Discovery of HE 1523–0901, a Strongly r-Process-enhanced Metal-poor Star with Detected Uranium
Abstract
We present age estimates for the newly discovered, very r-process-enhanced metal-poor star HE 1523-0901 ([Fe/H] = -2.95) based on the radioactive decay of Th and U. The bright (V = 11.1) giant was found among a sample of bright metal-poor stars selected from the Hamburg/ESO Survey. From an abundance analysis of a high-resolution (R = 75,000) VLT/UVES spectrum, we find HE 1523-0901 to be strongly overabundant in r-process elements ([r/Fe] = 1.8). The abundances of heavy neutron-capture elements (Z > 56) measured in HE 1523-0901 match the scaled solar r-process pattern extremely well. We detect the strongest optical U line at 3859.57 Å. For the first time, we are able to employ several different chronometers, such as the U/Th, U/Ir, Th/Eu, and Th/Os ratios to measure the age of a star. The weighted average age of HE 1523-0901 is 13.2 Gyr. Several sources of uncertainties are assessed in detail.
Additional Information
© 2007 American Astronomical Society. Received 2006 November 21, accepted for publication 2007 March 15. Published 2007 April 11. We thank the ESO staff for carrying out the VLT-UT2 observations and reducing the data. Allocation of VLT Director's Discretionary Time is gratefully acknowledged. We are indebted to V. Hill for providing a spectrum of CS 31082-001 and B. Plez for providing his newly compiled CH line list. Fruitful discussions on spectrum synthesis calculations with W. Hayek and C. Sneden are acknowledged. This research made extensive use of the Vienna Atomic Line Database (VALD). A. F. and J. E. N. acknowledge support from the Australian Research Council under grants DP0342613 and DP0663562. N. C. is a Research Fellow of the Royal Swedish Academy of Sciences supported by a grant from the Knut and Alice Wallenberg Foundation. He acknowledges support by Deutsche Forschungsgemeinschaft through grants Ch 214/3 and Re 353/44. T. C. B. is supported by the US National Science Foundation under grant AST 04-06784 as well as from grant PHY 02-16783 (Physics Frontier Center/JINA). Facilities: VLT:Kueyen(UVES), Magellan:Clay(MIKE).Attached Files
Published - FREapjl07.pdf
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Additional details
- Eprint ID
- 16647
- Resolver ID
- CaltechAUTHORS:20091110-141529764
- Australian Research Council
- DP0342613
- Australian Research Council
- DP0663562
- Knut and Alice Wallenberg
- Deutsche Forschungsgemeinschaft
- Ch 214/3
- Deutsche Forschungsgemeinschaft
- Re 353/44
- NSF
- AST 04-06784
- NSF
- PHY 02-16783
- Created
-
2009-11-13Created from EPrint's datestamp field
- Updated
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2021-11-08Created from EPrint's last_modified field