The carbon-to-oxygen ratio in halo dwarfs

TLDR: In this article, the authors used four C I lines at 9100 A and the O I triplet at 7770 A to determine C and O abundances in a sample of 34 field halo dwarfs, which span the metallicity range −3.0 ≤ [Fe/H] ≤ −0.8.

Abstract: We have used four C I lines at 9100 A and the O I triplet at 7770 A to determine C and O abundances in a sample of 34 field halo dwarfs, which span the metallicity range −3.0 ≤ [Fe/H] ≤ −0.8. The C I line enable us to obtain, for the first time, C abundances for these metal-deficient stars that are based on atomic, rather than molecular, lines. Additional observations of Fe I and Fe II lines at 4500 and 5200 A have been used to help determine atmosphere parameters of the stars