Presence of LaO, ScO and VO Molecular Lines in Sunspot Umbral Spectra

Abstract

High-resolution Fourier Transform Spectrometer sunspot umbral spectra of the National Solar Observatory/National Optical Astronomy Observatory at Kitt Peak were used to detect rotational lines from 19 electronic transition bands of the molecules LaO, ScO and VO, in the wavenumber range of 11 775 to 20 600 cm−1. The presence of lines from the following transitions is confirmed: A2Πr1/2 – X2Σ+(0, 0; 0, 1), A2Πr3/2 – X2Σ+(1, 0), B2Σ+ – X2Σ+(0, 0; 0, 1; 1, 0) and C2Πr1/2 – A′2Δr3/2(0, 0; 1, 1) of LaO; A2Πr3/2 – X2Σ+(0, 0), A2Πr1/2 – X2Σ+(0, 0) and B2Σ+ – X2Σ+(0, 0) of ScO; and C4Σ− – X4Σ−(0, 1; 1, 0; 0, 2) and (2, 0) of VO. However, the presence of A2Πr3/2 – X2Σ+(0, 0) and C2Πr3/2 – A′2Δr5/2(0, 0; 1, 1) of LaO and C4Σ− – X4Σ−(0, 0) of VO are found to be doubtful because the lines are very weak, and detections are difficult owing to heavy blending by strong rotational lines of other molecules. Equivalent widths are measured for well-resolved lines and, thereby, the effective rotational temperatures are estimated for the systems for which the presence is confirmed.