Opacities of S-type Stars: The Singlet B 1Π–X 1Σ+, B 1Π–A 1△, and C 1Σ+–X 1Σ+ Band Systems of ZrO

The ZrO B ^1 Π– X ^1 Σ ^+ , B ^1 Π– A ^1 Δ, and C ^1 Σ ^+ – X ^1 Σ ^+ band systems are important opacity sources in the near-infrared and optical spectra of S-type stars. A total of 21 rovibronic bands with v ″ ≤ 7 and $v^{\prime} \leqslant 5$ were observed and fit for the B ^1 Π– X ^1 Σ ^+ transition, five bands for the ^90 ZrO B ^1 Π– A ^1 Δ transition and one band for the ^90 ZrO C ^1 Σ ^+ – X ^1 Σ ^+ transition. All band systems were analyzed using high-temperature, high-resolution emission spectra collected at the National Solar Observatory (Kitt Peak). A modern spectroscopic analysis was performed using the PGOPHER program to provide updated spectroscopic constants. In general, we improve the accuracy of the line positions reported in the literature and slightly extend the vibrational analysis. Equilibrium molecular constants were then derived and combined with new ab initio calculations of transition dipole moment functions to produce line lists with line strengths.