THE C-2 BALLIK-RAMSAY TRANSITIONS IN CARBON STARS

The bands of C2 are an important source of opacity in the near-infrared spectral region of carbon stars. In the 2 fim spectral region, the Δυ = -1 and -2 transitions of the Ballik-Ramsay b 3Σg--a 3Πu system are especially important. A general method for calculating highly accurate transition parameters of the Ballik-Ramsay band is presented. This method allows the easy calculation of the satellite lines and the forbidden lines resulting from the perturbation of the upper b 3Σg- state by the X 1Σ0+ state. Included in the calculation is the effect of the isotopic molecules 12C2, 12C13C, and 13C2. Three consistency tests of the calculated strengths are presented. A comparison of synthetic spectra is made with an observed spectrum of WZ Cas in the 3940 cm-1 spectral region.