Identification of AlF Molecular Lines in Sunspot Umbral Spectra

Abstract

High resolution FTS sunspot umbral spectra from NSO/Kitt Peak were used to detect rotational lines due to 11 electronic transitions of the molecule AlF, in the wavelength region 4400 9000 Å. The presence of lines due to bands C A (0,0), (0,1), (0,2) and (1,2), D A (0,0) and (0,1), F A (0,0), G A (0,0), and F B (0,0) is confirmed. Further, the presence of lines due to C A (1,0) and (1,1) transitions is treated as doubtful because of heavy blending in the region, by rotational lines of TiO. Among the identified lines, those which are well resolved were selected for measurement of equivalent widths. The measured values for the bands D A (0,0) and F A (0,0) were used to estimate the respective effective rotational temperatures to be 1240 ± 120 K and 2390 ± 400 K.