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| Format: | Preprint |
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2025
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| Online Access: | https://arxiv.org/abs/2508.01885 |
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| _version_ | 1866908685791395840 |
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| author | Yildiz, L. Kayki, D. Gudekli, E. |
| author_facet | Yildiz, L. Kayki, D. Gudekli, E. |
| contents | The long-term retention of substantial atmospheres in close-in exoplanets presents a major challenge to classical hydrodynamic escape theory, which predicts rapid mass loss under intense stellar irradiation. In this work, we propose a fully classical, interior-driven suppression mechanism based on thermoelastic contraction of the planetary mantle. By incorporating pressure- and temperature-dependent elastic deformation into the structural evolution of the planet, we demonstrate that radial contraction can lead to measurable increases in surface escape velocity. We analytically derive a modified escape condition and introduce a dimensionless suppression index Xi that quantifies the extent to which internal mechanical response inhibits atmospheric loss. Numerical simulations across a wide parameter space show that volumetric strain values in the range 0.005 to 0.01 can enhance escape velocities by up to 10 percent, leading to a reduction in energy-limited escape rates by over 50 percent. When applied to warm mini-Neptunes such as GJ 1214b, K2-18b, and TOI-270c, the model successfully accounts for their persistent atmospheres without invoking exotic stellar conditions or chemical outliers. Our results indicate that planetary elasticity, often neglected in escape models, plays a first-order role in shaping the atmospheric evolution of close-in worlds. The theory yields specific observational predictions, including suppressed outflow signatures and radius anomalies, which may be testable with JWST, ARIEL, and future spectroscopic missions. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2508_01885 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Thermoelastic Contraction as a Suppressor of Atmospheric Escape in Close-in Exoplanets Yildiz, L. Kayki, D. Gudekli, E. Earth and Planetary Astrophysics The long-term retention of substantial atmospheres in close-in exoplanets presents a major challenge to classical hydrodynamic escape theory, which predicts rapid mass loss under intense stellar irradiation. In this work, we propose a fully classical, interior-driven suppression mechanism based on thermoelastic contraction of the planetary mantle. By incorporating pressure- and temperature-dependent elastic deformation into the structural evolution of the planet, we demonstrate that radial contraction can lead to measurable increases in surface escape velocity. We analytically derive a modified escape condition and introduce a dimensionless suppression index Xi that quantifies the extent to which internal mechanical response inhibits atmospheric loss. Numerical simulations across a wide parameter space show that volumetric strain values in the range 0.005 to 0.01 can enhance escape velocities by up to 10 percent, leading to a reduction in energy-limited escape rates by over 50 percent. When applied to warm mini-Neptunes such as GJ 1214b, K2-18b, and TOI-270c, the model successfully accounts for their persistent atmospheres without invoking exotic stellar conditions or chemical outliers. Our results indicate that planetary elasticity, often neglected in escape models, plays a first-order role in shaping the atmospheric evolution of close-in worlds. The theory yields specific observational predictions, including suppressed outflow signatures and radius anomalies, which may be testable with JWST, ARIEL, and future spectroscopic missions. |
| title | Thermoelastic Contraction as a Suppressor of Atmospheric Escape in Close-in Exoplanets |
| topic | Earth and Planetary Astrophysics |
| url | https://arxiv.org/abs/2508.01885 |