ExoMol molecular line lists XXXVI: $X\ {}^2\Pi - X\ {}^2\Pi$ and $A\ {}^2\Sigma^+ - X\ {}^2\Pi$ transitions of SH

TL;DR

This paper presents an extensive line list for the SH molecule, covering multiple electronic states and isotopologues, to aid in astrophysical spectral analysis, especially for exoplanet transmission spectra.

Contribution

The work extends the previous SNaSH line list by including excited electronic states and multiple isotopologues, generated through empirical fitting and ab initio calculations.

Findings

Includes 7686 rovibronic states and 572,145 transitions for $^{32}$SH.

Provides line lists for multiple isotopologues, considering non-Born-Oppenheimer effects.

Data is available in public databases for astrophysical applications.

Abstract

The GYT line list covering rotational, rovibrational and rovibronic transitions of the mercapto radical SH is presented. This work extends and replaces the SNaSH line list [Yurchenko et al., 2018, MNRAS, 478, 270] which covers the ground (electronic) $X$ $^{2}\Pi$ state only. This extension is prompted by the tentative identification of the ultra-violet features of SH as being of importance in the transmission spectrum of the ultra-hot Jupiter exoplanet WASP-121b [Evans et al., 2018, AJ., 156, 283]. This GYT line list model is generated by fitting empirical potential energy, spin-orbit and electronic angular momenta functions to experimentally measured wavelengths within the $X$ $^{2}\Pi$ and $A$ $^{2}\Sigma^{+}$ states and to the $A$ $^{2}\Sigma^{+}$ - $X$ $^{2}\Pi$ band system using ab initio curves as a starting reference point. The fits are compatible with the quoted uncertainty of the experimental data used of $\sim$ 0.03 - 0.3 cm$^{-1}$. The GYT line list covers wavelengths longer than 0.256 $\mu$m and includes 7686 rovibronic states and 572 145 transitions for $^{32}$SH. Line lists for the $^{33}$SH, $^{34}$SH, $^{36}$SH and $^{32}$SD isotopologues are generated including a consideration of non-Born-Oppenheimer effects for SD. The line lists are available from the CDS (http://cdsarc.u-strasbg.fr) and ExoMol (www.exomol.com) data bases.