S20A0101abst
S20A0101
We propose to obtain high-resolution near infrared spectra of Carbon-Enhanced Metal-Poor (CEMP) stars, including dwarf carbon stars, with IRD to measure chemical abundances from atomic and molecular lines. As the origins of the carbon excess in these stars, several models have been proposed: supernova explosions of early generation massive stars that eject little amounts of Fe, mass transfer from companion AGB stars in binary systems, etc.. To distinguish these possibilities, measured abundance patterns of elements, in particular the oxygen abundance, are required. Near infrared spectra with IRD will provide unique opportunity to determine oxygen abundances from molecular lines (CO and/or OH) and light elements (e.g., Na, Al, K) from atomic lines. The target with highest priority in this program is the dwarf carbon star G77-61, which has [Fe/H]=β4.0 and large excesses of C and N. Abundance ratios of O and other light elements will be useful to constrain the origins of not only G77-61, but also of other dwarf carbon stars recently identified by SDSS. We will apply similar observation to a fainter dwarf carbon star discovered with SDSS and/or CEMP stars that would records the yields of first stars.
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