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摘要
Recent observations of Ceres, made using the Heterodyne Instrument for the Far Infrared on board the European Space Agency's Herschel Space Observatory, have shown that water vapor is emanated from the low-albedo midlatitude regions. Based on the supposition that some dark spots on Europa may be caused by diapirism, we explored whether Ceres' environment also can induce compositional diapirism, and whether an upwelling diapir could explain the origin and distribution of the dark spots and vaporization of Ceres. If the density of the rock that constitutes Ceres is around 2700 kg m(-3), the undifferentiated crust is stable over geological time periods at less than 180 K. At a surface temperature of 170 K, a diapir can reach the surface if the crust is a few tens of kilometers thick. Alternatively, if the surface temperature is 150 K, a large contrast in viscosity would prevent diapirs from reaching the surface. The relatively moderate surface temperature in the midlatitude regions of Ceres may be the reason for the formation of dark terrains occurring only in such areas. Our finite difference calculations do not show that diapirism melts the surface ice because the temperature gradient changes very little. However, if the observed vapor emission is caused by the sublimation of fresh ice, compositional diapirism could be the mechanism that transports the fresh ice to the surface. In addition to other mechanisms such as cryovolcanism, diapirism is a valid hypothesis for explaining the dark terrain and vapor emissions of Ceres.
- 出版日期2014-12
