S-type Stars: LaO Line List for the B2Σ+–X2Σ+ Band System

Abstract

Abstract LaO bands are a characteristic feature in the spectrum of cool S-type stars. La is made primarily by the s-process during the asymptotic giant branch phase of stellar evolution. The B2Σ+–X2Σ+ and A2Π–X2Σ+ band systems can be used to determine the La abundances in cool S stars. The bands of the B2Σ+–X2Σ+ with v ′ and v ′ ′ ≤ 5 have been rotationally analyzed from an emission spectrum from a carbon furnace. Line strengths are calculated using an ab initio transition dipole function, corrected using experimental lifetimes. We provide a line list for the B2Σ+–X2Σ+ band system that can be used to determine La abundances.