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A series of fast rotating models at very low metallicity (Z=1e-8) was computed in order to explain the surface abundances observed at the surface of CEMP stars, in particular for nitrogen. The main results are the following: - Strong mixing…

Astrophysics · Physics 2008-11-26 R. Hirschi

Preliminary results of a new set of stellar evolution and nucleosynthesis calculations for massive stars are presented. These results were obtained with an extended reaction network up to Bi. The discussion focuses on the importance of…

Nuclear Theory · Physics 2017-08-23 T. Rauscher , R. D. Hoffman , A. Heger , S. E. Woosley

The evolutionary pathways of core-collapse supernova progenitors at the low-mass end of the spectrum are beset with major uncertainties. In recent years, a variety of evolutionary channels has been discovered in addition to the classical…

Solar and Stellar Astrophysics · Physics 2017-10-10 B. Müller , S. Wanajo , H. -Th. Janka , A. Heger , D. Gay , S. A. Sim

Massive stars are key sources of radiative, kinetic, and chemical feedback in the universe. Grids of massive star models computed by different groups each using their own codes, input physics choices and numerical approximations, however,…

Solar and Stellar Astrophysics · Physics 2015-06-23 Samuel Jones , Raphael Hirschi , Marco Pignatari , Alexander Heger , Cyril Georgy , Nobuya Nishimura , Chris Fryer , Falk Herwig

In the ONeMg cores of $8.8-9.5~{\rm M}_\odot$ stars, neon and oxygen burning is ignited off-center. Whether the neon-oxygen flame propagates to the center is critical to determine whether these stars undergo Fe core collapse or electron…

Solar and Stellar Astrophysics · Physics 2016-08-08 Samuel Jones , Raphael Hirschi , Ken'ichi Nomoto

We present computations of nucleosynthesis in low-mass red-giant-branch and asymptotic-giant-branch stars of Population I experiencing extended mixing. We adopt the updated version of the FRANEC evolutionary model, a new post-process code…

Solar and Stellar Astrophysics · Physics 2015-05-20 S. Palmerini , M. La Cognata , S. Cristallo , M. Busso

We briefly review the main problems related to the computation of the evolution of intermediate-mass stars: the treatment of turbulent convection and the occurrence of blue loops during the core He-burning phase. It is shown that, in order…

Astrophysics · Physics 2007-05-23 S. Cassisi

Evolved low-mass stars of a wide range of metallicity bear signatures of a non-standard mixing event in their surface abundances of Li, C, and N, and in their 12C/13C ratio. A Na overabundance has also been reported in some giants of open…

Astrophysics · Physics 2015-05-13 R. Smiljanic , R. Gauderon , P. North , B. Barbuy , C. Charbonnel , N. Mowlavi

Massive stars can explode in powerful supernovae (SNe) forming neutron stars but they may also collapse directly into black holes (BHs). Understanding and predicting their final fate is increasingly important, e.g, in the context of…

Solar and Stellar Astrophysics · Physics 2023-11-13 D. Temaj , F. R. N. Schneider , E. Laplace , D. Wei , Ph. Podsiadlowski

The production of the neutron-capture isotopes beyond iron that we observe today in the solar system is the result of the combined contribution of the r-process, the s- process and possibly the i-process. Low-mass AGB (2 < M/Msun < 3) and…

Structural and chemical changes during the AGB and post-AGB evolution are discussed with respect to two recent observational and theoretical findings. On the one hand, high-resolution infrared observations revealed details of the dynamical…

Astrophysics · Physics 2016-01-27 T. Bloecker , R. Osterbart , G. Weigelt , Y. Balega , A. Men'shchikov

Until recently synthetic AGB models had not taken into account the break-down of the core mass-luminosity (Mc-L) relation due to the occurrence of envelope burning in the most massive (M > 3.5 Msun) and luminous (Mbol > -6) stars. Marigo et…

Astrophysics · Physics 2007-05-23 Paola Marigo

Evidence suggests that the direct progenitor stars of some core-collapse supernovae (CCSNe) are luminous blue variables (LBVs), perhaps including some `superluminous supernovae' (SLSNe). We examine models in which massive stars gain mass…

Solar and Stellar Astrophysics · Physics 2015-06-23 Stephen Justham , Philipp Podsiadlowski , Jorick S. Vink

Nuclear reactions transform atomic nuclei inside stars. This is the process of stellar nucleosynthesis. The basic concepts of determining nuclear reaction rates inside stars are reviewed. How stars manage to burn their fuel so slowly most…

Solar and Stellar Astrophysics · Physics 2015-05-13 Alak Ray

Many disc-type post-asymptotic giant branch (post-AGB) stars are chemically peculiar, showing underabundances of refractory elements in their photospheres that correlate with condensation temperature. The aim of this paper is to investigate…

Solar and Stellar Astrophysics · Physics 2019-09-04 Glenn-Michael Oomen , Hans Van Winckel , Onno Pols , Gijs Nelemans

(abridged) We model the nucleosynthesis during the thermal pulse phase of a rotating, solar metallicity AGB star of 3M_sun. Rotationally induced mixing during the thermal pulses produces a layer (~2E-5M_sun) on top of the CO-core where…

Astrophysics · Physics 2009-11-07 Falk Herwig , Norbert Langer , Maria Lugaro

AGB stars are responsible for producing a variety of elements, including carbon, nitrogen, and the heavy elements produced in the slow neutron-capture process ($s$-elements). There are many uncertainties involved in modelling the evolution…

Solar and Stellar Astrophysics · Physics 2015-04-22 C. Abate , O. R. Pols , A. I. Karakas , R. G. Izzard

We introduce SNAPSHOT, a technique to systematically compute stellar structure models in hydrostatic and thermal equilibrium based on 3 structural properties - core mass $M_{\rm core}$, envelope mass $M_{\rm env}$ and core composition. This…

Solar and Stellar Astrophysics · Physics 2020-05-27 Eoin Farrell , Jose Groh , Georges Meynet , JJ Eldridge , Sylvia Ekström , Cyril Georgy

We present asymptotic giant branch (AGB) models of solar metallicity, to allow the interpretation of observations of Galactic AGB stars, whose distances should be soon available after the first release of the Gaia catalogue. We find an…

Solar and Stellar Astrophysics · Physics 2016-09-07 M. Di Criscienzo , P. Ventura , D. A. Garcia-Hernandez , F. Dell'Agli , M. Castellani , P. M. Marrese , S. Marinoni , G. Giuffrida , O. Zamora

We report the first spectroscopic identification of massive Galactic asymptotic giant branch (AGB) stars at the beginning of the thermal pulse (TP) phase. These stars are the most Li-rich massive AGBs found to date, super Li-rich AGBs with…

Solar and Stellar Astrophysics · Physics 2015-06-16 D. A. Garcia-Hernandez , O. Zamora , A. Yagüe , S. Uttenthaler , A. I. Karakas , M. Lugaro , P. Ventura , D. L. Lambert