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The evolution and lifetimes of thermally pulsating asymptotic giant branch (TP-AGB) stars suffer from significant uncertainties. We present a detailed framework for constraining model luminosity functions of TP-AGB stars using resolved…

CEMP-s stars are very metal-poor stars with enhanced abundances of carbon and s-process elements. They form a significant proportion of the very metal-poor stars in the Galactic halo and are mostly observed in binary systems. This suggests…

Solar and Stellar Astrophysics · Physics 2014-03-05 Carlo Abate , Onno R. Pols , Robert G. Izzard , Amanda I. Karakas

Lithium and zirconium abundances (the latter taken as representative for s-process enrichment) are determined for a large sample of massive Galactic O-rich AGB stars, for which high resolution optical spectroscopy has been obtained…

Astrophysics · Physics 2009-11-11 D. A. Garcia-Hernandez , P. Garcia-Lario , B. Plez , A. Manchado , F. D'Antona , J. Lub , H. Habing

We aim to (1) set up simple and general analytical expressions to estimate mass-loss rates of evolved stars, and (2) from those calculate estimates for the mass-loss rates of asymptotic giant branch (AGB), red supergiant (RSG), and yellow…

Solar and Stellar Astrophysics · Physics 2015-05-19 E. De Beck , L. Decin , A. de Koter , K. Justtanont , T. Verhoelst , F. Kemper , K. M. M. Menten

We explore the final fates of massive intermediate-mass stars by computing detailed stellar models from the zero age main sequence until near the end of the thermally pulsing phase. These super-AGB and massive AGB star models are in the…

Solar and Stellar Astrophysics · Physics 2015-06-23 Carolyn L. Doherty , Pilar Gil-Pons , Lionel Siess , John C. Lattanzio , Herbert H. B. Lau

We study the effects of a reduced mass-loss rate on the evolution of low metallicity Jsolated stars, following our earlier classification for angular momentum (J) isolated stars. By using the stellar evolution code MESA we study the…

Solar and Stellar Astrophysics · Physics 2018-08-17 Efrat Sabach

We have made a parametric study of s-process nucleosynthesis in the metal poor ([Fe/H]=-2.7) stars LP625-44 and LP706-7. We find that a high neutron exposure and a small overlap factor are necessary to fit the abundance pattern observed in…

We report on an investigation into stellar evolution and nucleosynthesis in the low and extremely low metallicity regime, including models of stars with a pure Big Bang composition (i.e. Z=0). The metallicity range of the extremely metal…

Astrophysics · Physics 2008-11-26 Simon W. Campbell , John C. Lattanzio

Using the minimal extension of Standard Model taking into account the charge radius and the anapole moments of neutrino, we have derived analytic expressions for the stellar energy loss rates due to the production of the neutrino pair…

High Energy Physics - Phenomenology · Physics 2023-03-08 Coskun Aydin

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

The hydrogen-deficiency in extremely hot post-AGB stars of spectral class PG1159 is probably caused by a (very) late helium-shell flash or a AGB final thermal pulse that consumes the hydrogen envelope, exposing the usually-hidden intershell…

Solar and Stellar Astrophysics · Physics 2015-05-14 K. Werner

We present here the application of a model for a mass circulation mechanism in between the H-burning shell and the base of the convective envelope of low mass AGB stars, aimed at studying the isotopic composition of those presolar grains…

Solar and Stellar Astrophysics · Physics 2017-02-21 Sara Palmerini , Oscar Trippella , Maurizio Busso

Dust formation and resulting mass loss around Asymptotic Giant Branch (AGB) stars with initial metallicity in the range of $0 \leq Z_{\rm ini} \leq 10^{-4}$ and initial mass $2\leq M_{\rm ini}/M_{\odot} \leq 5$ are explored by the…

Solar and Stellar Astrophysics · Physics 2017-01-18 Shohei Tashibu , Yuki Yasuda , Takashi Kozasa

We examine the generation of gravity waves by the surface convection zone of low-mass main sequence stars with solar metallicity. It is found that the total momentum luminosity in waves rises with stellar mass, up to the quasi-disappearance…

Astrophysics · Physics 2010-11-19 Suzanne Talon , Corinne Charbonnel

NLTE spectral analyses of high-gravity central stars by means of state-of-the-art model atmosphere techniques provide information about the precursor AGB stars. The hydrogen-deficient post-AGB stars allow investigations on the intershell…

Astrophysics · Physics 2009-11-11 Thomas Rauch

Stars with masses above 1.6 solar masses generally possess convective cores and radiative envelopes, which allows the propagation of outward-travelling internal gravity waves. We have studied the generation and propagation of IGWs in such…

Solar and Stellar Astrophysics · Physics 2023-06-21 R. P. Ratnasingam , T. M. Rogers , S. Chowdhury , G. Handler , R. Vanon , A. Varghese , P. V. F. Edelmann

We predict mass-loss rates for the late evolutionary phases of low-mass stars, with special emphasis on the consequences for the morphology of the Horizontal Branch (HB). We show that the computed rates, as predicted by the most plausible…

Astrophysics · Physics 2015-06-24 Jorick S. Vink , Santi Cassisi

In the Halo21 absorption modeling challenge we generated synthetic absorption spectra of the circumgalactic medium (CGM), and attempted to estimate the metallicity, temperature, and density (Z, T, and nH) of the underlying gas using…

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…

Solar and Stellar Astrophysics · Physics 2021-11-17 Amanda Karakas , Giulia Cinquegrana , Meridith Joyce

Strong mass loss off stars at the tip of the asymptotic giant branch (AGB) profoundly affects properties of these stars and their surroundings, including the subsequent planetary nebula (PN) stage. With this study we wanted to determine…