Abstract
We report the first observation of Lyα pumped molecular hydrogen emission lines in planetary nebulae. The H2 emission observed in the ultraviolet spectra of NGC 6853 and NGC 3132 can be explained by excitation of vibrationally hot H2 by Lyα photons. Constraints are placed on the nebular Lyα emission profile, as well as the molecular hydrogen temperature, column density, and turbulent motion. These parameters are similar for the two nebulae, pointing to similar physical conditions in these objects. The rovibrational cascade following Lyα pumping is predicted to have low surface brightness signatures in the visible and near-infrared.
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