Role of Planetary Radius on Atmospheric Escape of Rocky Exoplanets

Fuente: arXiv
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Autori principali: Chin, Laura, Dong, Chuanfei, Lingam, Manasvi
Natura: Preprint
Pubblicazione: 2024
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author Chin, Laura
Dong, Chuanfei
Lingam, Manasvi
author_facet Chin, Laura
Dong, Chuanfei
Lingam, Manasvi
contents Large-scale characterization of exoplanetary atmospheres is on the horizon, thereby making it possible in the future to extract their statistical properties. In this context, by using a well validated model in the solar system, we carry out three-dimensional magnetohydrodynamic simulations to compute nonthermal atmospheric ion escape rates of unmagnetized rocky exoplanets as a function of their radius based on fixed stellar radiation and wind conditions. We find that the atmospheric escape rate is, unexpectedly and strikingly, a nonmonotonic function of the planetary radius $R$ and that it evinces a maximum at $R \sim 0.7\,R_\oplus$. This novel nonmonotonic behavior may arise from an intricate tradeoff between the cross-sectional area of a planet (which increases with size, boosting escape rates) and its associated escape velocity (which also increases with size, but diminishes escape rates). Our results could guide forthcoming observations because worlds with certain values of $R$ (such as $R \sim 0.7\,R_\oplus$) might exhibit comparatively higher escape rates when all other factors are constant.
format Preprint
id arxiv_https___arxiv_org_abs_2401_16211
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Role of Planetary Radius on Atmospheric Escape of Rocky Exoplanets
Chin, Laura
Dong, Chuanfei
Lingam, Manasvi
Earth and Planetary Astrophysics
Solar and Stellar Astrophysics
Space Physics
Large-scale characterization of exoplanetary atmospheres is on the horizon, thereby making it possible in the future to extract their statistical properties. In this context, by using a well validated model in the solar system, we carry out three-dimensional magnetohydrodynamic simulations to compute nonthermal atmospheric ion escape rates of unmagnetized rocky exoplanets as a function of their radius based on fixed stellar radiation and wind conditions. We find that the atmospheric escape rate is, unexpectedly and strikingly, a nonmonotonic function of the planetary radius $R$ and that it evinces a maximum at $R \sim 0.7\,R_\oplus$. This novel nonmonotonic behavior may arise from an intricate tradeoff between the cross-sectional area of a planet (which increases with size, boosting escape rates) and its associated escape velocity (which also increases with size, but diminishes escape rates). Our results could guide forthcoming observations because worlds with certain values of $R$ (such as $R \sim 0.7\,R_\oplus$) might exhibit comparatively higher escape rates when all other factors are constant.
title Role of Planetary Radius on Atmospheric Escape of Rocky Exoplanets
topic Earth and Planetary Astrophysics
Solar and Stellar Astrophysics
Space Physics
url https://arxiv.org/abs/2401.16211