Resonant Molecular Opacity in Stellar Atmospheres
Jackson White, University of Texas at Austin
Spectral line shapes describe the opacity distribution from bound-bound atomic transitions, and are sensitive to the density, temperature, and composition of the surrounding environment. Theoretical line profiles are a valuable diagnostic tool in high energy density (HED) plasmas including both astrophysical objects and laboratory experiments. Recent discrepancies between theoretical and measured opacities[1,2] at the Sandia Z-Machine have prompted a renewed search for possible theoretical inadequacies in opacity modeling, including spectral line broadening. A known deficiency of line shape theory is its poor treatment of close atomic collisions[3]. In this poster we present a novel approach for modeling 'resonant molecules', or transient unbound atomic close collisions which temporarily induce molecular-like structure, in the calculation of spectral line profiles. We show resonant-H2+ spectral lines calculated with this method which are immediately applicable to hydrogen stellar atmospheres. Additionally we discuss the physical advancements of this approach which make it useful for a wide range of conditions and applications, including continuum lowering. [1] Bailey, J.E. et al., Nature, 2015 [2] Schaeuble, M.A. et al., ApJ, 2019 [3] Cho, P.B. et al., ApJ, 2022