Absence of a Runaway Greenhouse Limit on Lava Planets
arXiv:2505.11149 · doi:10.3847/1538-4357/add69f
Abstract
Climate transitions on exoplanets offer valuable insights into the atmospheric processes governing planetary habitability. Previous pure-steam atmospheric models show a thermal limit in outgoing long-wave radiation, which has been used to define the inner edge of the classical habitable zone and guide exoplanet surveys aiming to identify and characterize potentially habitable worlds. We expand upon previous modelling by treating (i) the dissolution of volatiles into a magma ocean underneath the atmosphere, (ii) a broader volatile range of the atmospheric composition including H2O, CO2, CO, H2, CH4 and N2, and (iii) a surface temperature- and mantle redox-dependent equilibrium chemistry. We find that multi-component atmospheres of outgassed composition located above partially or fully-molten mantles do not exhibit the characteristic thermal radiation limit that arises from pure-steam models, thereby undermining the canonical concept of a runaway greenhouse limit, and hence challenging the conventional approach of using it to define an irradiation-based habitable zone. Our results show that atmospheric heat loss to space is strongly dependent on the oxidation and melting state of the underlying planetary mantle, through their significant influence on the atmosphere's equilibrium composition. This suggests an evolutionary hysteresis in climate scenarios: initially molten and cooling planets do not converge to the same climate regime as solidified planets that heat up by external irradiation. Steady-state models cannot recover evolutionary climate transitions, which instead require self-consistent models of the temporal evolution of the coupled feedback processes between interior and atmosphere over geologic time.
arXiv commentAccepted for publication in ApJ
References in corpus (56)
- Array Programming with NumPy
- Habitable Zones Around Main-Sequence Stars: New Estimates
- Transiting exoplanets from the CoRoT space mission VIII. CoRoT-7b: the first Super-Earth with measured radius
- Habitable planets around the star Gl 581?
- Stabilizing Cloud Feedback Dramatically Expands the Habitable Zone of Tidally Locked Planets
- Hydrogen Greenhouse Planets Beyond the Habitable Zone
- Formation of planetary systems by pebble accretion and migration: How the radial pebble flux determines a terrestrial-planet or super-Earth growth mode
- Dynamics of pebbles in the vicinity of a growing planetary embryo: hydro-dynamical simulations
- Theoretical models of planetary system formation: mass vs semi-major axis
- The New Generation Planetary Population Synthesis (NGPPS). I. Bern global model of planet formation and evolution, model tests, and emerging planetary systems
- Predictions of the atmospheric composition of GJ 1132b
- The Habitable Zones of Pre-Main-Sequence Stars
- Day-night cloud asymmetry prevents early oceans on Venus but not on Earth
- Tidal heating of Earth-like exoplanets around M stars: Thermal, magnetic, and orbital evolutions
- The Frequency of Giant impacts on Earth-like Worlds
- A secondary atmosphere on the rocky exoplanet 55 Cancri e
- The Elemental Abundances (with Uncertainties) of the Most Earth-like Planet
- A Volcanic Hydrogen Habitable Zone
- Revised mass-radius relationships for water-rich rocky planets more irradiated than the runaway greenhouse limit
- Exploring the Habitable Zone for Kepler planetary candidates
- Retention of water in terrestrial magma oceans and carbon-rich early atmospheres
- Linking the evolution of terrestrial interiors and an early outgassed atmosphere to astrophysical observations
- Atmospheres of Rocky Exoplanets
- Water on Hot Rocky Exoplanets
- The New Generation Planetary Population Synthesis (NGPPS). III. Warm super-Earths and cold Jupiters: A weak occurrence correlation, but with a strong architecture-composition link
- The evolution of habitable zones during stellar lifetimes and its implications on the search for extraterrestrial life
- Vertically resolved magma ocean-protoatmosphere evolution: H, HO, CO, CH, CO, O, and N as primary absorbers
- Distinguishing oceans of water from magma on mini-Neptune K2-18b
- Scaling laws for the geometry of an impact-induced magma ocean
- Solubility of water in peridotite liquids and the prevalence of steam atmospheres on rocky planets
- A Methane Extension to the Classical Habitable Zone
- Lava Worlds: From Early Earth to Exoplanets
- Magma oceans as a critical stage in the tectonic development of rocky planets
- Redox hysteresis of super-Earth exoplanets from magma ocean circulation
- Susceptibility of planetary atmospheres to mass loss and growth by planetesimal impacts: the impact shoreline
- The erosion of large primary atmospheres typically leaves behind substantial secondary atmospheres on temperate rocky planets
- A cool runaway greenhouse without surface magma ocean
- Super-Earths and Earth-like Exoplanets
- The distribution of volatile elements during rocky planet formation
- Hot Hydrogen Climates near the inner edge of the Habitable Zone
- Water Condensation Zones around Main Sequence Stars
- The Fundamental Connections Between the Solar System and Exoplanetary Science
- Direct imaging of molten protoplanets in nearby young stellar associations
- Beyond runaway: initiation of the post-runaway greenhouse state on rocky exoplanets
- Magma ocean evolution at arbitrary redox state
- Anatomy of rocky planets formed by rapid pebble accretion II. Differentiation by accretion energy and thermal blanketing
- Bioverse: The Habitable Zone Inner Edge Discontinuity as an Imprint of Runaway Greenhouse Climates on Exoplanet Demographics
- Reduced late bombardment on rocky exoplanets around M-dwarfs
- How does Background Air Pressure Influence the Inner Edge of the Habitable Zone for Tidally Locked Planets in a 3D View?
- How does the background atmosphere affect the onset of the runaway greenhouse ?
- Convective shutdown in the atmospheres of lava worlds
- The effect of high nitrogen pressures on the habitable zone and an appraisal of greenhouse states
- Thermal and orbital evolution of low-mass exoplanets
- The influence of surface condensation on the evolution of warm and cold rocky planets orbiting Sun-like stars
- CO ocean bistability on terrestrial exoplanets
- Large Interferometer For Exoplanets (LIFE). XIV. Finding terrestrial protoplanets in the galactic neighborhood