Manganese and carbon lines as temperature indicators

Selected hyperfine structure broadened lines of various excitations and the carbon line at 5380 Å are tested as temperature diagnostics for photospheric heterogeneities. This is done by comparing the observed center-to-limb variation of the equivalent widths of these lines with predictions by several proposed models of homogeneous type. Model 10 (Elste, 1968), which also explains the limb-darkening of the continuum in the same spectral range, provides a better basis for the analysis of heterogeneities at different photospheric levels than other recent reference models.