| | 3 | |
| | 4 | = Murray-Clay paper = |
| | 5 | Authors seek to numerically determine validity of hypothesis that hot Jupiters could be evaporated down to their rocky cores over the planetary lifetime. They use a one-dimensional model that includes heating/cooling terms, tidal gravity, and the effects of ionization on the mass-loss rate, and focus on the substellar point, at which tidal gravity and UV flux are greatest, thereby putting an upper limit on the possible mass-loss rate of the planet (by extending the one-dimensional result over the surface of the planet). They assume a planet of 1.4 R,,J,, and 0.7 M,,J,, and ignore the Coriolis force, under the assumption that the Lyman-alpha radiation from excited H is the only significant cooling term. Numerically, they use a relaxation solver, and find solutions iteratively by removing simplifying conditions one at a time. |
| | 6 | |
| | 7 | They find that, for main-sequence stars, about 20% of H is still neutral at the sonic point, and place an upper bound of ~3.3*10^10^ g/s on the mass loss rate. For hotter (T Tauri) stars, they find an upper bound of ~6.4*10^12^ g/s. At low flux, the mass loss is energy-limited, while for higher flux, the mass loss is radiation/recombination-limited. The assumption of a hydrodynamic wind is shown to be self-consistent, and they estimate that, due to the directionality of the tidal gravity and the UV irradiation, the maximum rate is an overestimate by ~4x. By reducing the wind speed to subsonic values and including a stellar wind, the day-side wind may be reduced or completely suppressed - they hypothesize that this may lead to night-side outflows, due to circulation of hot gases from the day-side. |
| | 8 | |
| | 9 | They compare observations to estimates from their model, and note that the disagreement in Lyman-alpha lines could be due to a variety of factors, including some missing physics or a cause unrelated to absorption by the planetary wind. A promising candidate is cited as acceleration of neutral hydrogen due to charge exchange. They note that modelled spectrally-unresolved measurements appear to be in agreement with observation. |
