SATELLITES ON LYMAN-ALPHA DUE TO H-H AND H-H+ COLLISIONS

We have experimentally observed satellites on Lyman-alpha arising from radiative collisions of excited atomic hydrogen with unexcited neutra l hydrogen atoms or protons. The wavelength, relative intensity, and s hape of features in the Lyman-alpha wing emitted by a laser-produced p lasma in pure hydrogen agree with new theoretical calculations based o n ab initio H-2(+) and H-2 potentials. These results confirm the ident ification of satellites observed with IUE and HST in the ultraviolet s pectra of hydrogen-rich white dwarfs, and verify the accuracy of the s pectral line shape theory used to determine their effective temperatur es and surface gravities.