Solar occultation by titan measured by cassini/UVIS

Fernando J. Capalbo, Yves Bénilan, Roger V. Yelle, Tommi T. Koskinen, Bill R. Sandel, Gregory M. Holsclaw, William E. McClintock

Research output: Contribution to journalArticle

7 Scopus citations

Abstract

We present the first published analysis of a solar occultation by Titan's atmosphere measured by the Ultraviolet Imaging Spectrograph on board Cassini. The data were measured during flyby T53 in 2009 April and correspond to latitudes between 21° and 28° south. The analysis utilizes the absorption of two solar emission lines (584 Å and 630 Å) in the ionization continuum of the N2 absorption cross section and solar emission lines around 1085 Å where absorption is due to CH4. The measured transmission at these wavelengths provides a direct estimate of the N2 and CH4 column densities along the line of sight from the spacecraft to the Sun, which we inverted to obtain the number densities. The high signal-to-noise ratio of the data allowed us to retrieve density profiles in the altitude range 1120-1400 km for nitrogen and 850-1300 km for methane. We find an N2 scale height of 76 km and a temperature of 153 K. Our results are in general agreement with those from previous work, although there are some differences. Particularly, our profiles agree, considering uncertainties, with the density profiles derived from the Voyager 1 Ultraviolet Spectrograph data, and with in situ measurements by the Ion Neutral Mass Spectrometer with revised calibration.

Original languageEnglish (US)
Article numberL16
JournalAstrophysical Journal Letters
Volume766
Issue number2
DOIs
StatePublished - Apr 1 2013

Keywords

  • Sun: UV radiation
  • instrumentation: spectrographs
  • occultations
  • planets and satellites: atmospheres
  • planets and satellites: individual (Titan)
  • space vehicles: instruments

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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    Capalbo, F. J., Bénilan, Y., Yelle, R. V., Koskinen, T. T., Sandel, B. R., Holsclaw, G. M., & McClintock, W. E. (2013). Solar occultation by titan measured by cassini/UVIS. Astrophysical Journal Letters, 766(2), [L16]. https://doi.org/10.1088/2041-8205/766/2/L16