Habitable Evaporated Cores: Transforming Mini-Neptunes into Super-Earths in the Habitable Zones of M Dwarfs

Abstract

We show that photoevaporation of small gaseous exoplanets ("mini-Neptunes") in the habitable zones of M dwarfs can remove several Earth masses of hydrogen and helium from these planets and transform them into potentially habitable worlds. We couple X-ray/extreme ultraviolet (XUV)-driven escape, thermal evolution, tidal evolution and orbital migration to explore the types of systems that may harbor such "habitable evaporated cores" (HECs). We find that HECs are most likely to form from planets with $\sim 1M_{\oplus }$ solid cores with up to about 50% H/He by mass, though whether or not a given mini-Neptune forms a HEC is highly dependent on the early XUV evolution of the host star. As terrestrial planet formation around M dwarfs by accumulation of local material is likely to form planets that are small and dry, evaporation of small migrating mini-Neptunes could be one of the dominant formation mechanisms for volatile-rich Earths around these stars.

Published in Astrobiology 15:1. Published version available for free at http://online.liebertpub.com/toc/ast/15/1

References in corpus (20)

• The K2 Mission: Characterization and Early results
• 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
• Origins of Eccentric Extrasolar Planets: Testing the Planet-Planet Scattering Model
• Roche lobe effects on the atmospheric loss of "Hot Jupiters"
• Toward a Deterministic Model of Planetary Formation V. Accumulation Near the Ice Line
• Tidal Evolution of Close-in Extra-Solar Planets
• Migration and the formation of systems of hot super-Earths and Neptunes
• An Earth-sized Planet in the Habitable Zone of a Cool Star
• Tidal friction in close-in satellites and exoplanets. The Darwin theory re-visited
• Kepler-62: A five-planet system with planets of 1.4 and 1.6 Earth radii in the Habitable Zone
• Lyman-$\alpha$ Transit Spectroscopy and the Neutral Hydrogen Tail of the Hot Neptune GJ436b
• A decreased probability of habitable planet formation around low-mass stars
• Resonant Repulsion of Kepler Planet Pairs
• Bayesian search for low-mass planets around nearby M dwarfs. Estimates for occurrence rate based on global detectability statistics
• Probing the Blow-Off Criteria of Hydrogen-Rich "Super-Earths"
• Could we identify hot Ocean-Planets with CoRoT, Kepler and Doppler velocimetry?
• Interacting Binaries with Eccentric Orbits II. Secular Orbital Evolution Due To Non-Conservative Mass Transfer
• Accretion and Evolution of ~2.5 Earth-mass Planets with Voluminous H/He Envelopes

