Abstract
THE age of the Galaxy may be estimated from observations of the ratio of stellar abundances of thorium, which has only one long-lived isotope with a half-life comparable to the suspected age of the Galaxy, and neodymium, a stable element. The Th/Nd abundance ratio in a sample of G-dwarf stars of different ages was derived by Butcher1 from the intensities of one Th II and one Nd II absorption line, and indicated a rather young galactic age of 9.6 Gyr. But the Th II line is blended with a Co I line. Here we determine the transition probability of the Co I line by combining radiative lifetime and branching-ratio measurements. We show that the Co I contribution cannot be neglected in deriving Th/Nd ratios. By comparing our results with predictions based on models of galactic chemical evolution, we suggest a revised age of the Galaxy of 15–20 Gyr.
This is a preview of subscription content, access via your institution
Access options
Subscribe to this journal
Receive 51 print issues and online access
$199.00 per year
only $3.90 per issue
Buy this article
- Purchase on Springer Link
- Instant access to full article PDF
Prices may be subject to local taxes which are calculated during checkout
Similar content being viewed by others
References
Butcher, H. R. Nature 328, 127–131 (1987).
Holweger, H. Observatory 100, 155–160 (1980).
Duquette, D. W. & Lawler, J. E. Phys. Rev. A26, 330–334 (1982).
Brault, J. W. J. opt. Soc. Am. 66, 1081 (1976).
Adams, D. L. & Whaling, W. J. opt. Soc. Am. 71, 1036–1038 (1981).
Lawler, J. E. Springer Ser. opt. Sci. 54, 125–140 (1988).
Anders, E. & Grevesse, N. Geochim. cosmochim. Acta 53, 197–214 (1989).
Holweger, H. & Muller, E. A. Solar Phys. 39, 19–30 (1974).
Delbouille, L., Neven, L. & Roland, G. Photometric Atlas of the Solar Spectrum from 3000 to 10000 Ā (Institut d'Astrophysique, Université de Liege, 1973).
Simonsen, H., Worm, T., Jessen, P. & Poulsen, O. Physica Scripta 38, 370–373 (1988).
Palmer, B. A. & Engleman, R. Jr Atlas of the Thorium Spectrum, LA-9615 (Los Alamos National Laboratory, 1983).
Irwin, A. W. Astrophys. J., Suppl. Ser. 45, 621–633 (1981).
Corliss, C. H. & Bozman, W. R. Natn. Bur. Stand. Monogr. 53 (1962).
Kurucz, R. L. Astrophys. J., Suppl. Ser. 40, 1–340 (1979).
Peytremann, E. Astr. Astrophys., Suppl. Ser. 18, 81–133 (1974).
Ward, L., Vogel, O., Arnesen, A., Hallin, P. & Wannstrom, A. Physica Scripta 31, 161–165 (1985).
Arnould, M. & Takahashi, K. Proc. 5th IAP Meeting on Astrophysical Ages and Dating Methods (eds Vangioni-Flam, E., Cassé, M., Audouze, J. & Tran Thanh Van, J.) 325–348 (Editions Frontiéres, Gif-sur-Yvette, 1990).
Mathews, G. J. & Schramm, D. N. Astrophys. J. 324, L67–L70 (1988).
Butcher, H. R. Messenger 51, 12–14 (1988).
Krishnaswamy-Gilroy, K., Sneden, C., Pilachowski, C. A. & Cowan, J. J. Astrophys. J. 327, 298–320 (1988).
Butcher, H. R. Astrophys. J. 199, 710–717 (1975).
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Lawler, J., Whaling, W. & Grevesse, N. Contamination of the Th II line and the age of the Galaxy. Nature 346, 635–637 (1990). https://doi.org/10.1038/346635a0
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1038/346635a0
Comments
By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.
