Star in the constellation Hercules
BD+17°3248 is an old Population II star located at a distance of roughly 968 light-years (297 parsecs ) in the Galactic Halo . It belongs to the class of ultra-metal-poor stars,[ 5] r-process ) enhanced stars.
Since about 2000, the star has been studied with 3 telescopes: the Hubble Space Telescope , the Keck I telescope and the Harlan J. Smith Telescope at the McDonald Observatory of the University of Texas . Elemental
abundances in the range from germanium (Z=32) up to uranium (Z=92) have been determined. The Hubble Space Telescope was used to observe the ultraviolet part of the stellar spectra. This allowed the measurement of platinum , osmium and, for the first time outside of the Solar System, gold . From barium (Z=56) onward, all elements show a pattern of r-process contribution to the abundances of the elements in the Solar system .[ 5]
The University of Mainz and University of Basel groups of Karl-Ludwig Kratz and Friedrich-Karl Thielemann performed a comparison between the observed abundances for the stable element europium (Z=63) and the radioactive elements thorium (Z=90) and uranium (Z=92) to the calculated abundances of an r-process in a Type II supernova explosion. This allowed the age of this star to be estimated as about 13.8 billion years with an uncertainty of 4 billion years. A similar age was derived for another ultra-metal-poor star (CS31082-001 ) from thorium to uranium ratios. These stars were born several hundred million years after the Big Bang .[ 5]
References
^ a b c d Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties" . Astronomy and Astrophysics . 674 : A1. arXiv :2208.00211 Bibcode :2023A&A...674A...1G . doi :10.1051/0004-6361/202243940 S2CID 244398875 . Gaia DR3 record for this source at VizieR .^ a b c Carney, B. W. (May 1983), "A photometric search for halo binaries. I - New observational data", Astronomical Journal , 88 : 610– 641, Bibcode :1983AJ.....88..610C , doi :10.1086/113350 ^ a b "BD+17 3248" . SIMBAD Centre de données astronomiques de Strasbourg . Retrieved 2012-03-10 .^ Bonifacio; et al. (July 2009), "First stars XII. Abundances in extremely metal-poor turnoff stars, and comparison with the giants", Astronomy and Astrophysics , 501 (2): 519– 530, arXiv :0903.4174 Bibcode :2009A&A...501..519B , doi :10.1051/0004-6361/200810610 , S2CID 119164253 ^ a b c d e f g Cowan, John J.; et al. (June 2002), "The Chemical Composition and Age of the Metal-poor Halo Star BD +17°3248", The Astrophysical Journal , 572 (2): 861– 879, arXiv :astro-ph/0202429 Bibcode :2002ApJ...572..861C , doi :10.1086/340347 , S2CID 119503888 ^ a b Brown, A. G. A. ; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties" . Astronomy & Astrophysics 616 . A1. arXiv :1804.09365 Bibcode :2018A&A...616A...1G doi :10.1051/0004-6361/201833051 Gaia DR2 record for this source at VizieR .^ a b Burris, Debra L.; et al. (November 2000), "Neutron-Capture Elements in the Early Galaxy: Insights from a Large Sample of Metal-poor Giants", The Astrophysical Journal , 544 (1): 302– 319, arXiv :astro-ph/0005188 Bibcode :2000ApJ...544..302B , doi :10.1086/317172 , S2CID 33015452
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