| Full text | |
| Author(s): Show less - |
Ezzeddine, Rana
;
Rasmussen, Kaitlin
;
Frebel, Anna
;
Chiti, Anirudh
;
Hinojisa, Karina
;
Placco, Vinicius M.
;
Ji, Alexander P.
;
Beers, Timothy C.
;
Hansen, Terese T.
;
Roederer, Ian U.
;
Sakari, Charli M.
;
Melendez, Jorge
Total Authors: 12
|
| Document type: | Journal article |
| Source: | ASTROPHYSICAL JOURNAL; v. 898, n. 2, p. 29-pg., 2020-08-01. |
| Abstract | |
Extensive progress has recently been made in our understanding of heavy-element production via ther-process in the universe, specifically with the first observed neutron star binary merger (NSBM) event associated with the gravitational-wave signal detected by LIGO, GW170817. The chemical abundance patterns of metal-poorr-process-enhanced stars provide key evidence for the dominant site(s) of ther-process and whether NSBMs are sufficiently frequent or prolificr-process sources to be responsible for the majority ofr-process material in the universe. We present atmospheric stellar parameters (using a nonlocal thermodynamic equilibrium analysis) and abundances from a detailed analysis of 141 metal-poor stars carried out as part of theR-Process Alliance (RPA) effort. We obtained high-resolution "snapshot" spectroscopy of the stars using the MIKE spectrograph on the 6.5 m Magellan Clay telescope at Las Campanas Observatory in Chile. We find 10 new highly enhancedr-II (with [Eu/Fe] > +1.0), 62 new moderately enhancedr-I (+0.3 < [Eu/Fe] <= +1.0), and 17 new limited-r([Eu/Fe] < +0.3) stars. Among those, we find 17 new carbon-enhanced metal-poor (CEMP) stars, of which five are CEMP-no. We also identify one news-process-enhanced ([Ba/Eu] > +0.5) and five newr/s(0.0 < [Ba/Eu] < +0.5) stars. In the process, we discover a new ultra-metal-poor (UMP) star at [Fe/H] = -4.02. One of ther-II stars shows a deficit in alpha and Fe-peak elements, typical of dwarf galaxy stars. Our search forr-process-enhanced stars by RPA efforts has already roughly doubled the knownr-process sample. (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 |