Evolution of the number of accreting white dwarfs with shell nuclear burning and the SNe Ia rate |
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Authors: | L R Yungelson |
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Institution: | (1) Devon, UK |
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Abstract: | We analyze the time evolution of the number of accreting white dwarfs with surface shell hydrogen burning in semidetached
and detached binaries. We consider the case where continuous star formation with a constant rate takes place in a stellar
system over 1010 Gyr and the case of a starburst in which the same mass of stars is formed over 109 Gyr. The evolution of the number of white dwarfs is compared with the evolution of the rate of events that are usually considered
as SNe Ia and/or accretion-induced collapses, i.e., the accumulation of a Chandrasekhar mass by white dwarfs or the merger
of white dwarf pairs with a total mass greater than or equal to the Chandrasekhar one. In stellar systems with a starburst,
the supersoft X-ray sources observed at t = 1010 yr are most likely not the progenitors of SNe Ia. The same is true for a significant fraction of the sources in systems with
a constant star formation rate. In both cases, the merger of white dwarfs is the dominant mechanism of SNe Ia. In symbiotic
binaries, accreting CO dwarfs do not accumulate enough mass for an SNe Ia explosion, while ONeMg dwarfs finish their evolution
by an accretion-induce collapse with the formation of a neutron star. |
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Keywords: | |
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