The Impact of Planetary Rotation Rate on the Reflectance and Thermal Emission Spectrum of Terrestrial Exoplanets Around Sun-like Stars

Abstract

Robust atmospheric and radiative transfer modeling will be required to properly interpret reflected light and thermal emission spectra of terrestrial exoplanets. This will help break observational degeneracies between the numerous atmospheric, planetary, and stellar factors that drive planetary climate. Here we simulate the climates of Earth-like worlds around the Sun with increasingly slow rotation periods, from Earth-like to fully Sun-synchronous, using the ROCKE-3D general circulation model. We then provide these results as input to the Spectral Planet Model (SPM), which employs the SMART radiative transfer model to simulate the spectra of a planet as it would be observed from a future space-based telescope. We find that the primary observable effects of slowing planetary rotation rate are the altered cloud distributions, altitudes, and opacities which subsequently drive many changes to the spectra by altering the absorption band depths of biologically-relevant gas species (e.g., H2O, O2, and O3). We also identify a potentially diagnostic feature of synchronously rotating worlds in mid-infrared H2O absorption/emission lines.

Accepted to The Astrophysical Journal

References in corpus (34)

• The Transiting Exoplanet Survey Satellite
• Seven temperate terrestrial planets around the nearby ultracool dwarf star TRAPPIST-1
• A terrestrial planet candidate in a temperate orbit around Proxima Centauri
• Thermal structure of an exoplanet atmosphere from phase-resolved emission spectroscopy
• The Pale Orange Dot: The Spectrum and Habitability of Hazy Archean Earth
• Was Venus the First Habitable World of our Solar System?
• The habitability of Proxima Centauri b II. Possible climates and Observability
• Strong Dependence of the Inner Edge of the Habitable Zone on Planetary Rotation Rate
• Kepler-62: A five-planet system with planets of 1.4 and 1.6 Earth radii in the Habitable Zone
• Observing the Atmospheres of Known Temperate Earth-sized Planets with JWST
• The Detectability and Characterization of the TRAPPIST-1 Exoplanet Atmospheres with JWST
• Tidal Locking of Habitable Exoplanets
• Asynchronous rotation of Earth-mass planets in the habitable zone of lower-mass stars
• Carbon monoxide and water vapor in the atmosphere of the non-transiting exoplanet HD 179949 b
• Atmospheric characterization of Proxima b by coupling the Sphere high-contrast imager to the Espresso spectrograph
• Spectral Fingerprints of Earth-like Planets Around FGK Stars
• Atmospheric dynamics of terrestrial exoplanets over a wide range of orbital and atmospheric parameters
• Validation of Twelve Small Kepler Transiting Planets in the Habitable Zone
• Treatment of overlapping gaseous absorption with the correlated-k method in hot Jupiter and brown dwarf atmosphere models
• Detection of Ocean Glint and Ozone Absorption Using LCROSS Earth Observations
• DARWIN - A Mission to Detect, and Search for Life on, Extrasolar Planets
• Transition to a Moist Greenhouse with CO${}_2$ and solar forcing
• Constraints on Climate and Habitability for Earth-like Exoplanets Determined from a General Circulation Model
• A temperate exo-Earth around a quiet M dwarf at 3.4 parsecs
• Deciphering thermal phase curves of dry, tidally locked terrestrial planets
• Water Trapping on Tidally Locked Terrestrial Planets Requires Special Conditions
• TRAPPIST-1 Habitable Atmosphere Intercomparison (THAI). Motivations and protocol version 1.0
• Ocean Dynamics and the Inner Edge of the Habitable Zone for Tidally Locked Terrestrial Planets
• Simulations of Water Vapor and Clouds on Rapidly Rotating and Tidally Locked Planets: a 3D Model Intercomparison
• Atmospheric Retrieval for Direct Imaging Spectroscopy of Gas Giants In Reflected Light II: Orbital Phase and Planetary Radius
• Stratosphere circulation on tidally locked ExoEarths
• Dynamics of atmospheres with a non-dilute condensible component
• Detecting Proxima b's atmosphere with JWST targeting CO2 at 15 micron using a high-pass spectral filtering technique
• Antiprotons Produced in Supernova Remnants

Cited by in corpus (4)

• Variability due to climate and chemistry in observations of oxygenated Earth-analogue exoplanets
• Sporadic Spin-Orbit Variations in Compact Multi-planet Systems and their Influence on Exoplanet Climate
• Atmospheric Dynamics of a Near Tidally Locked Earth-Size Planet
• Increased Surface Temperatures of Habitable White Dwarf Worlds Relative to Main-Sequence Exoplanets