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Article overview
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Evolution of ONeMg Core in Super-AGB Stars towards Electron-Capture Supernovae: Effects of Updated Electron-Capture Rate | | Shuai Zha
; Shing-Chi Leung
; Toshio Suzuki
; Ken'ichi Nomoto
; | | Date: |
9 Jul 2019 | | Abstract: | Stars with $sim 8-10~{M}_{odot}$ evolve to form a strongly degenerate ONeMg
core. When the core mass becomes close to the Chandrasekhar mass, the core
undergoes electron captures on $^{24}$Mg and $^{20}$Ne, which induce the
electron-capture supernova (ECSN). In order to clarify whether the ECSN leads
to a collapse or thermonuclear explosion, we calculate the evolution of an
$8.4~M_odot$ star from the main sequence until the oxygen ignition in the
ONeMg core. We apply the latest electron-capture rate on $^{20}$Ne including
the second forbidden transition, and investigate how the location of the oxygen
ignition (center or off-center) and the $Y_e$ distribution depend on the input
physics and the treatment of the semiconvection and convection. The central
density when the oxygen deflagration is initiated, $
ho_{
m c,def}$, can be
significantly higher than that of the oxygen ignition thanks to the convection,
and we estimate $log_{10}(
ho_{
m c,def}/mathrm{g~cm^{-3}})>10.10$. We
perform two-dimensional simulations of the flame propagation to examine how the
final fate of the ONeMg core depends on the $Y_e$ distribution and $
ho_{
m
c,def}$. We find that the deflagration starting from $log_{10}(
ho_{
m
c,def}/mathrm{g~cm^{-3}})>10.01 (< 10.01)$ leads to a collapse (thermonuclear
explosion). Since our estimate of $
ho_{
m c,def}$ exceeds this critical
value, the ONeMg core is likely to collapse, although further studies of the
convection and semiconvection before the deflagration are important. | | Source: | arXiv, 1907.4184 | | Services: | Forum | Review | PDF | Favorites | |
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