S-type Stars: Line List for the A2Π–X2Σ+ Band System of LaO

Abstract LaO bands are found in the spectra of cool S-type stars. The bands of the A2Π–X2Σ+ transition with v ′ ≤ 3 and v″ ≤ 4 are rotationally analyzed, providing spectroscopic constants for the A2Π state. Line strengths are calculated using an ab initio transition dipole moment function, and radiative lifetimes for the A2Π state have also been computed. A line list for the A2Π–X2Σ+ transition of LaO is provided and can be used to determine LaO stellar abundances.