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Fig. 11

image

Centre-to-limb variation of the Ca lines in the [6160,6170] Å region and the 8662 Å Ca II triplet line. The atmospheric model used was MACKKL. In order to get the best fit for the observed intensity profile at μ = 1.0, calcium abundances and macroturbulent velocities were (A(Ca), vmacro) = (6.28 dex, 1.6 m s−1) for the LTE and (6.26 dex, 1.9 m s−1) for the NLTE synthetic profiles. The 8662 Å line produces an emission core in LTE due to the increase in temperature at τ approximately −4 in the MACKKL model; in order to avoid over-plotting, the emission cores at μ = 0.6 and 0.2 werecut. The Ca II triplet line was also modelled using the Kurucz solar model atmosphere. LTE-Kurucz profiles are the long dashed lines and NLTE-Kurucz profiles are the dot-dashed lines.

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