Astronomy:Sneden's Star

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Short description: Star in the constellation Aquarius
Sneden's Star
Observation data
Equinox J2000.0]] (ICRS)
Constellation Aquarius
Right ascension  22h 17m 01.65585s[1]
Declination −16° 39′ 27.0519″[1]
Apparent magnitude (V) 13.21[2]
Characteristics
Spectral type KIIvw[3][failed verification]
B−V color index 0.78[3]
Astrometry
Radial velocity (Rv)+13.0[2] km/s
Proper motion (μ) RA: 12.321[1] mas/yr
Dec.: −6.493[1] mas/yr
Parallax (π)0.1868 ± 0.0440[1] mas
Distanceapprox. 17,000 ly
(approx. 5,000 pc)
Absolute magnitude (MV)−0.23[4]
Details
Mass1.13[5] M☉
Radius13.8[6] R☉
Surface gravity (log g)1.15[2] cgs
Temperature4,690[2] K
Metallicity [Fe/H]−3.19[3] dex
Age13 Gyr
Other designations
BPS CS 22892-0052, HE 2214-1654[7]
Database references
SIMBADdata

BPS CS22892-0052 (Sneden's Star) is an old population II star located at a distance of 4.7 kiloparsecs (15,000 light-years) in the Milky Way's galactic halo. It belongs to a class of ultra-metal-poor stars (metallicity [Fe/H]=-3.1), specifically the very rare subclass of neutron-capture (r-process) enhanced stars. It was discovered by Tim C. Beers and collaborators with the Curtis Schmidt telescope at the Cerro Tololo Inter-American Observatory in Chile . Extended high-resolution spectroscopic observations since around 1995 (with Chris Sneden from the University of Texas at Austin as the leading observer) allowed observers to determine the abundances of 53 chemical elements in this star, as of December 2005 only second in number to the Sun.

From barium (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 such as europium (Z=63) and the radioactive element thorium (Z=90) to calculated abundances of an r-process in a type II supernova explosion (as from the universities at Mainz and Basel groups of Karl-Ludwig Kratz and Friedrich-Karl Thielemann) have allowed observers to determine the age of this star to be about 13 billion years. Similar ages have been derived for other ultra-metal-poor stars (CS31082-001, BD+17°3248 and HE 1523-0901) from thorium-to-uranium ratios.

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 Brown, A. G. A. (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics 616: A1. doi:10.1051/0004-6361/201833051. Bibcode: 2018A&A...616A...1G.  Gaia DR2 record for this source at VizieR.
  2. ↑ 2.0 2.1 2.2 2.3 Roederer, Ian U. et al. (June 2014). "A Search for Stars of Very Low Metal Abundance. VI. Detailed Abundances of 313 Metal-poor Stars". The Astronomical Journal 147 (6): 57. doi:10.1088/0004-6256/147/6/136. 136. Bibcode: 2014AJ....147..136R. 
  3. ↑ 3.0 3.1 3.2 Norris, John E. et al. (October 1997). "Extremely Metal-poor Stars. IV. The Carbon-rich Objects". The Astrophysical Journal 488 (1): 350–363. doi:10.1086/304695. Bibcode: 1997ApJ...488..350N. 
  4. ↑ Beers, Timothy C.; Preston, George W.; Shectman, Stephen A. (1992). "A Search for Stars of Very Low Metal Abundance. II". The Astronomical Journal 103: 1987. doi:10.1086/116207. Bibcode: 1992AJ....103.1987B. 
  5. ↑ Anders, F.; Khalatyan, A.; Chiappini, C.; Queiroz, A. B.; Santiago, B. X.; Jordi, C.; Girardi, L.; Brown, A. G. A. et al. (2019-08-01). "Photo-astrometric distances, extinctions, and astrophysical parameters for Gaia DR2 stars brighter than G = 18". Astronomy and Astrophysics 628: A94. doi:10.1051/0004-6361/201935765. ISSN 0004-6361. Bibcode: 2019A&A...628A..94A. 
  6. ↑ Stassun, Keivan G.; Oelkers, Ryan J.; Paegert, Martin; Torres, Guillermo; Pepper, Joshua; De Lee, Nathan; Collins, Kevin; Latham, David W. et al. (2019-10-01). "The Revised TESS Input Catalog and Candidate Target List". The Astronomical Journal 158 (4): 138. doi:10.3847/1538-3881/ab3467. ISSN 0004-6256. Bibcode: 2019AJ....158..138S. 
  7. ↑ "BPS CS 22892-0052". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=BPS+CS+22892-0052. 

Sources

  • 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)
  • Cowan, John J.; Pfeiffer, B.; Kratz, K.-L.; Thielemann, F.-K.; Sneden, Christopher; Burles, Scott; Tytler, David; Beers, Timothy C., R-Process Abundances and Chronometers in Metal-poor Stars The Astrophysical Journal, Volume 521, Issue 1, pp. 194–205 (1999)

External links



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