SIMBAD references

2018ApJ...854L..20S - Astrophys. J., 854, L20-L20 (2018/February-3)

The r-process pattern of a bright, highly r-process-enhanced metal-poor halo star at [Fe/H] ∼ -2.

SAKARI C.M., PLACCO V.M., HANSEN T., HOLMBECK E.M., BEERS T.C., FREBEL A., ROEDERER I.U., VENN K.A., WALLERSTEIN G., DAVIS C.E., FARRELL E.M. and YONG D.

Abstract (from CDS):

A high-resolution spectroscopic analysis is presented for a new highly r-process-enhanced ([Eu/Fe] = 1.27, [Ba/Eu] = -0.65), very metal-poor ([Fe/H] = -2.09), retrograde halo star, RAVE J153830.9-180424, discovered as part of the R-Process Alliance survey. At V = 10.86, this is the brightest and most metal-rich r-II star known in the Milky Way halo. Its brightness enables high-S/N detections of a wide variety of chemical species that are mostly created by the r-process, including some infrequently detected lines from elements like Ru, Pd, Ag, Tm, Yb, Lu, Hf, and Th, with upper limits on Pb and U. This is the most complete r-process census in a very metal-poor r-II star. J1538-1804 shows no signs of s-process contamination, based on its low [Ba/Eu] and [Pb/Fe]. As with many other r-process-enhanced stars, J1538-1804's r-process pattern matches that of the Sun for elements between the first, second, and third peaks, and does not exhibit an actinide boost. Cosmo-chronometric age-dating reveals the r-process material to be quite old. This robust main r-process pattern is a necessary constraint for r-process formation scenarios (of particular interest in light of the recent neutron star merger, GW170817), and has important consequences for the origins of r-II stars. Additional r-I and r-II stars will be reported by the R-Process Alliance in the near future.

Abstract Copyright: © 2018. The American Astronomical Society. All rights reserved.

Journal keyword(s): Galaxy: formation - stars: abundances - stars: atmospheres - stars: fundamental parameters

Simbad objects: 6

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