Luca Sbordone, Piercarlo Bonifacio, Elisabetta Caffau, Hans-Gunther Ludwig
We report on the result of an ongoing campaign to determine chemical
abundances in extremely metal poor (EMP) turn-off (TO) stars selected from the
Sloan Digital Sky Survey (SDSS) low resolution spectra. This contribution
focuses principally on the largest part of the sample (18 stars out of 29),
observed with UVES@VLT and analyzed by means of the automatic abundance
analysis code MyGIsFOS to derive atmosphere parameters and detailed
compositions. The most significant findings include i) the detection of a
C-rich, strongly Mg-enhanced star ([Mg/Fe]=1.45); ii) a group of Mn-rich stars
([Mn/Fe]>-0.4); iii) a group of Ni-rich stars ([Ni/Fe]>0.2). Li is measured in
twelve stars, while for three upper limits are derived.
View original:
http://arxiv.org/abs/1201.1044
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