Molecular column densities in selected model atmospheres

Molecular column densities are presented for 35 molecules in a variety of cool stellar model atmospheres. From an examination of the predicted column densities, we draw the following conclusions: (1) OH might be visible in carbon stars which have been generated from triplet-α burning, but will be absent from carbon stars generated from the CNO bi-cycle. (2) The TiO/ZrO ratio shows small but interesting variations as C/O is changed and as the effective temperature is changed. (3) The column density of silicon dicarbide (SiC2) is sensitive to abundance, temperature, and gravity; hence, all relationships between the strength of SiC2 and other stellar parameters will show appreciable scatter. There is, however, a substantial luminosity effect present in the SiC2 column densities. (4) Unexpectedly, SiC2 is anticorrelated with C2. (5) The presence of SiC2 in a carbon star allows us to eliminate the possibility that these stars are both ''hot'' (T/sub eff/ greater than or equal to 3000 K) and have been produced through the CNO bi-cycle (so that C/H<solar)