Related papers: On Carbon Burning in Super Asymptotic Giant Branch…
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…
We investigate the behaviour of asymptotic giant branch (AGB) stars between metallicities Z = 10-4 and Z = 10-8 . We determine which stars undergo an episode of flash-driven mixing, where protons are ingested into the intershell convection…
We present new stellar evolutionary sequences of very metal-rich stars evolved with the Monash Stellar Structure code and with MESA. The Monash models include masses of $1-8M_{\odot}$ with metallicities $Z=0.04$ to $Z=0.1$ and are evolved…
Recent studies on direct imaging of Type II core-collapse supernova progenitors indicate a possible threshold around $M_{\rm ZAMS}\sim 16-20$ M$_\odot$, where red supergiants with larger birth masses do not appear to result in supernova…
The evolution of a zero metallicity 9 M_s star is computed, analyzed and compared with that of a solar metallicity star of identical ZAMS mass. Our computations range from the main sequence until the formation of a massive oxygen-neon white…
We present a new grid of stellar model calculations for stars on the Asymptotic Giant Branch between 1.0 and 6.0 M_sun. Our grid consists of 5 chemical mixtures between Z=0.0005 and Z=0.04, with both solar-like and $\alpha$-element enhanced…
We calculated models of massive AGB stars with a self-consistent coupling of time-dependent mixing and nuclear burning for 30 isotopes and 74 reactions. Overshoot with an exponentially declining velocity field was considered and applied…
Based on evolutionary computations of 90 stellar models, we have analysed the impact of initial composition and core overshooting on the post-He-burning evolution and the associated nucleosynthesis of Super-AGB stars, pointing particular…
We describe our first attempt at modelling nucleosynthesis in massive AGB stars which have undergone core carbon burning, the super-AGB stars. We fit a synthetic model to detailed stellar evolution models in the mass range 9<=M/Msun<=11.5…
The circumstellar envelopes (CSEs) of asymptotic giant branch (AGB) stars harbour a rich variety of molecules and are sites of complex chemistry. Our current understanding of the circumstellar chemical processes of carbon-rich AGB stars is…
In the 90's, theoretical studies motivated the use of the asymptotic-giant branch bump (AGBb) as a standard candle given the weak dependence between its luminosity and stellar metallicity. Because of the small size of observed…
We give a brief review on the properties of asymptotic giant branch models with overshoot. Then we describe new model calculations with overshoot. Initial masses are ranging from 1 to 3Msun and metallicities are Z=0.02, 0.01 and 0.001.…
We discuss the characteristics of known extremely metal-poor (EMP) stars in the Galaxy using the Stellar Abundances for Galactic Archaeology (SAGA) database (Suda et al. 2008, PASJ, 60, 1159).The analyses of carbon-enhanced stars in our…
We present the first detailed three-dimensional hydrodynamic implicit large eddy simulations of turbulent convection for carbon burning. The simulations start with an initial radial profile mapped from a carbon burning shell within a 15…
The basic mechanism responsible for the widespread condensation of MgS in the outflows from carbon rich stars on the tip of the AGB is discussed with the aim of developing a condensation model that can be applied in model calculations of…
We investigate the physical and chemical evolution of population II stars with initial masses in the range 6.5-8 Msun, which undergo an off centre carbon ignition under partially degenerate conditions, followed by a series of thermal…
We present submillimeter observations of rotational transitions of carbon monoxide from J = 2 -> 1 up to 7 -> 6 for a sample of Asymptotic Giant Branch stars and red supergiants. It is the first time that the high transitions J = 6 -> 5 and…
We compute and analyze the evolution of primordial stars of masses at the ZAMS between 5 M_sun and 10 M_sun, with and without overshooting. Our main goals are to determine the nature of the remnants of massive intermediate-mass primordial…
The influence of extended convective mixing (overshoot) on asymptotic giant branch stellar evolution is investigated in detail. The extended mixing is treated time-dependently, and the efficiency declines exponentially with the geometric…
We have investigated the role of the convective overshooting on the production of s-nuclei during core He-burning phase in stellar models with different initial mass and metallicity ($15 \leq M_{ZAMS}/M_{\odot} \leq 25$; $10^{-4} \leq Z…