CONTAMINATION OF THE TH-II LINE AND THE AGE OF THE GALAXY

被引:36
作者
LAWLER, JE
WHALING, W
GREVESSE, N
机构
[1] CALTECH,PASADENA,CA 91125
[2] UNIV LIEGE,INST ASTROPHYS,B-4200 COINTE OUGREE,BELGIUM
关键词
D O I
10.1038/346635a0
中图分类号
O [数理科学和化学]; P [天文学、地球科学]; Q [生物科学]; N [自然科学总论];
学科分类号
07 ; 0710 ; 09 ;
摘要
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. © 1990 Nature Publishing Group.
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收藏
页码:635 / 637
页数:3
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