A Volatile-Poor Formation of LHS 3844b based on its Lack of Significant Atmosphere

Abstract

Exoplanet discoveries have reached into the realm of terrestrial planets that are becoming the subject of atmospheric studies. One such discovery is LHS 3844b, a 1.3 Earth radius planet in a 0.46 day orbit around an M4.5-5 dwarf star. Follow-up observations indicate that the planet is largely devoid of substantial atmosphere. This lack of significant atmosphere places astrophysical and geophysical constraints on LHS 3844b, primarily the degree of volatile outgassing and the rate of atmosphere erosion. We estimate the age of the host star as $7.8\pm 1.6$ Gyrs and find evidence of an active past comparable to Proxima Centauri. We use geodynamical models of volcanic outgassing and atmospheric erosion to show that the apparent lack of atmosphere is consistent with a volatile-poor mantle for LHS 3844b. We show the core is unlikely to host enough C to produce a sufficiently volatile-poor mantle, unless the bulk planet is volatile-poor relative to Earth. While we cannot rule out a giant impact stripping LHS 3844b's atmosphere, we show this mechanism would require significant mantle stripping, potentially leaving LHS 3844b as an Fe-rich "super-Mercury". Atmospheric erosion by smaller impacts is possible, but only if the planet has already begun degassing and is bombarded by $10^3$ impactors of radius 500-1000 km traveling at escape velocity. We discuss formation and migration scenarios that could account for a volatile poor origin, including the potential for an unobserved massive companion planet. A relatively volatile-poor composition of LHS 3844b suggests that the planet formed interior to the system snow-line.

arXiv comment23 pages, 14 figures, accepted for publication in the Planetary Science Journal

References in corpus (61)

