On Equilibrium Abundance of C_2 Molecules under Sunspot Conditions

An extensive molecular equilibrium calculation has been performed under sunspot conditions in order to resolve the current dispute on the presence of C_2 lines in the spectrum of sunspots. Equilibrium abundance of C_2 has been computed under the conditions of umbral cores, umbrae and the normal photosphere. As the results, it is found that the umbral cores yield unfavorable environment for C_2 formation. It is concluded that C_2 molecular lines are not likely to be observed in the spectrum of sunspots.