Title

Titan Airglow Spectra From Cassini Ultraviolet Imaging Spectrograph (Uvis): Euv Analysis

Abstract

We present the first UV airglow observations of Titan's atmosphere by the Ultraviolet Imaging Spectrograph (UVIS) on Cassini. Using one spectral channel in the EUV from 561-1182 Å and one in the FUV from 1115-1913 Å, UVIS observed the disk on 13 December, 2004 at low solar activity. The EUV spectrum consists of three band systems of N2 (b 1Πu, b′ 1∑u+, c4′ 1∑u± → X 1∑g+), while the FUV spectrum consists of one (a 1Πg → X 1∑g+). Both the EUV and FUV spectra contain many N I and N II multiplets that are produced primarily by photodissociative ionization. Spectral intensities of the N2 c4′ 1∑u+(v′ = 0) → X 1∑g+(v″ = 0-2) progression from 950-1010 Å are resolved for the first time. The UVIS observations reveal that the c4′ 1∑u+(0) → X 1∑ g+ (0) vibrational band near 958 Å is weak and undetectable, and that N I multiplets near 953.2 and 964.5 Å are present instead. Magnetospheric particle excitation may be weak or sporadic, since the nightside EUV spectrum on this orbit shows no observable nitrogen emission features and only H Ly-β. Copyright 2007 by the American Geophysical Union.

Publication Date

12-28-2007

Publication Title

Geophysical Research Letters

Volume

34

Issue

24

Number of Pages

-

Document Type

Article

Personal Identifier

scopus

DOI Link

https://doi.org/10.1029/2007GL031555

Socpus ID

39549083484 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/39549083484

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