Line Intensities and Molecular Opacities of the FeHF4Δi–X4ΔiTransition

M. Dulick, C. W. Bauschlicher, Jr., Adam Burrows, C. M. Sharp, R. S. Ram, Peter Bernath
2003 Astrophysical Journal  
We calculate new line lists and opacities for the F^4Δ_i-X^4Δ_i transition of FeH. The 0-0 band of this transition is responsible for the Wing-Ford band seen in M-type stars, sunspots and brown dwarfs. The new Einstein A values for each line are based on a high level ab initio calculation of the electronic transition dipole moment. The necessary rotational line strength factors (Hönl-London factors) are derived for both the Hund's case (a) and (b) coupling limits. A new set of spectroscopic
more » ... tants were derived from the existing FeH term values for v=0, 1 and 2 levels of the X and F states. Using these constants extrapolated term values were generated for v=3 and 4 and for J values up to 50.5. The line lists (including Einstein A values) for the 25 vibrational bands with v≤4 were generated using a merged list of experimental and extrapolated term values. The FeH line lists were use to compute the molecular opacities for a range of temperatures and pressures encountered in L and M dwarf atmospheres. Good agreement was found between the computed and observed spectral energy distribution of the L5 dwarf 2MASS-1507.
doi:10.1086/376791 fatcat:gk3sgp5md5copnrlhezwd4ab2u