Cayrel's Star
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Cetus |
| Right ascension | 01h 29m 30.31s |
| Declination | -16° 08' 5.51" |
| Apparent magnitude (V) | 11.7 |
| Other designations | |
BD -16°251, CS31082-001 | |
BPS CS31082-0001, named Cayrel's Star,[1] 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), 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.
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
- Ultra low metallicity / ultra metal poor stars
References
- 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
External links
- SIMBAD-Entry (SIMBAD)
- arXiv: Measurement of stellar age from uranium decay, R. §Cayrel et al.
- R-Process Cosmo-Chronometers