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Table 3:

Derived abundances of oxygen and carbon for the sample of 43 halo stars. The resulting [C/H], [O/H] and [C/O] abundance ratios derived in this study are also given, both for LTE and non-LTE (using our adopted abundance corrections obtained with and without including collisions with H  I atoms, respectively). In the non-LTE case, S$_{\rm H}$ indicates the scaling factor regulating the efficiency of the collisions with neutral H atoms via the Drawin formula. The differential abundances ([C/O], [O/H], [Fe/H]) with respect to the Sun were derived assuming$^{\rm 1}$ $\log {\rm (C/H)_{\odot}} + 12 = 8.39$, $\log {\rm (O/H)_{\odot}} + 12 = 8.66$, and $\log {\rm (Fe/H)_{\odot}} + 12 = 7.45$.
ID $\log\epsilon_{\rm C}$ $\log\epsilon_{\rm O}$ [C/H] [C/H] [C/H] [O/H] [O/H] [O/H] [C/O] [C/O] [C/O]
  (LTE) (LTE) (LTE) ( $S_{\rm H}=0$) ( $S_{\rm H}=1$) (LTE) ( $S_{\rm H}=0$) ( $S_{\rm H}=1$) (LTE) ( $S_{\rm H}=0$) ( $S_{\rm H}=1$)
UVES (2001)                      
BD-13$^{\circ}$3442 6.14 6.89 -2.25 -2.62 -2.56 -1.77 -2.39 -2.11 -0.48 -0.23 -0.45
CD-30$^{\circ}$18140 6.73 7.58 -1.66 -1.93 -1.84 -1.08 -1.27 -1.22 -0.58 -0.66 -0.62
CD-35$^{\circ}$14849 6.38 7.05 -2.01 -2.30 -2.22 -1.61 -1.99 -1.81 -0.40 -0.31 -0.41
CD-42$^{\circ}$14278 6.54 7.28 -1.85 -2.07 -1.97 -1.38 -1.55 -1.47 -0.47 -0.52 -0.50
G011-044 6.58 7.37 -1.81 -2.03 -1.94 -1.29 -1.47 -1.40 -0.52 -0.56 -0.54
G013-009 6.48 7.19 -1.91 -2.25 -2.17 -1.47 -1.83 -1.73 -0.44 -0.42 -0.44
G018-039 7.23 8.04 -1.16 -1.40 -1.29 -0.62 -0.84 -0.77 -0.54 -0.56 -0.52
G020-008 6.54 7.30 -1.85 -2.11 -2.01 -1.36 -1.63 -1.51 -0.49 -0.48 -0.50
G024-003 6.65 7.56 -1.74 -1.97 -1.87 -1.10 -1.30 -1.24 -0.64 -0.67 -0.63
G029-023 6.82 7.71 -1.57 -1.84 -1.75 -0.95 -1.16 -1.11 -0.62 -0.68 -0.64
G053-041 7.01 7.78 -1.38 -1.66 -1.53 -0.88 -1.09 -1.03 -0.50 -0.57 -0.50
G064-012 5.67 6.45 -2.72 -3.17 -3.09 -2.21 -3.10 -2.71 -0.51 -0.07 -0.38
G064-037 5.71 6.42 -2.68 -3.13 -3.05 -2.24 -3.12 -2.70 -0.44 -0.01 -0.35
G066-030 6.91 7.90 -1.48 -1.76 -1.66 -0.76 -1.03 -0.96 -0.72 -0.73 -0.70
G126-062 6.94 7.86 -1.45 -1.72 -1.62 -0.80 -1.04 -0.98 -0.65 -0.68 -0.64
G186-026 6.15 6.75 -2.24 -2.56 -2.49 -1.91 -2.47 -2.20 -0.33 -0.09 -0.29
HD 106038 7.38 8.05 -1.01 -1.28 -1.14 -0.61 -0.82 -0.75 -0.40 -0.46 -0.39
HD 108177 6.90 7.75 -1.49 -1.73 -1.63 -0.91 -1.11 -1.04 -0.58 -0.62 -0.59
HD 110621 7.02 7.89 -1.37 -1.65 -1.54 -0.77 -0.99 -0.94 -0.60 -0.66 -0.60
HD 140283 6.27 6.99 -2.12 -2.40 -2.32 -1.67 -1.91 -1.81 -0.45 -0.49 -0.51
