2006ApJ...645..613I -
Astrophys. J., 645, 613-633 (2006/July-1)
Near-ultraviolet observations of HD 221170: new insights into the nature of r-process-rich stars.
IVANS I.I., SIMMERER J., SNEDEN C., LAWLER J.E., COWAN J.J., GALLINO R. and BISTERZO S.
Abstract (from CDS):
Employing high-resolution spectra obtained with the near-UV-sensitive detector on the Keck I HIRES, supplemented by data obtained with the McDonald Observatory 2d-coudé, we have performed a comprehensive chemical composition analysis of the bright r-process-rich metal-poor red giant star HD 221170. Analysis of 57 individual neutral and ionized species yielded abundances for a total of 46 elements and significant upper limits for an additional five. Model stellar atmosphere parameters were derived with the aid of ∼200 Fe peak transitions. From more than 350 transitions of 35 neutron-capture (Z>30) species, abundances for 30 neutron-capture elements and upper limits for three others were derived. Utilizing 36 transitions of La, 16 of Eu, and seven of Th, we derive ratios of logε(Th/La)=-0.73 (σ=0.06) and logε(Th/Eu)=-0.60 (σ=0.05), values in excellent agreement with those previously derived for other r-process-rich metal-poor stars such as CS 22892-052, BD +17 3248, and HD 115444. Based on the Th/Eu chronometer, the inferred age is 11.7±2.8 Gyr. The abundance distribution of the heavier neutron-capture elements (Z≥56) is fitted well by the predicted scaled solar system r-process abundances, as also seen in other r-process-rich stars. Unlike other r-process-rich stars, however, we find that the abundances of the lighter neutron-capture elements (37<Z<56) in HD 221170 are also in agreement with the abundances predicted for the scaled solar r-process pattern.
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Journal keyword(s):
Galaxy: Abundances - Galaxy: Evolution - Nuclear Reactions, Nucleosynthesis, Abundances - Stars: Abundances - stars: individual (HD 221170) - Stars: Population II
VizieR on-line data:
<Available at CDS (J/ApJ/645/613): table1.dat table2.dat table4.dat table6.dat>
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