2002/07/01 by Philippe F. Weck, P. F. Weck, A. Schweitzer +3 · 4 citations
Chemistry · Earth and Planetary Sciences · Physics and Astronomy · #Advanced Chemical Physics Studies #Atmospheric Ozone and Climate #Spectroscopy and Laser Applications #astro-ph
paper · pdf · doi:10.1086/345524
published as Astrophys.J. 584 (2003) 459-464 · 9 pages, 8 figures
arxiv created 2002/07/01 · openalex publication_date 2003/02/10 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
The opacity due to photodissociation of 24MgH is investigated in the atmospheres of cool stars. The lowest two electronic transitions A 2Pi -- X 2Sigma+ and B' 2Sigma+ -- X 2 Sigma+ are considered where the cross sections for the latter were published previously (Weck, Stancil, & Kirby 2002) while the former are presented in this work. Model atmospheres calculated with the PHOENIX code are used to investigate the effect of the photodissociation opacity on spectra of cool stars. The A -- X photodissociation cross sections are obtained using a combination of ab initio and experimentally derived potential curves and dipole transition moments. Partial cross sections have been evaluated over the accessible wavelength range 1770-4560 Angstrom for all rotational transitions from the vibrational levels v''=0-11. Assuming a Boltzmann distribution of the rovibrational levels of the X 2Sigma+ state, LTE photodissociation cross sections are presented for temperatures between 1000 and 5000 K. Shape resonances, arising from rotational predissociation of quasi-bound levels of the A 2Pi state near threshold, characterize the LTE photodissociation cross sections. A sum rule is proposed as a check on the accuracy of the photodissociation calculations.