WHAT IS NORMAL AMONG THE A-TYPE STARS

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作者
HILL, GM
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P1 [天文学];
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0704 ;
摘要
Abundances of 15 elements have been determined for 16 early A-type stars, 14 of which are classified as normal. The stars range in upsilon sin i from 5 to 114 km s(-1). Spectrum synthesis has been used to determine the abundances and is shown to be reliable and capable of application to even broader-lined stars. Despite the fact that most of the stars studied are classified as normal, they exhibit a considerable range of abundances. The abundances of most elements scale (at least roughly) with those of iron, which range over more than 0.7 dex among supposedly normal stars. Carbon is probably anti-correlated with iron, while calcium exhibits a more complex behaviour. The range of abundances exhibited by most elements is wide enough that there seems to be a continuous distribution of abundances from those of the Am stars through the normal stars, with the lambda Boo stars defining the low abundance tail of the distribution.
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页码:359 / 368
页数:10
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