Neutron production and neutron-capture nucleosynthesis in a low-mass, low-metallicity asymptotic giant branch star

1989 ◽  
Vol 340 ◽  
pp. 966 ◽  
Author(s):  
David Hollowell ◽  
Icko, Jr. Iben
Keyword(s):  
Neutron Capture ◽  
Neutron Production ◽  
Asymptotic Giant Branch ◽  
Asymptotic Giant Branch Star ◽  
Low Metallicity ◽  
Low Mass ◽  
Branch Star

scholarly journals THREE-DIMENSIONAL HYDRODYNAMICAL SIMULATIONS OF A PROTON INGESTION EPISODE IN A LOW-METALLICITY ASYMPTOTIC GIANT BRANCH STAR

2011 ◽  
Vol 742 (2) ◽  
pp. 121 ◽  
Author(s):  
Richard J. Stancliffe ◽  
David S. P. Dearborn ◽  
John C. Lattanzio ◽  
Stuart A. Heap ◽  
Simon W. Campbell
Keyword(s):  
Three Dimensional ◽  
Asymptotic Giant Branch ◽  
Asymptotic Giant Branch Star ◽  
Low Metallicity ◽  
Hydrodynamical Simulations ◽  
Branch Star

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 Unusual neutron-capture nucleosynthesis in a carbon-rich Galactic bulge star

2019 ◽  
Vol 622 ◽  
pp. A159 ◽  
Author(s):  
Andreas Koch ◽  
Moritz Reichert ◽  
Camilla Juul Hansen ◽  
Melanie Hampel ◽  
Richard J. Stancliffe ◽  
...  
Keyword(s):  
Neutron Capture ◽  
Galactic Halo ◽  
Asymptotic Giant Branch ◽  
Galactic Bulge ◽  
Element Abundances ◽  
Intermediate Neutron ◽  
Low Mass ◽  
Process Component ◽  
Process Elements ◽  
The Impact

Metal-poor stars in the Galactic halo often show strong enhancements in carbon and/or neutron-capture elements. However, the Galactic bulge is notable for its paucity of these carbon-enhanced metal-poor (CEMP) and/or CH-stars, with only two such objects known to date. This begs the question whether the processes that produced their abundance distribution were governed by a comparable nucleosynthesis in similar stellar sites as for their more numerous counterparts in the halo. Recently, two contenders of these classes of stars were discovered in the bulge, at [Fe/H] = −1.5 and −2.5 dex, both of which show enhancements in [C/Fe] of 0.4 and 1.4 dex (respectively), [Ba/Fe] in excess of 1.3 dex, and also elevated nitrogen. The more metal-poor of the stars can be well matched by standard s-process nucleosynthesis in low-mass asymptotic giant branch (AGB) polluters. The other star shows an abnormally high [Rb/Fe] ratio. Here, we further investigate the origin of the abundance peculiarities in the Rb-rich star by new, detailed measurements of heavy element abundances and by comparing the chemical element ratios of 36 species to several models of neutron-capture nucleosynthesis. The i-process with intermediate neutron densities between those of the slow (s-) and rapid (r)-neutron-capture processes has been previously found to provide good matches of CEMP stars with enhancements in both r- and s-process elements (class CEMP-r/s), rather than invoking a superposition of yields from the respective individual processes. However, the peculiar bulge star is incompatible with a pure i-process from a single ingestion event. Instead, it can, statistically, be better reproduced by more convoluted models accounting for two proton ingestion events, or by an i-process component in combination with s-process nucleosynthesis in low-to-intermediate mass (2–3 M⊙) AGB stars, indicating multiple polluters. Finally, we discuss the impact of mixing during stellar evolution on the observed abundance peculiarities.

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