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The most massive Galactic globular cluster, Omega centauri, appears to have multiple populations. Its bluest main sequence and extended horizontal branch stars are suggested to have the common origin, that is, an extremely high helium…

Astrophysics · Physics 2009-11-13 Ena Choi , Sukyoung K. Yi

We reanalyze the problem of Li abundances in red giants of nearly solar metallicity. After an outline of the problems affecting our knowledge of the Li content in low-mass stars (M<3Mo), we discuss deep-mixing models for the RGB stages…

Solar and Stellar Astrophysics · Physics 2015-05-28 S. Palmerini , S. Cristallo , M. Busso , C. Abia , S. Uttenthaler , L. Gialanella , E. Maiorca

Binary post-asymptotic giant branch (post-AGB) stars are thought to be the products of a strong but poorly-understood interaction during the AGB phase. The aim of this contribution is to update the orbital elements of a sample of galactic…

Solar and Stellar Astrophysics · Physics 2018-12-05 Glenn-Michael Oomen , Hans Van Winckel , Onno Pols , Gijs Nelemans , Ana Escorza , Rajeev Manick , Devika Kamath , Christoffel Waelkens

New SiS multi-transition (sub-)millimetre line observations of a sample of AGB stars with varying photospheric C/O-ratios and mass-loss rates are presented. A combination of low- and high-energy lines are important in constraining the…

Astrophysics · Physics 2009-11-13 F. L. Schoeier , J. Bast , H. Olofsson , M. Lindqvist

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

AGB phases mark the end of the evolution for Low- and Intermediate-Mass Stars. Our understanding of the mechanisms through which they eject the envelope and our assessment of their contribution to the chemical evolution of Galaxies are…

Astrophysics · Physics 2011-07-21 R. Guandalini , M. Busso

Almost all stars in the 1-8 Msun range evolve through the Asymptotic Giant Branch (AGB), preplanetary nebula (PPN) and planetary nebula (PN) evolutionary phases. Most stars that leave the main sequence in a Hubble time will end their lives…

The aim of this work is to use full evolutionary models to derive observational constraints on the mass loss rate of the upper Asymptotic Giant Branch (AGB) stars. The observations used to constrain the models are the relative number of…

Astrophysics · Physics 2016-08-30 P. Ventura , F. D'Antona , I. Mazzitelli

Low- and intermediate-mass stars go through a period of intense mass-loss at the end of their lives in a phase known as the asymptotic giant branch (AGB). During the AGB a significant fraction of their initial mass is expelled in a stellar…

Solar and Stellar Astrophysics · Physics 2015-05-13 T. Khouri , L. B. F. M. Waters , A. de Koter , L. Decin , M. Min , B. L. de Vries , R. Lombaert , N. L. J. Cox

The literature is rich in analysis and results related to thermally pulsing-asymptotic giant branch (TP-AGB) stars, but the problem of the instabilities that arise and cause the divergence of models during the late stages of their evolution…

Solar and Stellar Astrophysics · Physics 2015-06-04 Herbert H. B. Lau , Pilar Gil-Pons , Carolyn Doherty , John Lattanzio

We investigate the uncertainty in surface abundances and yields of asymptotic giant branch (AGB) stars. We apply three different mass loss laws to a 1.5 solar mass star of metallicity Z=0.008 at the beginning of the thermally pulsing…

Astrophysics · Physics 2008-11-26 Richard J. Stancliffe , C. Simon Jeffery

Since 1996 we have known that the Galactic Center (GC) displays a core-like distribution of red giant branch (RGB) stars starting at ~ 10", which poses a theoretical problem, because the GC should have formed a segregated cusp of old stars.…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-17 Pau Amaro-Seoane , Xian Chen

We examine the flow from asymptotic giant branch (AGB) stars when along a small solid angle the optical depth due to dust is very large. We consider two types of flows. In the first, small cool spots are formed on the surface of slowly…

Astrophysics · Physics 2009-10-31 Noam Soker

We present a photometric and spectroscopic study of multiple populations along the asymptotic-giant branch (AGB) of the intermediate-metallicity globular clusters (GCs) NGC2808 and NGC6121 (M4). Chemical abundances of O, Na, Mg, Al, Si, Ca,…

Solar and Stellar Astrophysics · Physics 2019-10-09 A. F. Marino , A. P. Milone , D. Yong , G. Da Costa , M. Asplund , L. R. Bedin , H. Jerjen , D. Nardiello , G. Piotto , A. Renzini , M. Shetrone

Asymptotic giant branch stars are essential contributors to the near and mid-IR emission of intermediate age (0.1-1Gyr old) stellar populations. Detecting this light sets constraints on the star formation history in galaxies and,…

Astrophysics · Physics 2007-05-23 A. Lancon

I discuss the relationship between mass loss and nucleosynthesis on the Asymptotic Giant Branch (AGB). Because of thermal pulses and possibly other mixing processes, products of nucleosynthesis can be brought to the surface of AGB stars,…

Astrophysics · Physics 2015-05-13 Jacco Th. van Loon

The Thermally-Pulsating Asymptotic Giant Branch (TP-AGB) phase of stellar evolution has received attention only recently in galaxy evolution, but is now an important player in our understanding of how galaxies form and evolve. Because it is…

Cosmology and Nongalactic Astrophysics · Physics 2011-04-04 Claudia Maraston

Most carbon-enhanced metal-poor (CEMP) stars are thought to result from past mass transfer of He-burning material from an asymptotic giant branch (AGB) star to a low-mass companion star, which we now observe as a CEMP star. Because AGB…

Astrophysics of Galaxies · Physics 2015-06-11 Onno R. Pols , Robert G. Izzard , Richard J. Stancliffe , Evert Glebbeek

Intense mass loss through cool, low-velocity winds is a defining characteristic of low-to-intermediate mass stars during the asymptotic giant branch (AGB) evolutionary stage. Such winds return up ~80% of the initial stellar mass to the…

Solar and Stellar Astrophysics · Physics 2023-07-21 Lynn D. Matthews

Over two decades ago, a prominent, mysterious emission band peaking at ~20.1 micrometer was serendipitously detected in four preplanetary nebulae (PPNe; also known as "protoplanetary nebulae"). So far, this spectral feature, designated as…

Solar and Stellar Astrophysics · Physics 2016-07-06 Ajay Mishra , Aigen Li , B. W. Jiang