Radiative lifetimes and cooling functions for astrophysically important molecules

Abstract

Extensive line lists generated as part of the ExoMol project are used to compute lifetimes for individual rotational, rovibrational and rovibronic excited states, and temperature-dependent cooling functions by summing over all dipole-allowed transitions for the states concerned. Results are presented for SiO, CaH, AlO, ScH, H 2 O and methane. The results for CH 4 are particularly unusual with 4 excited states with no dipole-allowed decay route and several others where these decays lead to exceptionally long lifetimes. These lifetime data should be useful in models of masers and estimates of critical densities, and can provide a link with laboratory measurements. Cooling functions are important in stellar and planet formation.

ExoMol line lists – XV. A new hot line list for hydrogen peroxide

“…An extended line list is provided which contains an additional 8 billion transitions in the 6 000-8 000 cm -1 region with reduced completeness for higher temperature. Radiative lifetimes are also computed via the methodology presented by Tennyson et al (2016a). Figure 1 presents the lifetimes computed for states up to 6 000 cm -1 .…”

EXOCROSS: a general program for generating spectra from molecular line lists

“…1 computed from the 10to10 line list for CH 4 . Examples of ExoMol lifetimes and cooling functions can be found in Tennyson et al (2016a); Melnikov et al (2016) and Mizus et al (2017).…”

ExoMol molecular line lists – XX. A comprehensive line list for H3+

“…We The new line list was used to compute cooling function values for temperatures up to 5000 K. The cooling function is the total energy emitted by a single molecule in one second per unit solid angle. We used the analytical form given by Tennyson et al (2016a) and a version of states file with purely calculated energies (i.e., without replacing them by MARVEL analysis results) to compute the cooling function. Miller et al (2013) when possible (the cooling curve presented in Melin (2006) is valid only in temperature range from 500 to 1800 K, while the one from Miller et al (2013) can be calculated for temperature values 30 -5000 K).…”