Assessing Core-Powered Mass Loss in the Context of Early Boil-Off: Minimal Long-Lived Mass Loss for the Sub-Neptune Population
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| Format: | Preprint |
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2024
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| _version_ | 1866912069040734208 |
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| author | Tang, Yao Fortney, Jonathan J. Murray-Clay, Ruth |
| author_facet | Tang, Yao Fortney, Jonathan J. Murray-Clay, Ruth |
| contents | We develop a python-based state-of-the-art sub-Neptune evolution model that incorporates both the post-formation boil-off at young ages $\leq$ 1 Myr and long-lived core-powered mass loss ($\sim$ Gyrs) from interior cooling. We investigate the roles of initial H/He entropy, core luminosity, energy advection, radiative atmospheric structure, and the transition to an XUV-driven mass-loss phase, with an eye on relevant timescales for planetary mass loss and thermal evolution. With particular attention to the re-equilibration process of the H/He envelope, including the energy sources that fuel the hydrodynamic wind, and energy transport timescales, we find boil-off and core-powered escape are primarily driven by stellar bolometric radiation. We further find that both boil-off and core-powered escape are decoupled from the thermal evolution. We show that, with a boil-off phase that accounts for the initial H/He mass fraction and initial entropy, post-boil-off core-powered escape has an insignificant influence on the demographics of small planets, as it is only able to remove at most 0.1% of the H/He mass fraction. Our numerical results are directly compared to previous work on analytical core-powered mass loss modeling for individual evolutionary trajectories and populations of small planets. We examine a number of assumptions made in previous studies that cause significant differences compared to our findings. We find that boil-off, though able to completely strip the gaseous envelope from a highly irradiated ($F \geq 100 F_\oplus$) planet that has a low-mass core ($M_c \leq 4M_\oplus$), cannot by itself form a pronounced radius gap as is seen in the observed population. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2410_08577 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Assessing Core-Powered Mass Loss in the Context of Early Boil-Off: Minimal Long-Lived Mass Loss for the Sub-Neptune Population Tang, Yao Fortney, Jonathan J. Murray-Clay, Ruth Earth and Planetary Astrophysics We develop a python-based state-of-the-art sub-Neptune evolution model that incorporates both the post-formation boil-off at young ages $\leq$ 1 Myr and long-lived core-powered mass loss ($\sim$ Gyrs) from interior cooling. We investigate the roles of initial H/He entropy, core luminosity, energy advection, radiative atmospheric structure, and the transition to an XUV-driven mass-loss phase, with an eye on relevant timescales for planetary mass loss and thermal evolution. With particular attention to the re-equilibration process of the H/He envelope, including the energy sources that fuel the hydrodynamic wind, and energy transport timescales, we find boil-off and core-powered escape are primarily driven by stellar bolometric radiation. We further find that both boil-off and core-powered escape are decoupled from the thermal evolution. We show that, with a boil-off phase that accounts for the initial H/He mass fraction and initial entropy, post-boil-off core-powered escape has an insignificant influence on the demographics of small planets, as it is only able to remove at most 0.1% of the H/He mass fraction. Our numerical results are directly compared to previous work on analytical core-powered mass loss modeling for individual evolutionary trajectories and populations of small planets. We examine a number of assumptions made in previous studies that cause significant differences compared to our findings. We find that boil-off, though able to completely strip the gaseous envelope from a highly irradiated ($F \geq 100 F_\oplus$) planet that has a low-mass core ($M_c \leq 4M_\oplus$), cannot by itself form a pronounced radius gap as is seen in the observed population. |
| title | Assessing Core-Powered Mass Loss in the Context of Early Boil-Off: Minimal Long-Lived Mass Loss for the Sub-Neptune Population |
| topic | Earth and Planetary Astrophysics |
| url | https://arxiv.org/abs/2410.08577 |