SIMBAD references

2019ApJ...884L..43G - Astrophys. J., 884, L43-L43 (2019/October-3)

Rapid escape of ultra-hot exoplanet atmospheres driven by hydrogen Balmer absorption.

GARCIA MUNOZ A. and SCHNEIDER P.C.

Abstract (from CDS):

Atmospheric escape is key to explaining the long-term evolution of planets in our solar system and beyond, and in the interpretation of atmospheric measurements. Hydrodynamic escape is generally thought to be driven by the flux of extreme-ultraviolet photons that the planet receives from its host star. Here, we show that the escape from planets orbiting hot stars proceeds through a different yet complementary process: drawing its energy from the intense near-ultraviolet emission of the star that is deposited within an optically thin, high-altitude atmospheric layer of hydrogen excited into the lower state of the Balmer series. The ultra-hot exoplanet KELT-9b likely represents the first known instance of this Balmer-driven escape. In this regime of hydrodynamic escape, the near-ultraviolet emission from the star is more important at determining the planet mass loss than the extreme-ultraviolet emission, and uncertainties in the latter become less critical. Further, we predict that gas exoplanets around hot stars may experience catastrophic mass loss when they are less massive than 1-2 Jupiter masses and closer in than KELT-9b, thereby challenging the paradigm that all large exoplanets are stable to atmospheric escape. We argue that extreme escape will affect the demographics of close-in exoplanets orbiting hot stars.

Abstract Copyright: © 2019. The American Astronomical Society. All rights reserved.

Journal keyword(s): Exoplanet atmospheres - Aeronomy - Exoplanet evolution - Radiative transfer

Simbad objects: 4

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2021.01.27-03:30:05

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