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The Mystery of CEMPs+r Stars and the Dual Core-Flash Neutron Superburst

Published online by Cambridge University Press:  05 March 2013

M. Lugaro ,
S. W. Campbell  and
S. E. de Mink
M. Lugaro*
Affiliation:
Centre for Stellar and Planetary Astrophysics, School of Mathematical Sciences, Monash University, Clayton, VIC 3800 Sterrekundig Instituut, University of Utrecht, Postbus 80 000, 3508 TA Utrecht, The Netherlands
S. W. Campbell
Affiliation:
Centre for Stellar and Planetary Astrophysics, School of Mathematical Sciences, Monash University, Clayton, VIC 3800 Departament de Física i Enginyeria Nuclear, EUETIB, Universita Politècnica de Catalunya, E-08036, Barcelona, Spain
S. E. de Mink
Affiliation:
Sterrekundig Instituut, University of Utrecht, Postbus 80 000, 3508 TA Utrecht, The Netherlands
*
DCorresponding author. Email: [email protected]
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Abstract

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Carbon-enhanced metal-poor (CEMPs+r) stars show large enhancements of elements produced both by the slow and the rapid neutron capture processes (the s and r process, respectively) and represent a relatively large fraction, 30% to 50%, of the CEMP population. Many scenarios have been proposed to explain this peculiar chemical composition and most of them involve a binary companion producing the s-process elements during its Asymptotic Giant Branch (AGB) phase. The problem is that none of the proposed explanations appears to be able to account for all observational constraints, hence, alternatives are needed to be put forward and investigated. In this spirit, we propose a new scenario for the formation of CEMPs+r stars based on S. W. Campbell's finding that during the ‘dual core flash’ in low-mass stars of extremely low metallicity, when protons are ingested in the He-flash convective zone, a ‘neutron superburst’ is produced. Further calculations are needed to verify if this neutron superburst could make the r-process component observed in CEMPs+r, as well as their Fe abundances. The s-process component would then be produced during the following AGB phase.

Keywords

nuclear reactions, nucleosynthesis, abundancesstars: AGB and post-AGBbinaries: generalstars: chemically peculiarstars: Population II
Type
CEMP Stars
Information
Publications of the Astronomical Society of Australia , Volume 26 , Issue 3 , 2009 , pp. 322 - 326
Copyright
Copyright © Astronomical Society of Australia 2009

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