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• Extreme Water Loss and Abiotic O${}_2$ Buildup On Planets Throughout the Habitable Zones of M Dwarfs
• The Kepler Catalog of Stellar Flares
• The active lives of stars: a complete description of rotation and XUV evolution of F, G, K, and M dwarfs
• The Detectability and Characterization of the TRAPPIST-1 Exoplanet Atmospheres with JWST
• Predictions of the atmospheric composition of GJ 1132b
• A path towards understanding the rotation-activity relation of M dwarfs with K2 mission, X-ray and UV data
• MOST Observations of our Nearest Neighbor: Flares on Proxima Centauri
• Double Trouble: Two Transits of the Super-Earth GJ 1132 b Observed with JWST NIRSpec G395H
• The Evolution of Flare Activity with Stellar Age
• Atmospheres of Rocky Exoplanets
• Constraining planet structure and composition from stellar chemistry: trends in different stellar populations
• JWST/NIRISS reveals the water-rich "steam world" atmosphere of GJ 9827 d
• The Exoplanet Radius Valley from Gas-driven Planet Migration and Breaking of Resonant Chains
• Extreme hydrodynamic losses of Earth-like atmospheres in the habitable zones of very active stars
• Hydrogen dominated atmospheres on terrestrial mass planets: evidence, origin and evolution
• The Role of N2 as a Geo-Biosignature for the Detection and Characterization of Earth-like Habitats
• TRAPPIST-1: Global Results of the Spitzer Exploration Science Program {\it Red Worlds}
• Evidence for the volatile-rich composition of a 1.5-$R_{\oplus }$ planet
• Current Population Statistics Do Not Favor Photoevaporation over Core-Powered Mass Loss as the Dominant Cause of the Exoplanet Radius Gap
• Magma ocean evolution of the TRAPPIST-1 planets
• The erosion of large primary atmospheres typically leaves behind substantial secondary atmospheres on temperate rocky planets
• The Pale Green Dot: A Method to Characterize Proxima Centauri b using Exo-Aurorae
• Observing Isotopologue Bands in Terrestrial Exoplanet Atmospheres with the James Webb Space Telescope---Implications for Identifying Past Atmospheric and Ocean Loss
• Escaping Helium and a Highly Muted Spectrum Suggest a Metal-Enriched Atmosphere on Sub-Neptune GJ3090b from JWST Transit Spectroscopy
• HAZMAT II: Ultraviolet Variability of Low-Mass Stars in the GALEX Archive
• Less effective hydrodynamic escape of H${}_2$-H${}_2$O atmospheres on terrestrial planets orbiting pre-main sequence M dwarfs
• Habitability and Water Loss Limits on Eccentric Planets Orbiting Main Sequence Stars
• HAZMAT. VII. The Evolution of Ultraviolet Emission with Age and Rotation for Early M Dwarf Stars
• A multi-wavelength look at the GJ 9827 system -- No evidence of extended atmospheres in GJ 9827 b and d from HST and CARMENES data
• A Coupled Analysis of Atmospheric Mass Loss and Tidal Evolution in XUV Irradiated Exoplanets: the TRAPPIST-1 Case Study
• Stellar Flares versus Luminosity: XUV-induced Atmospheric Escape and Planetary Habitability
• The Thermal Emission Spectrum of the Nearby Rocky Exoplanet LTT 1445A b from JWST MIRI/LRS
• Potential long-term habitable conditions on planets with primordial H-He atmospheres
• Transit Ly-$\alpha$ signatures of terrestrial planets in the habitable zones of M dwarfs
• The space weather around the exoplanet GJ 436b
• Evaluating the Evidence for Water World Populations using Mixture Models
• High resolution near-infrared spectroscopy of a flare around the ultracool dwarf vB 10
• High-energy spectra of LTT 1445A and GJ 486 reveal flares and activity
• Comparative analysis of the influence of Sgr A* and nearby active galactic nuclei on the mass loss of known exoplanets
• Host Star Dependence of Small Planet Mass-Radius Distributions
• High-Resolution Spectral Discriminants of Ocean Loss for M Dwarf Terrestrial Exoplanets
• The Solar Neighborhood L: Spectroscopic Discovery of K Dwarfs Younger Than 1 Gyr and New Binaries within 30 pc
• Hot Rocks Survey V: Secondary Eclipse Photometry of GJ 3473 b with JWST/MIRI
• MAUVE: An Ultraviolet Astrophysics Probe Mission Concept
• How black hole activity may influence exoplanetary evolution in our Galaxy
• Comparative Analysis of the Model for Exoplanet Atmosphere Outflow
• Why M-dwarf flares have limited impact on the atmospheric evaporation of sub-Neptunes and Earth-sized planets
• Simulated Effects of Radioactive Elements on Magnetic Evolution and Atmospheric Mass Loss of Earth-like Planets
• Biosignature false positives in potentially habitable planets around M dwarfs: the effect of UV radiation from one flare
• Chemistry, Climate, and Transmission Spectra of TRAPPIST-1 e Explored with a Multimodel Sparse Sampled Ensemble
• A Multi-Planet System's Sole Super-Puff: Exploring Allowable Physical Parameters for the Cold Super-Puff HIP 41378 f