Séminaire "Sublimation-driven convection in Sputnik Planitia, Pluto" par Gaël Choblet

Jeudi 07 Octobre 2021, 13:00 - 14:00
par Stéphanie BEAUNAY


Résumé : Sputnik Planitia is a nitrogen ice filled basin on Pluto. Its polygonal surface patterns have been previously explained as a result of solid state convection with either an imposed heat flow or a temperature difference within the 10 km thick ice layer. Neither explanation is satisfactory, because they do not exhibit surface topography with the observed pattern: flat polygons delimited by narrow troughs. Internal heating produces the observed patterns, but the heating source in such a setup remains enigmatic. Here we report the results of modeling the effects of sublimation at the surface. We find that sublimation driven convection readily produces the observed polygonal structures if we assume a smaller heat flux (∼ 0.3 mW m−2) at the base of the ice layer than the commonly accepted value of 2 − 3 mW m−2. Sustaining this regime with the latter value is also possible, but would require a stronger viscosity contrast (∼ 3000) than the nominal value (∼ 100) considered in this study.