The Compositional Diversity of Low-Mass Exoplanets

Abstract

Low-mass planets have an extraordinarily diverse range of bulk compositions, from primarily rocky worlds to those with deep gaseous atmospheres. As techniques for measuring the masses of exoplanets are advancing the field towards the terrestrial regime, from ultra-short orbital periods to Venus-like distances, we identify the bounds on planet compositions, where sizes and incident fluxes inform bulk planet properties. In some cases, measurement precisions of planet masses and sizes are approaching the theoretical uncertainties in planet models. An emerging picture explains aspects of the diversity of low-mass planets although some problems remain; do extreme low density low-mass planets challenge models of atmospheric mass loss? Are planet sizes strictly separated by bulk composition? Why do some stellar characterizations differ between observational techniques? As the TESS mission begins, low-mass exoplanets around the nearest stars will soon be discovered and characterized with unprecedented precision, permitting more detailed planetary modeling and atmospheric characterization of low mass exoplanets than ever before.

31 pages, 8 figures

References in corpus (26)

• A terrestrial planet candidate in a temperate orbit around Proxima Centauri
• DHP Framework: Digital Health Passports Using Blockchain -- Use case on international tourism during the COVID-19 pandemic
• Mass-Radius Relationships for Solid Exoplanets
• Most 1.6 Earth-Radius Planets are not Rocky
• KEPLER's First Rocky Planet: Kepler-10b
• The Mass of KOI-94d and a Relation for Planet Radius, Mass, and Incident Flux
• A Study of the Shortest-Period Planets Found With Kepler
• The Atmospheric Signatures of Super-Earths: How to Distinguish Between Hydrogen-Rich and Hydrogen-Poor Atmospheres
• Observing the Atmospheres of Known Temperate Earth-sized Planets with JWST
• The Mass of Kepler-93b and The Composition of Terrestrial Planets
• A resonant chain of four transiting, sub-Neptune planets
• HAT-P-26b: A Neptune-Mass Exoplanet with a Well Constrained Heavy Element Abundance
• Trends in Atmospheric Properties of Neptune-Size Exoplanets
• A Dynamical Analysis of the Kepler-80 System of Five Transiting Planets
• The mass of the Mars-sized exoplanet Kepler-138 b from transit timing
• Stellar activity mimics a habitable-zone planet around Kapteyn's star
• Using Transit Timing Observations to Search for Trojans of Transiting Extrasolar Planets
• Bayesian analysis of interiors of HD 219134b, Kepler-10b, Kepler-93b, CoRoT-7b, 55 Cnc e, and HD 97658b using stellar abundance proxies
• Accretion and Evolution of ~2.5 Earth-mass Planets with Voluminous H/He Envelopes
• Dusty tails of evaporating exoplanets. I. Constraints on the dust composition
• The discovery and mass measurement of a new ultra-short-period planet: EPIC~228732031b
• Precise Masses in the WASP-47 System
• An Overabundance of Low-density Neptune-like Planets
• The Effect of Conjunctions on the Transit Timing Variations of Exoplanets
• Vulcan Planets: Inside-Out Formation of the Innermost Super-Earths
• Average Albedos of Close-in Super-Earths and Neptunes from Statistical Analysis of Long Cadence Kepler Secondary Eclipse Data

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• Beyond runaway: initiation of the post-runaway greenhouse state on rocky exoplanets
• Possible Atmospheric Diversity of Low Mass Exoplanets, some Central Aspects
• Reduced late bombardment on rocky exoplanets around M-dwarfs
• Discovery and mass measurement of the hot, transiting, Earth-sized planet GJ 3929 b
• Ions in the Thermosphere of Exoplanets: Observable Constraints Revealed by Innovative Laboratory Experiments
• TESS Observations of Kepler systems with Transit Timing Variations
• A differentiable N-body code for transit timing and dynamical modeling. I. Algorithm and derivatives
• Fundamental effective temperature measurements for eclipsing binary stars -- III. SPIRou near-infrared spectroscopy and CHEOPS photometry of the benchmark G0V star EBLM J0113+31
• Coralie radial-velocity search for companions around evolved stars (CASCADES) III. A new Jupiter host-star: in-depth analysis of HD 29399 using TESS data
• ROME (Radio Observations of Magnetized Exoplanets). II. HD 189733 Does Not Accrete Significant Material from its Exoplanet like a T Tauri Star from A Disk
• Mass Derivation of planets K2-21b and K2-21c from Transit Timing Variations
• A Multi-Planet System's Sole Super-Puff: Exploring Allowable Physical Parameters for the Cold Super-Puff HIP 41378 f