• The Transiting Exoplanet Survey Satellite
• Spectral Energy Distributions of T Tauri Stars With Passive Circumstellar Disks
• Seven temperate terrestrial planets around the nearby ultracool dwarf star TRAPPIST-1
• The NASA Exoplanet Archive: Data and Tools for Exoplanet Research
• The stellar activity-rotation relationship and the evolution of stellar dynamos
• Ages for illustrative field stars using gyrochronology: viability, limitations and errors
• Evolutionary models for low-mass stars and brown dwarfs: uncertainties and limits at very young ages
• Probabilistic Forecasting of the Masses and Radii of Other Worlds
• A Framework for Prioritizing the TESS Planetary Candidates Most Amenable to Atmospheric Characterization
• The Transiting Exoplanet Survey Satellite: Simulations of planet detections and astrophysical false positives
• Mass-Radius Relation for Rocky Planets based on PREM
• A Catalog of Northern Stars With Annual Proper Motions Larger Than 0.15 Seconds of Arc (LSPM catalog - North)
• The H$\alpha$ emission of nearby M dwarfs and its relation to stellar rotation
• The nature of the TRAPPIST-1 exoplanets
• Large-scale magnetic topologies of early M dwarfs
• A map of the large day-night temperature gradient of a super-Earth exoplanet
• A Revised Exoplanet Yield from the Transiting Exoplanet Survey Satellite (TESS)
• Atmospheric Escape and the Evolution of Close-in Exoplanets
• Stellar Abundances in the Solar Neighborhood: The Hypatia Catalog
• The stellar rotation--activity relationship in fully convective M dwarfs
• The rotation and Galactic kinematics of mid M dwarfs in the Solar Neighborhood
• Toroidal versus poloidal magnetic fields in Sun-like stars: a rotation threshold
• Chromospheric Activity, Rotation, and Rotational Braking in M and L Dwarfs
• Absence of a thick atmosphere on the terrestrial exoplanet LHS 3844b
• Fossilized condensation lines in the Solar System protoplanetary disk
• Atmospheric Mass Loss During Planet Formation: The Importance of Planetesimal Impacts
• Atmospheric escape from the TRAPPIST-1 planets and implications for habitability
• Solar-type dynamo behaviour in fully convective stars without a tachocline
• Evolution of Snow Line in Optically Thick Protoplanetary Disks: Effects of Water Ice Opacity and Dust Grain Size
• TESS Discovery of an ultra-short-period planet around the nearby M dwarf LHS 3844
• Is Proxima Centauri b habitable? -- A study of atmospheric loss
• A Catalog of Kepler Habitable Zone Exoplanet Candidates
• Scaling the Earth: A Sensitivity Analysis of Terrestrial Exoplanetary Interior Models
• Formation of Early Water Oceans on Rocky Planets
• The 55 Cnc system reassessed
• Towards precise stellar ages: combining isochrone fitting with empirical gyrochronology
• Tidal heating of Earth-like exoplanets around M stars: Thermal, magnetic, and orbital evolutions
• The Frequency of Giant impacts on Earth-like Worlds
• Outgassing on stagnant-lid super-Earths
• A giant impact as the likely origin of different twins in the Kepler-107 exoplanet system
• Whole planet coupling between climate, mantle, and core: Implications for the evolution of rocky planets
• Carbon cycling and habitability of Earth-size stagnant lid planets
• The habitability of a stagnant-lid Earth
• Magma oceans and enhanced volcanism on TRAPPIST-1 planets due to induction heating
• No Evidence for Lunar Transit in New Analysis of Hubble Space Telescope Observations of the Kepler-1625 System
• The Pressure and Temperature Limits of Likely Rocky Exoplanets
• Terrestrial Planet Formation in the Presence of Migrating Super-earths
• Radii, masses, and ages of 18 bright stars using interferometry and new estimations of exoplanetary parameters
• Flaring activity of Proxima Centauri from TESS observations: quasi-periodic oscillations during flare decay and inferences on the habitability of Proxima b
• Studying stellar spin-down with Zeeman-Doppler magnetograms
• The Stellar Activity of TRAPPIST-1 and Consequences for the Planetary Atmospheres
• The Role of Carbon in Extrasolar Planetary Geodynamics and Habitability
• Terrestrial Planet Formation During the Migration and Resonance Crossings of the Giant Planets
• Effective induction heating around strongly magnetized stars
• Habitability of Earth-like stagnant lid planets: Climate evolution and recovery from snowball states
• Atmospheric Escape From TOI-700 d: Venus versus Earth Analogs
• Erosion of an exoplanetary atmosphere caused by stellar winds
• Predicting the Yield of Potential Venus Analogs from TESS and their Potential for Atmospheric Characterization
• Impact degassing and atmospheric erosion on Venus, Earth, and Mars during the late accretion
• Thorium in solar twins: implications for habitability in rocky planets
• Star-planet tidal interaction and the limits of gyrochronology

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• GJ 1252b: A Hot Terrestrial Super-Earth With No Atmosphere
• Oxygen False Positives on Habitable Zone Planets Around Sun-Like Stars
• Super-Earths and Earth-like Exoplanets
• The Fundamental Connections Between the Solar System and Exoplanetary Science
• Synergies between Venus & Exoplanetary Observations
• System-level fractionation of carbon from disk and planetesimal processing
• Hemispheric Tectonics on super-Earth LHS 3844b
• The Exosphere as a Boundary: Origin and Evolution of Airless Bodies in the Inner Solar System and Beyond Including Planets with Silicate Atmospheres
• Population-level Hypothesis Testing with Rocky Planet Emission Data: A Tentative Trend in the Brightness Temperatures of M-Earths
• A hot Mars-sized exoplanet transiting an M dwarf
• Orbital Dynamics and the Evolution of Planetary Habitability in the AU Mic System
• Phase Modeling of the TRAPPIST-1 Planetary Atmospheres
• Low 4.5 μm Dayside Emission Disfavors a Dark Bare-Rock scenario for the Hot Super-Earth TOI-431 b
• Variability of Known Exoplanet Host Stars Observed by TESS
• A Readily Implemented Atmosphere Sustainability Constraint for Terrestrial Exoplanets Orbiting Magnetically Active Stars
• TOI-4552 b: A new ultra-short period rocky world revealed by NIRPS and TESS
• Upper Limits on Planet-Induced GHz Radio Emission from Inactive M Dwarfs