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Paper: Variation in the velocity dispersion of rotationally excited H2
Volume: 348, Astrophysics in the Far Ultraviolet: Five Years of Discovery with FUSE
Page: 445
Authors: Lacour, S.; Ziskin, V.; Oliveira, C.; Hebrard, G.; Andre, M.K.; Ferlet, R.; Vidal-Madjar, A.
Abstract: We present a study of the velocity dispersion of the high rotational levels (J ≥ 2) of H2. The spectrum fitting parameter b increases with the level of excitation, as previously seen by the Copernicus (Spitzer & Cochran 1973) and IMAPS (Jenkins & Peimbert 1997) observatories. In particular, we show with 4σ confidence that for HD192639 it is not possible to fit all J levels with a single b value. We propose a mechanism in which the broadening is due to those molecules that are rotationally excited through the excess energy acquired after their formation on a grain (H2-formation pumping). We show that in a medium with a density of a few 10 cm−3, a broadening of the order of 8 km s−1J = 5 level.
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