TY - JOUR
T1 - Vibrationally excited H2 in the outer planets thermosphere
T2 - Fluorescence in the Lyman and Werner bands
AU - Majeed, Tariq
AU - McConnell, John C.
AU - Yelle, Roger V.
N1 - Funding Information:
ported from JPL contract 957763 under NASA contract NAGW-918 to the University of Arizona. TM also wishes to acknowledge partial support for this work by the Space and Terrestrial Physics Laboratory (STPL ) of the Institute of Space and Terrestrial Science (ISTS) in Ontario, Canada. JCM wishes to thank the Natural Science and Engineering Research Coun-sil (NSERC) of Canada for continuing support. JCM would also like to thank the Institut d’Astrophysique Spatial, CNRS, at Verrieres le Buisson for support.
PY - 1991/11
Y1 - 1991/11
N2 - We have considered the impact of fluorescence of ground state H2 on the distribution of the vibrational levels of Ha in the upper atmospheres of Jupiter and Saturn for non-auroral latitudes. For v ≥ 3, for the conditions studied, this is the most important source of vibrationally excited H2 compared with other sources, such as photoelectron induced fluorescence, dissociative recombination of H+3 ions, and direct vibrational excitation of H2 by photoelectron impact. Combining the Voyager limb observations of H2 band emissions on Saturn, theoretical calculations of the H2 fluoresence distribution, and column constraints of Jovian H2 airglow, we estimate that some of the higher vibrational levels may have effective temperatures > 3000 K on both Jupiter and Saturn. In turn, the vibrational population of v ≥ 4 levels are sufficiently increased by the fluorescence source that the chemical sink for the ionization is enhanced. As a result, ionospheric densities may be greatly affected. We also show that the vertical ion flows induced by horizontal neutral winds or dynamo electric fields must play some role in maintaining the plasma peaks at higher altitudes.
AB - We have considered the impact of fluorescence of ground state H2 on the distribution of the vibrational levels of Ha in the upper atmospheres of Jupiter and Saturn for non-auroral latitudes. For v ≥ 3, for the conditions studied, this is the most important source of vibrationally excited H2 compared with other sources, such as photoelectron induced fluorescence, dissociative recombination of H+3 ions, and direct vibrational excitation of H2 by photoelectron impact. Combining the Voyager limb observations of H2 band emissions on Saturn, theoretical calculations of the H2 fluoresence distribution, and column constraints of Jovian H2 airglow, we estimate that some of the higher vibrational levels may have effective temperatures > 3000 K on both Jupiter and Saturn. In turn, the vibrational population of v ≥ 4 levels are sufficiently increased by the fluorescence source that the chemical sink for the ionization is enhanced. As a result, ionospheric densities may be greatly affected. We also show that the vertical ion flows induced by horizontal neutral winds or dynamo electric fields must play some role in maintaining the plasma peaks at higher altitudes.
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U2 - 10.1016/0032-0633(91)90085-O
DO - 10.1016/0032-0633(91)90085-O
M3 - Article
AN - SCOPUS:0007505686
SN - 0032-0633
VL - 39
SP - 1591
EP - 1606
JO - Planetary and Space Science
JF - Planetary and Space Science
IS - 11
ER -