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The impact of AGB stars on the chemical evolution of globular clusters
Jehin, Emmanuel; Magain, Pierre; Neuforge, Corinne et al.
1998In Asymptotic Giant Branch Stars
 

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Abstract :
[en] We have analyzed high resolution and high signal-to-noise spectra of about 20 metal-poor stars. The correlations between the relative abundances of 16 elements have been studied, with a special emphasis on the neutron-capture ones. This analysis reveals the existence of two sub-populations of field halo stars, namely Pop IIa and Pop IIb. They differ by the behaviour of the s-process elements versus the alpha and r-process elements. We present a scenario for the formation of these stars, which closely relates the origin of field halo stars to the evolution of globular clusters. According to this scenario, the two sub-populations originate from two different stages in the globular cluster's chemical evolution. In the first stage, the massive stars of the globular cluster's first stellar generation evolve, ending their lives as supernovae and ejecting alpha-elements and r-process elements into the interstellar medium. A second generation of stars forms out of this enriched ISM. In the second stage, the intermediate mass stars reach the end of the main sequence and the AGB stage, ejecting s-elements into the ISM through stellar winds or superwinds events. The matter released in the ISM by the AGB stars will be accreted by the lower-mass stars, enriching those stars in s-elements and accounting for PopIIb stars. We calculate the rates of interstellar gas production by stellar winds and the rates of gas accretion to estimate the changes in the globular cluster stars abundances. We compare those results to our observations.
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Jehin, Emmanuel  ;  Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Astrophysique et traitement de l'image
Magain, Pierre  ;  Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Astrophysique et traitement de l'image
Neuforge, Corinne
Noels-Grötsch, Arlette ;  Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Département d'astrophys., géophysique et océanographie (AGO)
Parmentier, Geneviève ;  Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Astrophysique et traitement de l'image
Thoul, Anne  ;  Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Evol. et stabilité des étoiles et des amas d'étoiles (ESEA)
Language :
English
Title :
The impact of AGB stars on the chemical evolution of globular clusters
Publication date :
1998
Event name :
Asymptotic Giant Branch Stars
Event organizer :
International Astronomical Union
Event place :
Montpellier, France
Event date :
du 28 août 1998 au 1 septembre 1998
Audience :
International
Main work title :
Asymptotic Giant Branch Stars
Collection name :
IAU Symposium 191
Pages :
603P
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