ExoMol line lists -- LII. Line Lists for the Methylidyne Cation (CH+)

TL;DR

This paper presents comprehensive rovibronic line lists for the methylidyne cation (CH+), combining empirical data and ab initio calculations to improve accuracy for astrophysical applications up to 5000 K.

Contribution

It provides the first extensive line lists for CH+ using a combination of empirical and theoretical methods, including MARVEL analysis and empirical corrections.

Findings

Line list contains 1505 states and 34194 transitions.

Excellent agreement with laboratory and astronomical spectra.

Available from the ExoMol database for astrophysical modeling.

Abstract

Comprehensive and accurate rovibronic line lists for the X $^{1}\Sigma^{+}$ and A $^{1}\Pi$ states of $^{12}$C$^{1}$H$^{+}$ and $^{13}$C$^{1}$H$^{+}$ which should be applicable up to temperatures of 5000 K are presented. Available empirical potential energy curves and high-level ab initio dipole and transition dipole moment curves are used with the program LEVEL to compute rovibronic energy levels and Einstein $A$ coefficients. $\Lambda$-doubling is incorporated into the energy levels and $A$-coefficients involving the A $^{1}\Pi$ state using an empirical method. For $^{12}$C$^{1}$H$^{+}$, line positions are improved by using both laboratory and astronomical observational spectra as input to the MARVEL procedure. The $^{12}$C$^{1}$H$^{+}$ line list contains 1505 states and 34194 transitions over the frequency range of 0 - 33010 cm$^{-1}$ ($\lambda > 300$ nm). Comparisons with observed astronomical and laboratory spectra give very good agreement. The PYT CH$^{+}$ line lists and partition functions are available from the ExoMol database at www.exomol.com.