  A non-LTE analysis of C I lines at 1.068-1.069 micron was carried out for
selected 46 halo/disk stars covering a wide metallicity range (-3.7 <[Fe/H]<
+0.3), based on the spectral data collected with IRCS+AO188 of the Subaru
Telescope, in order to examine whether and how these strong neutral carbon
lines of multiplet 1 can be exploited for establishing stellar carbon
abundances, especially for very metal-poor stars where CH molecular lines have
been commonly used. These C I lines were confirmed to be clearly visible for
all stars down to [Fe/H] ~ -3.7, from which C abundances could be successfully
determined. The resulting [C/Fe] vs. [Fe/H] diagram revealed almost the same
trend established from previous studies. When the results for individual stars
are compared with the published data collected from various literature, while a
reasonable agreement is seen as a whole, a tendency is observed that our
abundances are appreciably higher than those from CH lines especially for very
metal-poor giants of low gravity. Since the abundances of these C I lines are
subject to rather large non-LTE corrections (typically by several tenths dex)
whose importance progressively grows as the metallicity is lowered, attention
should be paid to how the collisional rates (especially due to neutral
hydrogen) are treated in non-LTE calculations.
