Reference : The Production of Titan's Ultraviolet Nitrogen Airglow
Scientific congresses and symposiums : Paper published in a book
Physical, chemical, mathematical & earth Sciences : Space science, astronomy & astrophysics
The Production of Titan's Ultraviolet Nitrogen Airglow
Stevens, Michael H. [NRL]
Gustin, Jacques mailto [Université de Liège - ULg > Département d'astrophys., géophysique et océanographie (AGO) > Physique des atmosphères et des environnements planétaires >]
Ajello, J. M. [Jet Propulsion Laboratory]
Evans, J. S. [Computational Physics, Inc]
Meier, R. R. [George Mason University]
Stewart, A. I. F. [University of Colorado]
Esposito, L. W. [University of Colorado]
McClintock, W. E. [University of Colorado]
Stephan, A. W. [NRL)]
AAS/Division for Planetary Sciences Meeting Abstracts #42
American Astronomical Society, DPS meeting #42
october 2010
[en] The Cassini Ultraviolet Imaging Spectrograph (UVIS) observed Titan's dayside limb on 22 June, 2009, obtaining high quality extreme ultraviolet (EUV) and far ultraviolet (FUV) spectra from a distance of only 60,000 km (23 Titan radii). The observations reveal the same EUV and FUV emissions arising from photoelectron excitation and photofragmentation of molecular nitrogen (N[SUB]2[/SUB]) on Earth but with the altitude of peak emission much higher on Titan near 1000 km altitude. In the EUV, emission bands from the photoelectron excited N[SUB]2[/SUB] Carroll-Yoshino c[SUB]4[/SUB]'-X system and N I and N II multiplets arising from photofragmentation of N[SUB]2[/SUB] dominate, with no detectable c[SUB]4[/SUB]'(0,0) emission near 958 Å, contrary to many interpretations of the lower resolution Voyager 1 Ultraviolet Spectrometer data. The FUV is dominated by emission bands from the N[SUB]2[/SUB] Lyman-Birge-Hopfield a-X system and additional N I multiplets. We also identify several N[SUB]2[/SUB] Vegard-Kaplan A-X bands between 1500-1900 Å, two of which are located near 1561 and 1657 Å where C I multiplets were previously identified from a separate UVIS disk observation. We compare these limb emissions to predictions from a terrestrial airglow model adapted to Titan that uses a solar spectrum appropriate for these June, 2009 observations. Volume production rates and limb radiances are calculated, including extinction by methane and allowance for multiple scattering within the readily excited c[SUB]4[/SUB]'(0,v') system, and compared to UVIS observations. We find that for these airglow data only emissions arising from processes involving N[SUB]2[/SUB] are present.

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