The authors thank SAO/NASA ADS Astronomy Abstract Service for their deposit authorization. The original publication is available at www.springerlink.com.
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[en] Spectra obtained with the ESO Cassegrain echelle spectrograph are used to determine the abundances of 13 elements in the atmospheres of 20 extreme halo dwarfs. It is found that the alpha elements Mg, Ca, and Ti are overabundant with respect to Fe, that the Cr/Fe ratio is solar at all metallicities, and that Al is overdeficient relative to Mg. The results also indicate that the s elements Sr, Y, and Ba are overdeficient with respect to Fe in stars with Fe/H ratios of less than 2.3, and that for ratios greater than 2.3 the s element abundances relative to Fe are roughly constant (at either solar or higher values).
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Magain, Pierre ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Astrophysique et traitement de l'image
Language :
English
Title :
The chemical composition of the extreme halo stars. I - Blue spectra of 20 dwarfs
