2017A&A...607A..91H -
Astronomy and Astrophysics, volume 607A91-91 (2017/11-1)
The Hamburg/ESO R-process Enhanced Star survey (HERES). XI. The highly r-process-enhanced star CS 29497-004.
HILL V., CHRISTLIEB N., BEERS T.C., BARKLEM P.S., KRATZ K.-L., NORDSTROM B., PFEIFFER B. and FAROUQI K.
Abstract (from CDS):
We report an abundance analysis for the highly r-process-enhanced (r-II) star CS 29497-004, a very metal-poor giant with solar system T
eff=5013K and [Fe/H]=-2.85, whose nature was initially discovered in the course of the HERES project. Our analysis is based on high signal-to-noise ratio, high-resolution (R∼75000) VLT/UVES spectra and MARCS model atmospheres under the assumption of local thermodynamic equilibrium, and obtains abundance measurements for a total of 46 elements, 31 of which are neutron-capture elements. As is the case for the other ∼25 r-II stars currently known, the heavy-element abundance pattern of CS 29497-004 well-matches a scaled solar system second peak r-process-element abundance pattern. We confirm our previous detection of Th, and demonstrate that this star does not exhibit an "actinide boost". Uranium is also detected (log ε(U)=-2.20±0.30), albeit with a large measurement error that hampers its use as a precision cosmo-chronometer. Combining the various elemental chronometer pairs that are available for this star, we derive a mean age of 12.2±3.7Gyr using the theoretical production ratios from published waiting-point approximation models. We further explore the high-entropy wind model (Farouqi et al.,
2010ApJ...712.1359F) production ratios arising from different neutron richness of the ejecta (Y
e), and derive an age of 13.7±4.4Gyr for a best-fitting Y
e=0.447. The U/Th nuclei-chronometer is confirmed to be the most resilient to theoretical production ratios and yields an age of 16.5±6.6Gyr. Lead (Pb) is also tentatively detected in CS 29497-004, at a level compatible with a scaled solar r-process, or with the theoretical expectations for a pure r-process in this star.
Abstract Copyright:
© ESO, 2017
Journal keyword(s):
stars: abundances - stars: individual: CS 29497-004 - stars: Population II - stars: chemically peculiar - Galaxy: halo - Galaxy: halo
VizieR on-line data:
<Available at CDS (J/A+A/607/A91): tableb1.dat>
Simbad objects:
8
Full paper
View the references in ADS
To bookmark this query, right click on this link: simbad:2017A&A...607A..91H and select 'bookmark this link' or equivalent in the popup menu