Article Dans Une Revue Astronomy & Astrophysics - A&A Année : 2011

High resolution spectroscopy of Pluto's atmosphere: detection of the 2.3 mum CH4 bands and evidence for carbon monoxide

Résumé


Aims: The goal is to determine the composition of Pluto's atmosphere and to constrain the nature of surface-atmosphere interactions.
Methods: We perform high-resolution spectroscopic observations in the 2.33-2.36 mum range, using CRIRES at the VLT.
Results: We obtain (i) the first detection of gaseous methane in this spectral range, through lines of the nu3 + nu4 and nu1 + nu4 bands (ii) strong evidence (6-sigma confidence) for gaseous CO in Pluto. For an isothermal atmosphere at 90 K, the CH4 and CO column densities are 0.75 and 0.07 cm-am, within factors of 2 and 3, respectively. Using a physically-based thermal structure model of Pluto's atmosphere also satisfying constraints from stellar occultations, we infer CH4 and CO mixing ratios qCH_4= 0.6+0.6_{-0.3}% (consistent with results from the 1.66 mum range) and qCO = 0.5+1_{-0.25 × 10-3}. The CO atmospheric abundance is consistent with its surface abundance. As for Triton, it is probably controlled by a thin, CO-rich, detailed balancing layer resulting from seasonal transport and/or atmospheric escape.

Dates et versions

hal-03785249 , version 1 (23-09-2022)

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Emmanuel Lellouch, Catherine de Bergh, Bruno Sicardy, Hans-Ulrich Käufl, A. Smette. High resolution spectroscopy of Pluto's atmosphere: detection of the 2.3 mum CH4 bands and evidence for carbon monoxide. Astronomy & Astrophysics - A&A, 2011, 530, pp.L4. ⟨10.1051/0004-6361/201116954⟩. ⟨hal-03785249⟩
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