Algorithms for neutron density and s-process nucleosynthesis in a low-mass asymptotic giant branch star

1990 ◽  
Vol 349 ◽  
pp. 208 ◽  
Author(s):  
David Hollowell ◽  
Icko, Jr. Iben
Keyword(s):  
Asymptotic Giant Branch ◽  
Neutron Density ◽  
Asymptotic Giant Branch Star ◽  
Low Mass ◽  
Branch Star

Rubidium in Barium Stars

2020 ◽  
Author(s):  
M P Roriz ◽  
M Lugaro ◽  
C B Pereira ◽  
N A Drake ◽  
S Junqueira ◽  
...  
Keyword(s):  
Neutron Source ◽  
Slow Neutron ◽  
Asymptotic Giant Branch ◽  
Neutron Density ◽  
Data Sets ◽  
Agb Stars ◽  
Branching Points ◽  
Theoretical Predictions ◽  
Low Mass ◽  
Chemically Peculiar Stars

Abstract Barium (Ba) stars are chemically peculiar stars that display in their atmospheres the signature of the slow neutron-capture (the s-process) mechanism that occurs in asymptotic giant branch (AGB) stars, a main contributor to the cosmic abundances. The observed chemical peculiarity in these objects is not due to self-enrichment, but to mass transfer between the components of a binary system. The atmospheres of Ba stars are therefore excellent astrophysical laboratories providing strong constraints for the nucleosynthesis of the s-process in AGB stars. In particular, rubidium (Rb) is a key element for the s-process diagnostic because it is sensitive to the neutron density and therefore its abundance can reveal the main neutron source for the s-process in AGB stars. We present Rb abundances for a large sample of 180 Ba stars from high resolution spectra (R = 48000), and we compare the observed [Rb/Zr] ratios with theoretical predictions from AGB s-process nucleosynthesis models. The target Ba stars in this study display [Rb/Zr] <0, showing that Rb was not efficiently produced by the activation of branching points. Model predictions from the Monash and FRUITY data sets of low-mass (≲ 4 M⊙) AGB stars are able to cover the Rb abundances observed in the target Ba stars. These observations indicate that the 13C(α,n)16O reaction is the main neutron source of the s-process in the low-mass AGB companions of the observed Ba stars. We have not found in the present study candidate companion for IR/OH massive AGB stars.

scholarly journals On the asymptotic giant branch star origin of peculiar spinel grain OC2

2006 ◽  
Vol 461 (2) ◽  
pp. 657-664 ◽  
Author(s):  
M. Lugaro ◽  
A. I. Karakas ◽  
L. R. Nittler ◽  
C. M. O'D. Alexander ◽  
P. Hoppe ◽  
...  
Keyword(s):  
Asymptotic Giant Branch ◽  
Asymptotic Giant Branch Star ◽  
Branch Star

scholarly journals THE ASTROSPHERE OF THE ASYMPTOTIC GIANT BRANCH STAR IRC+10216

2010 ◽  
Vol 711 (2) ◽  
pp. L53-L56 ◽  
Author(s):  
Raghvendra Sahai ◽  
Christopher K. Chronopoulos
Keyword(s):  
Asymptotic Giant Branch ◽  
Asymptotic Giant Branch Star ◽  
Branch Star
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