530 research outputs found
The single degenerate channel for the progenitors of type Ia supernovae
We have carried out a detailed study of one of the most popular evolutionary
channels for the production of Type Ia supernova (SN Ia) progenitors, the
semi-degenerate channel (CO+MS), where a carbon/oxygen (CO) white dwarf (WD)
accretes matter from an unevolved or slightly evolved non-degenerate star until
it reaches the Chandrasekhar mass limit. Employing Eggleton's stellar evolution
code and adopting the prescription of Hachisu et al. (1999) for the accretion
efficiency, we have carried out full binary evolution calculations for about
2300 close WD binary systems and mapped out the initial parameters in the
orbital period -- secondary mass (--) plane (for a range of WD masses)
which lead to a successful Type Ia supernova. We obtained accurate, analytical
fitting formulae to describe this parameter range which can be used for binary
population synthesis (BPS) studies. The contours in the -- plane differ
from those obtained by Hachisu et al. (1999) for low-mass CO WDs, which are
more common than massive CO WDs. We show that white dwarfs with a mass as low
as can accrete efficiently and reach the Chandrasekhar limit. We
have implemented these results in a BPS study to obtain the birthrates for SNe
Ia and the evolution of birthrates with time of SNe Ia for both a constant star
formation rate and a single star burst. The birthrates are somewhat lower than
(but comparable to) those inferred observationally.Comment: 10 pages, 14 figures, submitted to MNRA
The helium star donor channel for the progenitors of type Ia supernovae and their surviving companion stars
The nature of type Ia supernovae (SNe Ia) is still unclear. Employing
Eggleton's stellar evolution code with the optically thick wind assumption, we
systematically studied the He star donor channel of SNe Ia, in which a
carbon-oxygen white dwarf accretes material from a He main-sequence star or a
He subgiant to increase its mass to the Chandrasekhar mass. We mapped out the
initial parameters for producing SNe Ia in the orbital period--secondary mass
plane for various WD masses from this channel. According to a detailed binary
population synthesis approach, we find that this channel can produce SNe Ia
with short delay times (~100Myr) implied by recent observations. We obtained
many properties of the surviving companions of this channel after SN explosion,
which can be verified by future observations. We also find that the surviving
companions from the SN explosion scenario have a high spatial velocity
(>400km/s), which could be an alternative origin for hypervelocity stars
(HVSs), especially for HVSs such as US 708.Comment: 6 pages, 5 figures, to appear in the proceedings of the conference
"Binary Star Evolution: Mass Loss, Accretion, and Mergers" at Mykonos,
Greece, June 22-25, 201
- …