Yan, M.Sadeghpour, H. R.Dalgarno, A.2019-09-241998Yan, M., H. R. Sadeghpour, and A. Dalgarno. 1998. “Photoionization Cross Sections of He and H2.” The Astrophysical Journal 496 (2): 1044–50. https://doi.org/10.1086/305420.0004-637X1538-4357http://nrs.harvard.edu/urn-3:HUL.InstRepos:41397396We combine accurate measurements at low energies and theoretical calculations at high energies to construct sets of photoionization cross sections of He and H-2 that should be reliable at all energies. We control the accuracy of the recommended cross section data by ensuring that they satisfy a range of oscillator strength sum rules. We provide accurate analytic formulae for the photoionization cross sections that have the proper asymptotic form. At high frequencies the cross sections for H-2 are 2.8 times those for H.en-USJournal Article2019-09-2410.1086/305420