HD 160617 6.71 7.39 -1.68 -1.97 -1.87 -1.27 -1.47 -1.42 -0.41 -0.50 -0.45
HD 179626 7.54 8.38 -0.85 -1.11 -0.98 -0.28 -0.51 -0.45 -0.57 -0.60 -0.53
HD 181743 6.76 7.58 -1.63 -1.84 -1.74 -1.08 -1.24 -1.18 -0.55 -0.60 -0.56
HD 188031 6.84 7.69 -1.55 -1.81 -1.72 -0.97 -1.18 -1.12 -0.58 -0.63 -0.60
HD 193901 7.41 8.17 -0.98 -1.19 -1.06 -0.49 -0.65 -0.58 -0.49 -0.54 -0.48
HD 194598 7.44 8.15 -0.95 -1.22 -1.11 -0.51 -0.75 -0.68 -0.44 -0.47 -0.43
HD 215801 6.32 7.22 -2.07 -2.37 -2.29 -1.44 -1.72 -1.61 -0.63 -0.65 -0.68
LP815-43 6.16 6.71a -2.23 -2.63 -2.56 -1.95 -2.70 -2.36 -0.28 +0.07 -0.20
UVES (2004)                      
CD-24 17504b 5.81 6.24 -2.58 -2.91 -2.84 -2.42 -3.25 -2.87 -0.16 +0.34 +0.03
CD-71 1234 6.28 7.03 -2.11 -2.40 -2.33 -1.63 -2.04 -1.86 -0.48 -0.36 -0.47
CS 22943-0095 6.56 7.33 -1.83 -2.13 -2.05 -1.33 -1.66 -1.52 -0.50 -0.47 -0.53
G004-037 6.26 7.16 -2.13 -2.44 -2.36 -1.50 -1.96 -1.75 -0.63 -0.48 -0.61
G048-029c 6.01 6.81 -2.38 -2.70 -2.64 -1.85 -2.48 -2.18 -0.53 -0.22 -0.46
G059-027 6.81 7.60 -1.58 -1.84 -1.74 -1.06 -1.24 -1.18 -0.52 -0.60 -0.56
G126-052 6.42 7.15 -1.97 -2.26 -2.18 -1.51 -1.83 -1.69 -0.46 -0.43 -0.49
G166-054 6.03 6.91 -2.36 -2.72 -2.64 -1.75 -2.33 -2.05 -0.61 -0.39 -0.59
HD 84937 6.53 7.27 -1.86 -2.15 -2.07 -1.39 -1.64 -1.56 -0.47 -0.51 -0.51
HD 338529 6.46 7.24 -1.93 -2.25 -2.17 -1.42 -1.77 -1.63 -0.51 -0.48 -0.54
LP635-014 6.39 7.06 -2.00 -2.33 -2.25 -1.60 -2.03 -1.85 -0.40 -0.30 -0.40
LP651-004 6.08 7.04 -2.31 -2.99 -2.58 -1.62 -2.21 -1.93 -0.69 -0.44 -0.65
MIKE (2003)                      
G041-041 5.96 6.74 -2.43 -2.85 -2.76 -1.92 -2.54 -2.25 -0.51 -0.31 -0.51
G048-029c 6.11 6.80 -2.28 -2.66 -2.59 -1.86 -2.50 -2.20 -0.42 -0.16 -0.39
G084-029 6.06 6.87 -2.33 -2.72 -2.63 -1.79 -2.33 -2.08 -0.54 -0.39 -0.55
LP831-070b <5.77 <6.53 <-2.62 <-3.01 <-2.93 <-2.13 <-2.95 <-2.54 - - -
$^{\rm 1}$ Asplund et al. (2005).

a As discussed by Fabbian et al. (2006), the oxygen determination by Nissen et al. (2002) for this stars is more reliable than that derived from the UVES 2001 spectra and was therefore adopted here.

b Since the O  I  lines are barely visible in these two stars, spectral synthesis and chi square minimization (see text) of the profiles of the O  I  triplet lines were used in order to constrain their oxygen content.

c This star was observed in both UVES (2004) and MIKE (2003) runs. The C and O abundances derived in the two cases using the respective atmospheric parameters for the two sets of spectra are shown here, while their mean was adopted in Figs. 5-8.


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