Astronomy and Astrophysics – Astrophysics
Scientific paper
2007-05-31
Astronomy and Astrophysics
Astrophysics
13 pages, 16 figures, submitted to ApJ, uses emulateapj
Scientific paper
10.1086/520872
We study the late evolution of solar metallicity stars in the transition region between white dwarf formation and core collapse. This includes the super-asymptotic giant branch (super-AGB, SAGB) stars, which have massive enough cores to ignite carbon burning and form an oxygen-neon (ONe) core. The most massive SAGB stars have cores that may grow to the Chandrasekhar mass because of continued shell-burning. Their cores collapse, triggering a so called electron capture supernovae (ECSN). From stellar evolution models we find that the initial mass range for SAGB evolution is 7.5 ... 9.25\msun. We perform calculations with three different stellar evolution codes to investigate the sensitivity of this mass range to some of the uncertainties in current stellar models. The mass range significantly depends on the treatment of semiconvective mixing and convective overshooting. To consider the effect of a large number of thermal pulses, as expected in SAGB stars, we construct synthetic SAGB models that include a semi-analytical treatment of dredge-up, hot-bottom burning, and thermal pulse properties. This synthetic model enables us to compute the evolution of the main properties of SAGB stars from the onset of thermal pulses until the core reaches the Chandrasekhar mass or is uncovered by the stellar wind. Thereby, we determine the stellar initial mass ranges that produce ONe-white dwarfs and electron-capture supernovae. The latter is found to be 9.0 ... 9.25\msun for our fiducial model, implying that electron-capture supernovae would constitute about 4% of all supernovae in the local universe. Our synthetic approach allows us to explore the uncertainty of this number imposed by uncertainties in the third dredge-up efficiency and ABG mass loss rate. We find for ECSNe a upper limit of ~20% of all supernovae (abridged).
Heger Alexander
Herwig Falk
Langer Norbert
Poelarends Arend Jan T.
No associations
LandOfFree
The Supernova Channel of Super-AGB Stars does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with The Supernova Channel of Super-AGB Stars, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The Supernova Channel of Super-AGB Stars will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-289152