Abstract:
SDSS J082625.70+612515.10 (V = 11.4; [Fe/H] = −3.1) and SDSS J134144.60+474128.90 (V = 12.4;
[Fe/H] = −3.2) were observed with the SDSS 2.5m telescope as part of the SDSS MARVELS spectroscopic
pre-survey and identified as extremely metal-poor (EMP; [Fe/H] < −3.0) stars during the high-resolution followup using the Hanle Echelle Spectrograph (HESP) on the 2.0-m Himalayan Chandra Telescope. In this paper, the
first science results using HESP, we present a detailed analysis of their chemical abundances. Both stars
exhibit under-abundances in their neutron capture elements, while one of them (SDSS J134144.60+474128.90) is
clearly enhanced in carbon. Lithium was also detected in this star at a level of about A(Li) = 1.95. The spectra
were obtained over a span of 6–24 months, and indicate that both stars could be members of binary systems. We
compare the elemental abundances derived for these two stars along with other carbon-enhanced metal-poor
(CEMP) and EMP stars, in order to understand the nature of their parent supernovae. We find that CEMP-no stars
and EMP-dwarfs show a very similar trend in their lithium abundances at various metallicities. We also find
indications of CEMP-no stars having larger abundances of Cr and Co at given metallicities compared to EMP stars.
