The Chemical Composition and Age of the Metal-Poor Halo Star BD +17^\circ 3248

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dc.creatorCowan, John J.
dc.creatorSneden, Christopher
dc.creatorBurles, Scott
dc.creatorIvans, Inese I.
dc.creatorBeers, Timothy C.
dc.creatorTruran, James W.
dc.creatorLawler, James E.
dc.creatorPrimas, Francesca
dc.creatorFuller, George M.
dc.creatorPfeiffer, Bernd
dc.creatorKratz, Karl-Ludwig
dc.date2002-02-22
dc.date.accessioned2026-07-07T10:31:12Z
dc.date.available2026-07-07T10:31:12Z
dc.descriptionWe have combined new high-resolution spectra obtained with the Hubble Space Telescope (HST) and ground-based facilities to make a comprehensive new abundance analysis of the metal-poor, halo star BD +17^\circ 3248. We have detected the third r-process peak elements osmium, platinum, and (for the first time in a metal-poor star) gold, elements whose abundances can only be reliably determined using HST. Our observations illustrate a pattern seen in other similar halo stars with the abundances of the heavier neutron-capture elements, including the third r-process peak elements, consistent with a scaled solar system r-process distribution. The abundances of the lighter neutron-capture elements, including germanium and silver, fall below that same scaled solar r-process curve, a result similar to that seen in the ultra-metal-poor star CS 22892--052. A single site with two regimes or sets of conditions, or perhaps two different sites for the lighter and heavier neutron-capture elements, might explain the abundance pattern seen in this star. In addition we have derived a reliable abundance for the radioactive element thorium. We tentatively identify U II at 3859 A in the spectrum of BD +17^\circ 3248, which makes this the second detection of uranium in a very metal-poor halo star. Our combined observations cover the widest range in proton number (from germanium to uranium) thus far of neutron-capture elements in metal-poor Galactic halo stars. Employing the thorium and uranium abundances in comparison with each other and with several stable elements, we determine an average cosmochronological age for BD +17^\circ 3248 of 13.8 +/- 4 Gyr, consistent with that found for other similar metal-poor halo stars.
dc.description58 pages, 4 tables, 11 figures; To appear in ApJ Typo corrected
dc.identifierhttps://arxiv.org/abs/astro-ph/0202429
dc.identifierhttp://arxiv.org/abs/astro-ph/0202429
dc.identifierAstrophys.J.572:861-879,2002
dc.identifierdoi:10.1086/340347
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/178330
dc.subjectAstrophysics
dc.titleThe Chemical Composition and Age of the Metal-Poor Halo Star BD +17^\circ 3248
dc.typetext

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