HR: 0830h
AN: P21B-06    [Abstracts]
TI: A Review of Titan's EUV Airglow Leading up to Cassini
AU: * Stevens, M H
EM: stevens@uap2.nrl.navy.mil
AF: Code 7641 E.O. Hulburt Center for Space Research, Naval Research Laboratory, Washington, DC 20375 United States
AU: Bishop, J
EM: jbishop@uap2.nrl.navy.mil
AF: Code 7641 E.O. Hulburt Center for Space Research, Naval Research Laboratory, Washington, DC 20375 United States
AU: Feldman, P D
EM: pdf@pha.jhu.edu
AF: Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218 United States
AB: EUV airglow observations of Titan by the Voyager 1 Ultraviolet Spectrometer (UVS) in 1980 indicated that the spectrum between 52-110 nm was excited primarily by electron impact on N₂. Since then, our understanding of the various emission features contributing to the observed signal has substantially evolved. High resolution electron impact emission laboratory measurements of the important N₂ Carroll-Yoshino (CY) c₄'-X (0,v") bands provided constraints on the predissociation yield of the excited c₄'(0) state. CY(0,v") is radiatively trapped in Titan's atmosphere so that c₄'(0) predissociation is compounded over its optically thin value, increasing the loss to the system. Model results have shown that the depleted CY(0,0) emission near 95.8 nm is redistributed to the more optically thin (0,v">0) bands with some additional loss to the system through extinction. More recently, models of Titan's airglow and observations of the Earth's airglow at high spectral resolution showed the possible significance of many weaker N₂ and N I emissions that were unresolved by the UVS at Titan. In this review, we summarize the current understanding of the Titan EUV airglow up until the arrival of Cassini. We outline some questions that remain unanswered, which include, but are not limited to, a possible misidentification of N₂ CY(0,0) in the Voyager 1 UVS spectra and a possible auroral contribution to the EUV airglow.
DE: 0310 Airglow and aurora
DE: 0358 Thermosphere--energy deposition
DE: 0360 Transmission and scattering of radiation
DE: 6207 Comparative planetology
DE: 6280 Saturnian satellites
SC: Planetary Sciences [P]
MN: 2005 Joint Assembly