Methane absorption variations in the spectrum of Pluto

M. W. Buie and U. Fink. Icarus 70, 483-498 (1987).


The lightcurve phases of 0.18, 0.35, 0.49, and 0.98 covered by 5600-10,500 Angstrom absolute spectrophotometry of Pluto during four nights include minimum (0.98) light and one near-maximum (0.49) light. The spectra are noted to exhibit significant methane band absorption depth variations at 6200, 7200, 7900, 8400, 8600, 8900, and 10,000 Angstroms, with the minimum absorption occurring at minimum light and thereby indicating a 30-percent change in the methane column abundance in the course of three days. An attempt is made to model this absorption strength variation with rotational phase terms of an isotropic surface distribution of methane frost and a clear layer of CH4 gas.

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