COMPUTATION OF COLLISION-INDUCED ABSORPTION BY SIMPLE MOLECULAR COMPLEXES, FOR ASTROPHYSICAL APPLICATIONS
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Date
2012
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Publisher
Ohio State University
Abstract
The interaction-induced absorption by collisional pairs of H${_2}$ molecules is an important opacity source in the atmospheres of various types of planets and cool stars, such as late stars, low-mass stars, brown dwarfs, cool white dwarf stars, the ambers of the smaller, burnt out main sequence stars, exoplanets, etc., and therefore of special astronomical interest. The emission spectra of cool white dwarf stars differ significantly in the infrared from the expected blackbody spectra of their cores, which is largely due to absorption by collisional H${_2}$--H${_2}$, H${_2}$--He, and H${_2}$--H complexes in the stellar atmospheres. Using quantum-chemical methods we compute the atmospheric absorption from hundreds to thousands of kelvin. Laboratory measurements of interaction-induced absorption spectra by H${_2}$ pairs exist only at room temperature and below. We show that our results reproduce these measurements closely so that our computational data permit reliable modeling of stellar atmosphere opacities even for the higher temperatures. First results for H$_2$--He complexes have already been applied to astrophysical models and have shown great improvements in these models.
Description
Author Institution: Department of Physics, The University of Texas at Austin, Austin, TX 78712; Department of Chemistry, Michigan State University, East Lansing, MI 48824