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He 584 Å dayglow at Neptune
Author(s) -
Parkinson Christopher D.,
McConnell John C.,
Sandel Bill R.,
Yelle Roger V.,
Broadfoot A. Lyle
Publication year - 1990
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/gl017i010p01709
Subject(s) - neptune , astrobiology , astronomy , geology , environmental science , physics , planet
The Voyager 2 Ultraviolet Spectrometer measured the emission intensity of the He resonance line at 584 Å to be0.34 ‐ 0.15 + 0.2R on the day side of Neptune. Our calculations of the He 584 Å intensity at Neptune using partial frequency redistribution and inhomogeneous atmospheric models show that the product of the volume mixing ratio (mole fraction), f H e , and the eddy diffusion coefficient at the homopause, K h , is f He K h = 10 7 cm 2 s −1 with upper and lower bounds to the uncertainty of about a factor of 3 and 9, respectively. If f He is taken as the current Infrared Interferometer Spectrometer working value, f He = 0.19, then K h = 5×10 7 cm 2 s −1 with a similar uncertainty. This range of K overlaps that obtained from analysis of the hydrocarbon distributions on Neptune (Broadfoot et al., 1989).