Estimating photoevaporative mass loss of exoplanets with <scp>PLATYPOS</scp>

Ketzer, Laura; Poppenhaeger, Katja

doi:10.1002/asna.20210105

Cited by 4 publications

(2 citation statements)

References 47 publications

(81 reference statements)

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“…We consider here the atmospheric mass-loss driven by stellar XUV photons, and investigate how the inclusion of a distribution of low, medium and high activity tracks for the host star -as opposed to assuming only one track for all stars in the population -affects the final planetary radius distribution at mature system ages. Our calculations are performed with the publicly available python code PLATYPOS 1 , for which a description of the code's fuctionality was presented in Ketzer & Poppenhaeger (2022). In the following, we describe the relevant inputs for this work in more detail.…”

Section: Planetary Mass Lossmentioning

confidence: 99%

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The influence of host star activity evolution on the population of super-Earths and mini-Neptunes

Ketzer¹,

Poppenhaeger²

2022

Preprint

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The detected exoplanet population displays a dearth of planets with sizes of about two Earth radii, the so-called radius gap. This is interpreted as an evolutionary effect driven by a variety of possible atmospheric mass loss processes of exoplanets. For mass loss driven by an exoplanet's irradiation by stellar X-ray and extreme-UV photons, the time evolution of the stellar magnetic activity is important. It is known from observations of open stellar clusters that stars of the same age and mass do not all follow the same time evolution of activity-induced X-ray and extreme-UV luminosities. Here we explore how a realistic spread of different stellar activity tracks influences the mass loss and radius evolution of a simulated population of small exoplanets and the observable properties of the radius gap. Our results show qualitatively that different saturation time scales, i.e. the young age at which stellar high-energy emission starts to decline, and different activity decay tracks over moderate stellar ages can cause changes in the population density of planets in the gap, as well as in the observable width of the gap. We also find that while the first 100 million years of mass loss are highly important to shape the radius gap, significant evolution of the gap properties is expected to take place for at least the first 500-600 million years, i.e. the age of the Hyades cluster. Observations of exoplanet populations with defined ages will be able to shed more light on the radius gap evolution.

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Section: Planetary Mass Lossmentioning

confidence: 99%

“…This work is based on simulations with the publicly available code "Planetary Photoevaporation Simulator (PLATYPOS)" (Ketzer & Poppenhaeger 2022), which can be accessed on Github (https://github.com/lketzer/platypos/).…”

Section: Data Availabilitymentioning

confidence: 99%

The influence of host star activity evolution on the population of super-Earths and mini-Neptunes

Ketzer¹,

Poppenhaeger²

2022

Preprint

Self Cite

View full text Add to dashboard Cite

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The influence of host star activity evolution on the population of super-Earths and mini-Neptunes

Ketzer

Poppenhaeger

2022

Monthly Notices of the Royal Astronomical Society

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The detected exoplanet population displays a dearth of planets with sizes of about two Earth radii, the so-called radius gap. This is interpreted as an evolutionary effect driven by a variety of possible atmospheric mass loss processes of exoplanets. For mass loss driven by an exoplanet’s irradiation by stellar X-ray and extreme-UV photons, the time evolution of the stellar magnetic activity is important. It is known from observations of open stellar clusters that stars of the same age and mass do not all follow the same time evolution of activity-induced X-ray and extreme-UV luminosities. Here we explore how a realistic spread of different stellar activity tracks influences the mass loss and radius evolution of a simulated population of small exoplanets and the observable properties of the radius gap. Our results show qualitatively that different saturation time scales, i.e. the young age at which stellar high-energy emission starts to decline, and different activity decay tracks over moderate stellar ages can cause changes in the population density of planets in the gap, as well as in the observable width of the gap. We also find that while the first 100 million years of mass loss are highly important to shape the radius gap, significant evolution of the gap properties is expected to take place for at least the first 500-600 million years, i.e. the age of the Hyades cluster. Observations of exoplanet populations with defined ages will be able to shed more light on the radius gap evolution.

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Three young planets around the K-dwarf K2-198: high-energy environment, evaporation history, and expected future

Ketzer,

Poppenhaeger,

Baratella

et al. 2023

Monthly Notices of the Royal Astronomical Society

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Planets orbiting young stars are thought to experience atmospheric evaporation as a result of the host stars’ high magnetic activity. We study the evaporation history and expected future of the three known transiting exoplanets in the young multiplanet system K2-198. Based on spectroscopic and photometric measurements, we estimate an age of the K-dwarf host star between 200 and 500 Myr, and calculate the high-energy environment of these planets using eROSITA X-ray measurements. We find that the innermost planet K2-198c has likely lost its primordial envelope within the first few tens of Myr regardless of the age at which the star drops out of the saturated X-ray regime. For the two outer planets, a range of initial envelope mass fractions is possible, depending on the not-yet-measured planetary mass and the stars’ spin-down history. Regarding the future of the system, we find that the outermost planet K2-198b is stable against photoevaporation for a wide range of planetary masses, while the middle planet K2-198d is only able to retain an atmosphere for a mass range between ∼7 and 18 M⊕. Lower-mass planets are too susceptible to mass loss, and a very thin present-day envelope for higher-mass planets is easily lost with the estimated mass-loss rates. Our results support the idea that all three planets started out above the radius valley in the (sub-)Neptune regime and were then transformed into their current states by atmospheric evaporation, but also stress the importance of measuring planetary masses for (young) multiplanet systems before conducting more detailed photoevaporation simulations.

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Estimating photoevaporative mass loss of exoplanets with PLATYPOS

Cited by 4 publications

References 47 publications

The influence of host star activity evolution on the population of super-Earths and mini-Neptunes

The influence of host star activity evolution on the population of super-Earths and mini-Neptunes

The influence of host star activity evolution on the population of super-Earths and mini-Neptunes

Three young planets around the K-dwarf K2-198: high-energy environment, evaporation history, and expected future

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