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An investigation of Pluto’s troposphere using stellar occultation light curves and an atmospheric radiative-conductive-convective model |
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| Authors: | Angela M. Zalucha Xun Zhu Darrell F. Strobel J.L. Elliot |
| Affiliation: | a Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, MA 02139, USA b Applied Physics Laboratory, The Johns Hopkins University, 11100 Johns Hopkins Road, Laurel, MD 20723, USA c Southern African Large Telescope and South African Astronomical Observatory, P.O. Box 9, Observatory, 7935 Cape Town, South Africa d Department of Earth and Planetary Sciences, The Johns Hopkins University, 3400 N. Charles St., Baltimore, MD 21218, USA e Department of Physics and Astronomy, The Johns Hopkins University, 3400 N. Charles St., Baltimore, MD 21218, USA f Department of Physics, Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, MA 02139, USA g Lowell Observatory, 1400 West Mars Hill Road, Flagstaff, AZ 86001, USA |
| Abstract: | We use a radiative-conductive-convective model to assess the height of Pluto’s troposphere, as well as surface pressure and surface radius, from stellar occultation data from the years 1988, 2002, and 2006. The height of the troposphere, if it exists, is less than 1 km for all years analyzed. Pluto has at most a planetary boundary layer and not a troposphere. As in previous analyses of Pluto occultation light curves, we find that the surface pressure is increasing with time, assuming that latitude and longitude variations in Pluto’s atmosphere are negligible. The surface pressure is found to be slightly higher ( μbar in 1988,  μbar in 2002, and 18.5 ± 4.7 μbar in 2006) than in our previous analyses with the troposphere excluded. The surface radius is determined to be  . Comparison of the minimum reduced chi-squared values between the best-fit radiative-conductive-convective (i.e., troposphere-included) model and best-fit radiative-conductive (i.e., troposphere-excluded) shows that the troposphere-included model is only a slightly better fit to the data for all 3 years. Uncertainties in the small-scale physical processes of Pluto’s lower atmosphere and consequently the functional form of the model troposphere lend more confidence to the troposphere-excluded results. |
| Keywords: | Occultations Pluto, Atmosphere Atmospheres, Structure |
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