Evolution of sunspots seen in molecular lines. I

Abstract

Equivalent-width calculations are conducted for lines of C2, MgH, and TiO relevant to photospheric and sunspot model atmospheres to determine the effects of magnetic field strength on line intensities. Sunspot models with different magnetic field strengths and a photospheric model by Holweger and Mueller (1974) are employed with a given data set. The partial pressures of the molecules C2, MgH, and TiO are delineated for each model, and the calculated equivalent widths are listed. It is shown that the three lines are important for understanding sunspot atmospheres and should be examined at both the spot and the photosphere to understand the evolution of sunspots. The model atmospheres developed by Sobotka (1985) and Maltby et al. (1986) for umbrae of varying sizes are employed to study sunspot evolution in terms of C2, MgH, and TiO. It is shown that changes in model atmospheres can be discerned by observing photospheres and sunspots via certain bands of MgH, C2, and TiO