Abstract DGP2026-78 |
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Gravitational effects on the ice shell dynamics of the Super-Earth OGLE-2005-BLG-390Lb: Implications for partial melting processes.
OGLE-2005-BLG-390Lb is one of the coldest exoplanets known, with estimated surface temperatures between 35 K and 47 K. Despite its icy exterior and the distance from its host star, internal heating may still support localized subsurface partial melting under specific gravitational conditions and chemical composition. In this study, we aim to investigate the early thermal evolution and internal dynamics of this Super-Earth, with a focus on melt generation within the ice shell under varying surface temperature and gravitational acceleration. We perform two-dimensional numerical simulations incorporating temperature-dependent viscosity and a chemical composition of H2O–NH3 mixture. The models explore a range of surface temperatures (47 K and 80 K) and gravitational accelerations (5 m/s², 10 m/s², and 18 m/s²) to assess their influence on convective vigor and potential partial melting generation. Our results show that lower gravitational accelerations promote thicker stagnant lids and more vigorous convection, enabling basal temperatures to reach or exceed the ammonia–water ice eutectic melting point, independent of the surface temperature. This leads to localized and sustained partial melting, even in the absence of tidal or radiogenic heatings. These outcomes might offer additional perspectives on the possible internal dynamics and habitability of icy exoplanets orbiting low luminosity stars.