Discovery of Lyman-alpha Pumped Molecular Hydrogen Emission in the Planetary Nebulae NGC 6853 and NGC 3132

Abstract

We report the first observation of Ly$\alpha$ pumped molecular hydrogen emission lines in planetary nebulae. The H${}_2$ emission observed in the ultraviolet spectra of NGC 6853 and NGC 3132 can be explained by excitation of vibrationally hot H${}_2$ by Ly$\alpha$ photons. Constraints are placed on the nebular Ly$\alpha$ 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 ro-vibrational cascade following Ly$\alpha$ pumping is predicted to have low surface brightness signatures in the visible and near infrared.

arXiv commentemulate ApJ, 9 pages, 8 figures, 9 tables, ApJ accepted

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Cited by in corpus (12)

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• A Low-Mass H2 Component to the AU Microscopii Circumstellar Disk
• A Cometary Bow Shock and Mid-Infrared Emission Variations Revealed in Spitzer Observations of HD 34078 and IC 405
• The MUSE view of the planetary nebula NGC 3132
• Lyman-$\alpha$ feedback prevails at Cosmic Dawn: Implications for the first galaxies, stars, and star clusters
• H${}_2$ Fluorescence in M Dwarf Systems: A Stellar Origin
• The Far Ultraviolet Spectral Signatures of Formaldehyde and Carbon Dioxide in Comets
• Molecular and Atomic Excitation Stratification in the Outflow of the Planetary Nebula M27
• The Orion fingers: H${}_2$ temperatures and excitation in an explosive outflow
• Metal Absorption Profiles from the Central Star of the Planetary Nebula M27 (NGC 6853, PN G060.8-03.6, the Dumbbell) -- Photospheric and Nebular Line Identifications