Milankovitch Cycles for a Circumstellar Earth-analog within $\alpha$ Centauri-like Binaries

Abstract

An Earth-analog orbiting within the habitable zone of $\alpha$ Centauri B was shown to undergo large variations in its obliquity, or axial tilt, which affects the planetary climate by altering the radiative flux for a given latitude. We examine the potential implications of these obliquity variations for climate through Milankovitch cycles using an energy balance model with ice sheets. Similar to previous studies, the largest amplitude obliquity variations from spin-orbit resonances induce snowball states within the habitable zone, while moderate variations can allow for persistent ice caps or an ice belt. Particular outcomes for the global ice distribution can depend on the planetary orbit, obliquity, spin precession, binary orbit, and which star the Earth-analog orbits. An Earth-analog with an inclined orbits relative to the binary orbit can periodically transition through several global ice distribution states and risk runaway glaciation when periods of ice caps and an ice belt overlap. When determining the potential habitability for planets in stellar binaries, more care must be taken due to the orbital and spin dynamics.

25 pages, 16 figures, 1 table; fixed missing reference; accepted for publication in MNRAS; public repository at https://github.com/saturnaxis/Ice-ages-in-AlphaCen

References in corpus (12)

• The James Webb Space Telescope
• Habitable Zones Around Main-Sequence Stars: Dependence on Planetary Mass
• The Occurrence of Rocky Habitable Zone Planets Around Solar-Like Stars from Kepler Data
• The Habitable Exoplanet Observatory (HabEx) Mission Concept Study Final Report
• Effects of Extreme Obliquity Variations on the Habitability of Exoplanets
• The LUVOIR Mission Concept Study Final Report
• Orbital Stability of Circumstellar Planets in Binary Systems
• Precision Millimeter Astrometry of the $\alpha$ Centauri AB System
• Milankovitch Cycles of Terrestrial Planets in Binary Star Systems
• Planet formation in stellar binaries: Global simulations of planetesimal growth
• Long-Term Stability of Planets in the $\alpha$ Centauri System, II: Forced Eccentricities
• Evolution of $\alpha$ Centauri B's protoplanetary disc

Cited by in corpus (4)

• Sporadic Spin-Orbit Variations in Compact Multi-planet Systems and their Influence on Exoplanet Climate
• System Architecture and Planetary Obliquity: Implications for Long-Term Habitability
• An Energy Balance Model for Rapidly and Synchronously Rotating Terrestrial Planets
• Low Spin-Axis Variations of Circumbinary Planets