| Full text | |
| Author(s): Show less - |
Cain, Madelyn
[1, 2]
;
Frebel, Anna
[1, 2, 3]
;
Gull, Maude
[1, 2]
;
Ji, Alexander P.
[4]
;
Placco, Vinicius M.
[5, 3]
;
Beers, Timothy C.
[5, 3]
;
Melendez, Jorge
[6]
;
Ezzeddine, Rana
[1, 2, 3]
;
Casey, Andrew R.
[7]
;
Hansen, Terese T.
[4]
;
Roederer, Ian U.
[8, 3]
;
Sakari, Charli
[9, 3]
Total Authors: 12
|
| Affiliation: | [1] MIT, Dept Phys, Cambridge, MA 02139 - USA
[2] MIT, Kavli Inst Astrophys & Space Res, 77 Massachusetts Ave, Cambridge, MA 02139 - USA
[3] Joint Inst Nucl Astrophys, Ctr Evolut Elements, Notre Dame, IN 46556 - USA
[4] Carnegie Inst Washington Observ, 813 Santa Barbara St, Pasadena, CA 91101 - USA
[5] Univ Notre Dame, Dept Phys, Notre Dame, IN 46556 - USA
[6] Univ Sao Paulo, Inst Astron Geofis & Ciencias Atmosfer, BR-05508900 Sao Paulo, SP - Brazil
[7] Monash Univ, Sch Phys & Astron, Monash Ctr Astrophys, Melbourne, Vic 3800 - Australia
[8] Univ Michigan, Dept Astron, Ann Arbor, MI 48109 - USA
[9] Univ Washington, Dept Astron, Seattle, WA 98195 - USA
Total Affiliations: 9
|
| Document type: | Journal article |
| Source: | ASTROPHYSICAL JOURNAL; v. 864, n. 1 SEP 1 2018. |
| Web of Science Citations: | 2 |
| Abstract | |
We present detailed chemical abundances of three new bright (V similar to 11), extremely metal-poor ({[}Fe/H]similar to -3.0), r-process- enhanced halo red giants based on high-resolution, high-S/N Magellan/MIKE spectra. We measured abundances for 20-25 neutron- capture elements in each of our stars. J1432-4125 is among the most r-process-rich r-II stars, with {[}Eu/Fe] = +1.44 +/- 0.11. J2005-3057 is an r-I star with {[}Eu/Fe] = +0.94 +/- 0.07. J0858-0809 has {[}Eu/Fe] = +0.23 +/- 0.05 and exhibits a carbon abundance corrected for an evolutionary status of {[}C/Fe] corr = +0.76, thus adding to the small number of known carbon-enhanced r-process stars. All three stars show remarkable agreement with the scaled solar r-rocess pattern for elements above Ba, consistent with enrichment of the birth gas cloud by a neutron star merger. The abundances for Sr, Y, and Zr, however, deviate from the scaled solar pattern. This indicates that more than one distinct r-process site might be responsible for the observed neutron-capture element abundance pattern. Thorium was detected in J1432-4125 and J2005-3057. Age estimates for J1432-4125 and J2005-3057 were adopted from one of two sets of initial production ratios each by assuming the stars are old. This yielded individual ages of 12 +/- 6 Gyr and 10 +/- 6 Gyr, respectively. (AU) | |
| FAPESP's process: | 14/18100-4 - Stellar populations in the Milky Way: bulge, halo, disk and star forming regions; instrumentation for high resolution spectroscopy |
| Grantee: | Beatriz Leonor Silveira Barbuy |
| Support Opportunities: | Research Projects - Thematic Grants |
| FAPESP's process: | 12/24392-2 - High precision spectroscopy: impact in the study of planets, stars, the galaxy and cosmology |
| Grantee: | Jorge Luis Melendez Moreno |
| Support Opportunities: | Research Projects - Thematic Grants |