Hydrodynamic escape of water vapor atmospheres near very active stars

Abstract

When exposed to the high energy X-ray and ultraviolet radiation of a very active star, water vapor in the upper atmospheres of planets can be photodissociated and rapidly lost to space. In this paper, I study the chemical, thermal, and hydrodynamic processes in the upper atmospheres of terrestrial planets, concentrating on water vapor dominated atmospheres orbiting in the habitable zones of active stars. I consider different stellar activity levels and find very high levels of atmospheric escape in all cases, with the outflowing gas being dominated by atomic hydrogen and oxygen in both their neutral and ion forms. In the lower activity cases, I find that the accumulation of O${}_2$ and increases in the D/H ratios in the atmospheres due to mass fractionation are possible, but in the higher activity cases no mass fractionation takes place. Connecting these results to stellar activity evolution tracks for solar mass stars, I show that huge amounts of water vapor can be lost, and both the losses and the amount of O${}_2$ that can be accumulated in the atmosphere depend sensitively on the star's initial rotation rate. For an Earth-mass planet in the habitable zone of a low-mass M-dwarf, my results suggest that the accumulation of atmospheric O${}_2$ is unlikely unless water loss can take place after the star's most active phase.

12 pages, 9 figures, 1 table, accepted for publication in ApJ

References in corpus (21)

• Atmospheric Escape from Hot Jupiters
• Constraining the Age-Activity Relation for Cool Stars: The SDSS DR5 Low-Mass Star Spectroscopic Sample
• Extreme Water Loss and Abiotic O${}_2$ Buildup On Planets Throughout the Habitable Zones of M Dwarfs
• Water vapour in the atmosphere of the habitable-zone eight Earth-mass planet K2-18 b
• The Extreme Ultraviolet and X-Ray Sun in Time: High-Energy Evolutionary Tracks of a Solar-Like Star
• Stellar Winds on the Main-Sequence II: the Evolution of Rotation and Winds
• Abiotic oxygen-dominated atmospheres on terrestrial habitable zone planets
• Generalized investigation of the rotation-activity relation: Favouring rotation period instead of Rossby number
• Carbon monoxide and water vapor in the atmosphere of the non-transiting exoplanet HD 179949 b
• Predictions of the atmospheric composition of GJ 1132b
• Magnetic moment and plasma environment of HD 209458b as determined from Ly$\alpha$ observations
• The Habitable Zones of Pre-Main-Sequence Stars
• New observations of the extended hydrogen exosphere of the extrasolar planet HD209458b
• The long egress of GJ~436b's giant exosphere
• Magnetospheric Structure and Atmospheric Joule Heating of Habitable Planets Orbiting M-dwarf Stars
• Atmosphere Expansion and Mass Loss of Close-Orbit Giant Exoplanets heated by Stellar XUV. II. Effects of Planetary Magnetic Field, Structuring of inner Magnetosphere
• Extreme hydrodynamic losses of Earth-like atmospheres in the habitable zones of very active stars
• Hydrodynamic simulations of captured protoatmospheres around Earth-like planets
• Solar XUV and ENA-driven water loss from early Venus' steam atmosphere
• A chemical kinetics code for modelling exoplanetary atmospheres
• Transit Ly-$\alpha$ signatures of terrestrial planets in the habitable zones of M dwarfs

Cited by in corpus (38)

• The active lives of stars: a complete description of rotation and XUV evolution of F, G, K, and M dwarfs
• Exoplanet secondary atmosphere loss and revival
• Water on Hot Rocky Exoplanets
• A review of possible planetary atmospheres in the TRAPPIST-1 system
• The long-term evolution of the atmosphere of Venus: processes and feedback mechanisms
• Detection of Ongoing Mass Loss from HD 63433c, a Young Mini Neptune
• Survival of Terrestrial N2-O2 Atmospheres in Violent XUV Environments through Efficient Atomic Line Radiative Cooling
• GJ 273: On the formation, dynamical evolution and habitability of a planetary system hosted by an M dwarf at 3.75 parsec
• Lava Worlds: From Early Earth to Exoplanets
• The young Sun's XUV-activity as a constraint for lower CO${}_2$-limits in the Earth's Archean atmosphere
• Distinguishing between wet and dry atmospheres of TRAPPIST-1 e and f
• Airy worlds or barren rocks? On the survivability of secondary atmospheres around the TRAPPIST-1 planets
• Less effective hydrodynamic escape of H${}_2$-H${}_2$O atmospheres on terrestrial planets orbiting pre-main sequence M dwarfs
• The influence of the environment on the spin evolution of low-mass stars. I. External photoevaporation of circumstellar disks
• One Year in the Life of Young Suns: Data Constrained Corona-Wind Model of kappa1 Ceti
• Evolution of X-ray Activity in <25 Myr Old Pre-Main Sequence Stars
• A transmission spectrum of the sub-Earth planet L98-59~b in 1.1-1.7 $\mu$m
• Bioverse: The Habitable Zone Inner Edge Discontinuity as an Imprint of Runaway Greenhouse Climates on Exoplanet Demographics
• Hubble WFC3 Spectroscopy of the Terrestrial Planets L~98-59~c \& d: No Evidence for a Clear Hydrogen Dominated Primary Atmosphere
• Resonant sub-Neptunes are puffier
• The homogeneous characterisation of Ariel host stars
• Heating and ionization by non-thermal electrons in the upper atmospheres of water-rich exoplanets
• Evolution of the Earth's Polar Outflow From Mid-Archean to Present
• The three regimes of atmospheric evaporation for super-Earths and sub-Neptunes
• Eta-Earth Revisited II: Deriving a Maximum Number of Earth-like Habitats in the Galactic Disk
• The Cosmic Shoreline Revisited: A Metric for Atmospheric Retention Informed by Hydrodynamic Escape
• Habitable Zone and Atmosphere Retention Distance (HaZARD) Stellar-evolution-dependent loss models of secondary atmospheres
• An Earth-sized Planet around an M5 Dwarf Star at 22 pc
• Implications of Abiotic Oxygen Buildup for Earth-like Complex Life
• Volatile-rich evolution of molten super-Earth L 98-59 d
• Searching for Hot Water World Candidates with CHEOPS: Refining the radii and analysing the internal structures and atmospheric lifetimes of TOI-238 b and TOI-1685 b
• Novel Physics of Escaping Secondary Atmospheres May Shape the Cosmic Shoreline
• The New Generation Planetary Population Synthesis (NGPPS) VIII. Impact of host star metallicity on planet occurrence rates, orbital periods, eccentricities, and radius valley morphology
• Modeling Atmospheric Ion Escape from Kepler-1649 b and c over Time
• Evolution and Observable Properties of Rocky Planet Atmospheres
• Main ways in which stars influence the climate and surface habitability of their planets
• Hidden water in magma ocean exoplanets
• ExoplANETS-A: A VO database for host stars and planetary systems: The effect of XUV on planet atmospheres