Cayrel's Star
From Wikipedia, the free encyclopedia
| Observation data Epoch J2000 |
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|---|---|
| Constellation | Cetus |
| Right ascension | 01h 29m 30.31s |
| Declination | -16° 08' 5.51" |
| Apparent magnitude (V) | 11.7 |
| Other designations | |
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BD -16°251, CS31082-001
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BPS CS31082-0001 (Cayrel's Star) is an old Population II star located in a distance of 4 kpc in the Galactic Halo. It belongs to the class of ultra-metal-poor stars (Metallicity [Fe/H]=-2.9), especially 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.
Compared to other ultra-metal-poor, r-process enriched stars (as CS22892-052, BD+17°3248) CS31082-001 has higher abundances of the actinides (Th, U), but a surprisingly low Pb abundance.
[edit] 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)
- Cayrel, R.; Hill, V.; Beers, T. C.; Barbuy, B.; Spite, M.; Spite, F.; Plez, B.; Andersen, J.; Bonifacio, P.; François, P.; Molaro, P.; Nordström, B.; Primas, F., Measurement of stellar age from uranium decay, Nature, Volume 409, Issue 6821, pp. 691-692 (2001)
- H. Schatz, R. Toenjes, B. Pfeiffer, T.C. Beers, J.J. Cowan, V. Hill, K.-L. Kratz, Thorium and Uranium Chronometres applied to CS 31082-001, Ap. J.579 (2002) 628 - 638
