Cayrel's Star

BPS CS31082-0001, named Cayrel's Star /keɪˈrɛlz/,[3] is an old Population II star located in a distance of 2.1 kpc[1] in the galactic halo. It belongs to the class of ultra-metal-poor stars (metallicity [Fe/H] = -2.9), specifically the very rare subclass of neutron-capture 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 and analyzed by Roger Cayrel and collaborators. They used the Very Large Telescope (VLT) at the European Southern Observatory in Paranal, Chile for high-resolution optical spectroscopy to determine elemental abundances. The thorium-232 to uranium-238 ratio was used to determine the age. It is estimated to be about 12.5 billion years old, making it one of the oldest known.

BPS CS31082-0001
Observation data
Epoch J2000      Equinox J2000
Constellation Cetus
Right ascension 01h 29m 31.1311s[1]
Declination −16° 00′ 45.496″[1]
Apparent magnitude (V) 11.642[2]
Astrometry
Proper motion (μ) RA: 11.745[1] mas/yr
Dec.: −42.709[1] mas/yr
Parallax (π)0.4806 ± 0.0462 mas[1]
Distance6,800 ± 700 ly
(2,100 ± 200 pc)
Other designations
BD−16° 251, CS31082-001, Cayrel's Star
Database references
SIMBADdata

Compared to other ultra-metal-poor, r-process enriched stars (as CS22892-052, BD +17° 3248, HE 1523-0901) CS31082-001 has higher abundances of the actinides (Th, U), but a surprisingly low Pb abundance.

See also

References
  1. 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.
  2. Munari, U.; Henden, A.; Frigo, A.; Zwitter, T.; Bienaymé, O.; Bland-Hawthorn, J.; Boeche, C.; Freeman, K. C.; Gibson, B. K.; Gilmore, G.; Grebel, E. K.; Helmi, A.; Kordopatis, G.; Levine, S. E.; Navarro, J. F.; Parker, Q. A.; Reid, W.; Seabroke, G. M.; Siebert, A.; Siviero, A.; Smith, T. C.; Steinmetz, M.; Templeton, M.; Terrell, D.; Welch, D. L.; Williams, M.; Wyse, R. F. G. (2014). "APASS Landolt-Sloan BVgri Photometry of RAVE Stars. I. Data, Effective Temperatures, and Reddenings". The Astronomical Journal. 148 (5): 81. arXiv:1408.5476. Bibcode:2014AJ....148...81M. doi:10.1088/0004-6256/148/5/81. hdl:1885/19979. S2CID 56127278.
  3. Space Math @ NASA

Sources
  • Beers, T. C., G. W. Preston and S. A. Shectman, A search for stars of very low metal abundance. I., Astron. J., 90, 2089–2102 (1985)
  • Beers, T. C., G. W. Preston and S. A. Shectman, A search for stars of very low metal abundance. II., Astron. J., 103, 1987–2034 (1992)
  • Cayrel, R., et al. Measurement of stellar age from uranium decay, Nature, Volume 409, Issue 6821, pp. 691–692 (2001)
  • Schatz, H., al. Thorium and Uranium Chronometres applied to CS 31082-001, Astrophysical Journal, 579 (2002) 628–638
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