Satellites on Lyman Alpha Due to H-H and H-H + Collisions

Abstract

We have experimentally observed satellites on Lyman- alpha arising from radiative collisions of excited atomic hydrogen with unexcited neutral hydrogen atoms or protons. The wavelength, relative intensity, and shape of features in the Lyman- alpha wing emitted by a laser-produced plasma in pure hydrogen agree with new theoretical calculations based on ab initio H ^{+}₂ and H2 potentials. These results confirm the identification of satellites observed with IUE and HST in the ultraviolet spectra of hydrogen-rich white dwarfs, and verify the accuracy of the spectral line shape theory used to determine their effective temperatures and surface gravities.