Ground-based measurements of the methane distribution on Titan

Paulo F. Penteado, Caitlin Griffith

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

Using spectra taken with NIRSPEC (Near Infrared Spectrometer) and adaptive optics on the Keck II telescope, we resolved the latitudinal variation of the 3 ν2 band of CH3 D at 1.56 μm. As CH3 D is less abundant than CH4 by a factor of 50 ± 10 × 10- 5, these CH3 D lines do not saturate in Titan's atmosphere, and are well characterized by laboratory measurements. Thus they do not suffer from the large uncertainties of the CH4 lines that are weak enough to be unsaturated in Titan. Our measurements of the methane abundance are confined to the latitude range of 32°S-18°N and longitudes sampled by a 0.04″ slit centered at ∼195°W. The methane abundance below 10 km is constant to within 20% in the tropical atmosphere sampled by our observations, consistent with the low surface insolation and lack of surface methane [Griffith, C.A., McKay, C.P., Ferri, F., 2008. Astrophys. J. 687, L41-L44].

Original languageEnglish (US)
Pages (from-to)345-351
Number of pages7
JournalIcarus
Volume206
Issue number1
DOIs
StatePublished - Mar 2010

Fingerprint

Titan
ground-based measurement
methane
Titan atmosphere
D lines
insolation
atmosphere
infrared spectrometers
adaptive optics
slits
near infrared
spectrometer
telescopes
atmospheres
distribution

Keywords

  • Abundances
  • Atmospheres
  • Radiative transfer
  • Satellites
  • Spectroscopy
  • Titan

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

Ground-based measurements of the methane distribution on Titan. / Penteado, Paulo F.; Griffith, Caitlin.

In: Icarus, Vol. 206, No. 1, 03.2010, p. 345-351.

Research output: Contribution to journalArticle

Penteado, Paulo F. ; Griffith, Caitlin. / Ground-based measurements of the methane distribution on Titan. In: Icarus. 2010 ; Vol. 206, No. 1. pp. 345-351.
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AU - Griffith, Caitlin

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AB - Using spectra taken with NIRSPEC (Near Infrared Spectrometer) and adaptive optics on the Keck II telescope, we resolved the latitudinal variation of the 3 ν2 band of CH3 D at 1.56 μm. As CH3 D is less abundant than CH4 by a factor of 50 ± 10 × 10- 5, these CH3 D lines do not saturate in Titan's atmosphere, and are well characterized by laboratory measurements. Thus they do not suffer from the large uncertainties of the CH4 lines that are weak enough to be unsaturated in Titan. Our measurements of the methane abundance are confined to the latitude range of 32°S-18°N and longitudes sampled by a 0.04″ slit centered at ∼195°W. The methane abundance below 10 km is constant to within 20% in the tropical atmosphere sampled by our observations, consistent with the low surface insolation and lack of surface methane [Griffith, C.A., McKay, C.P., Ferri, F., 2008. Astrophys. J. 687, L41-L44].

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