Ia. Incorporating the prescription of Hachisu et al. for the accretion efficiency into Eggleton's stellar evolution code, and assuming that the prescription is valid for all metallicities, we performed binary stellar evolution calculations for more than 25 000 close WD binaries with metallicities Z= 0.06, 0.05, 0.04, 0.03, 0.02, 0.01, 0.004, 0.001, 0.0003 and 0.0001. For our calculations, the companions are assumed to be unevolved or slightly evolved stars (WD + MS). As a result, the initial parameter spaces for SNe Ia at various Z are presented in the orbital period–secondary mass (log Pi, Mi2) plane. Our study shows that both the initial mass of the secondary and the initial orbital period increase with metallicity. Thus, the minimum mass of the CO WD for SNe Ia decreases with metallicity Z. The difference in the minimum mass may be as large as 0.24 M for different Z.

Adopting the results above, we studied the birth rate of SNe Ia for various Z via a binary population synthesis approach. If a single starburst is assumed, SNe Ia occur systemically earlier and the peak value of the birth rate is larger for a high Z. The Galactic birth rate from the WD + MS channel is lower than (but comparable to) that inferred from observations. Our study indicates that supernovae like SN2002ic will not occur in extremely low-metallicity environments, if the delayed dynamical-instability model is appropriate.

Keywords: binaries: close; stars: evolution; supernovae: general; white dwarfs

Journal Article.  9535 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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