2009/01/30 by E. Lellouch, B. Sicardy, C. de Bérgh +5 · 2 citations
Chemistry · Physics and Astronomy · #Astro and Planetary Science #Astrobiology #Astrophysics and Star Formation Studies #Atmosphere (unit) #Atmospheric methane #Atmospheric sciences #Chemistry #Context (archaeology) #Environmental science #Geology #Meteorology #Methane #Mixing ratio #Physics #Planetary Science and Exploration #Pluto #Surface pressure #Troposphere #astro-ph.EP
paper · pdf · doi:10.1051/0004-6361/200911633
AA vers. 6.1, LaTeX class for Astronomy & Astrophysics, 9 pages with 5 figures Astronomy and Astrophysics Letters, in press
arxiv created 2009/01/30 · openalex publication_date 2009/02/09 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
<i>Context. <i/>Pluto possesses a thin atmosphere, primarily composed of nitrogen, in which the detection of methane has been reported.<i>Aims. <i/>The goal is to constrain essential but so far unknown parameters of Pluto's atmosphere, such as the surface pressure, lower atmosphere thermal stucture, and methane mixing ratio.<i>Methods. <i/>We use high-resolution spectroscopic observations of gaseous methane and a novel analysis of occultation lightcurves.<i>Results. <i/>We show that (i) Pluto's surface pressure is currently in the 6.5–24 <i>μ<i/>bar range, (ii) the methane mixing ratio is 0.5<i>±<i/>0.1%, adequate to explain Pluto's inverted thermal structure and ~100 K upper atmosphere temperature, and (iii) a troposphere is not required by our data, but if present, it has a depth of at most 17 km, i.e. less than one pressure scale height; in this case methane is supersaturated in most of it. The atmospheric and bulk surface abundances of methane are strikingly similar, a possible consequence of a CH<sub>4<sub/>-rich top surface layer.