- BD+173248 (star)
Starbox begin
name=BD +17° 3248 Starbox observe
epoch=J2000
constell=Hercules
ra=17h 28m 14s
dec=+17° 30' 36"
appmag_v=9.4 BD +17° 3248 is an old Population IIstar located in a distance of 272 pc in theGalactic Halo . It belongs to the class of ultra-metal-poor stars (Metallicity Fe/H =–3.1) , especially the very rare subclass of neutron-capture (r-process ) enhanced stars.Since about 2000, this star had been analyzed with 3 telescopes: a) the
Hubble Space Telescope , b) the Keck I telescope and c) theHarlan J. Smith Telescope at theMcDonald Observatory of theUniversity of Texas . Elemental abundances in the range fromGermanium (Z=32) up toUranium (Z=92) could be determined. With the Hubble Space Telescope also theultraviolet part of the stellar spectra could be observed. This allowed to measurePlatinum ,Osmium and for the first time outside of the Solar SystemGold . FromBarium (Z=56) on, all elements show the pattern of the r-process contribution to the
abundances of the elements in the Solar system. Comparing the observed abundances for a stable element asEuropium (Z=63) and the radioactive elementsThorium (Z=90) andUranium (Z=92) to calculated abundances of an r-process in a type II supernova explosion (as from the universities at Mainz and Basel groups ofKarl-Ludwig Kratz andFriedrich-Karl Thielemann ) allowed to determine the age of this star to about 13.8 billion years (with an uncertainty of 4 billion years). A similar age had been derived for another ultra-metal-poor star(CS31082-001 from Thorium toUranium ratios. These stars were already born several hundred million years after theBig Bang .References
* Beers T.C., Preston G.W., Shectman S.A., "A search for stars of very low metal abundance. I.", Astron. J., 90, 2089-2102 (1985)
* Beers T.C., Preston G.W., Shectman S.A., "A search for stars of very low metal abundance. II.", Astron. J., 103, 1987-2034 (1992)
* Kratz, Karl-Ludwig; Bitouzet, Jean-Philippe; Thielemann, Friedrich-Karl; Moeller, Peter; Pfeiffer, Bernd, "Isotopic r-process abundances and nuclear structure far from stability - Implications for the r-process mechanism", Astrophysical Journal, vol. 403, no. 1, p. 216-238 (1993)
* Sneden, Christopher; McWilliam, Andrew; Preston, George W.; Cowan, John J.; Burris, Debra L.; Armosky, Bradley J., "The Ultra--Metal-poor, Neutron-Capture--rich Giant Star CS 22892-052", Astrophysical Journal v.467, p.819 (1996)
* J.J. Cowan, C. Sneden, S. Burles, I.I. Ivans, T.C. Beers, J.W. Truran, J.E. Lawler, F. Primas, G.M. Fuller, B. Pfeiffer, and K.-L. Kratz: "The Chemical Composition and Age of the Metal-Poor Halo Star BD +17°3248", Ap.J. 572 (2002) 861 - 879External links
* [http://simbad.u-strasbg.fr/sim-id.pl?protocol=html&Ident=bps+cs22892-0052 SIMBAD-Entry] (
SIMBAD )
* [http://dkcmzc.chemie.uni-mainz.de/~pfeiffer/ages.html R-Process Cosmo-Chronometers]
* [http://xxx.arxiv.org/abs/astro-ph/0202429 "The Chemical Composition and Age of the Metal-Poor Halo Star BD +17°3248"]
* [http://www.eurekalert.org/pub_releases/2002-01/msu-adg011002.php Discovery of Gold]
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