On the Direct Imaging of Tidally Heated Exomoons

Abstract

We demonstrate the ability of existing and planned telescopes, on the ground and in space, to directly image tidally heated exomoons orbiting gas-giant exoplanets. Tidally heated exomoons can plausibly be far more luminous than their host exoplanet and as much as 0.1% as bright as the system's stellar primary if it is a low mass star. Because emission from exomoons can be powered by tidal forces, they can shine brightly at arbitrarily large separations from the system's stellar primary with temperatures of several hundreds degrees Kelvin or even higher in extreme cases. Furthermore, these high temperatures can occur in systems that are billions of years old. Tidally heated exomoons may thus be far easier targets for direct imaging studies than giant exoplanets which must be both young and at a large projected separation from their primary to be accessible to current generation direct imaging studies. For example, the (warm) Spitzer Space Telescope and the next generation of ground based instruments could detect an exomoon roughly the size of the Earth at a temperature ~600K and a distance ~5 parsecs. Future mid-infrared space telescopes, such as JWST and SPICA, will be capable of directly imaging tidally heated exomoons around the nearest two dozen stars with brightness temperature >300K and R>1R_earth orbiting at >12AU from the primary star at a 5sigma confidence level in a 10,000 second integration. In addition it is possible that some of the exoplanets which have already been directly imaged are actually tidally heated exomoons or blends of such objects with hot young planets. If such exomoons exist and are sufficiently common (i.e. nearby), it may well be far easier to directly image an exomoon with surface conditions that allow the existence of liquid water than it will be to resolve an Earth-like planet in the classical Habitable Zone of its primary.

Accepted to ApJ on April 12th, 2013

References in corpus (13)

• Direct Imaging of Multiple Planets Orbiting the Star HR 8799
• Transit timing effects due to an exomoon
• Direct Imaging Discovery of a `Super-Jupiter' Around the late B-Type Star Kappa And
• Direct Imaging Confirmation and Characterization of a Dust-Enshrouded Candidate Exoplanet Orbiting Fomalhaut
• Determination of the size, mass, and density of "exomoons" from photometric transit timing variations
• N-body Simulations of Satellite Formation around Giant Planets: Origin of Orbital Configuration of the Galilean Moons
• Exomoon habitability constrained by energy flux and orbital stability
• The potential for tidally heated icy and temperate moons around exoplanets
• Two nearby sub-Earth-sized exoplanet candidates in the GJ 436 system
• Eccentricity evolution in hierarchical triple systems with eccentric outer binaries
• Conceptual Design of the Coronagraphic High Angular Resolution Imaging Spectrograph (CHARIS) for the Subaru Telescope
• Eccentricity generation in hierarchical triple systems with coplanar and initially circular orbits
• Scientific Design of a High Contrast Integral Field Spectrograph for the Subaru Telescope

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• Viscoelastic Models of Tidally Heated Exomoons
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• Exomoon Habitability and Tidal Evolution in Low-Mass Star Systems
• Orbital instability of close-in exomoons in non-coplanar systems
• A Systematic Search for Trojan Planets in the Kepler data
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• The Effect of Multiple Heat Sources on Exomoon Habitable Zones
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• The Effect of Planetary Illumination on Climate Modelling of Earthlike Exomoons
• Exomoon Climate Models with the Carbonate-Silicate Cycle and Viscoelastic Tidal Heating
• On The Feasibility of Exomoon Detection Via Exoplanet Phase Curve Spectral Contrast
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• uGMRT observations of the hot-Saturn WASP 69b: Radio-Loud Exoplanet-Exomoon Survey II (RLEES II)
• On the Detection of Extrasolar Moons and Rings
• Next Generation of Telescopes or Dynamics Required to Determine if Exo-Moons have Prograde or Retrograde Orbits
• The TEMPO Survey I: Predicting Yields of the Transiting Exosatellites, Moons, and Planets from a 30-day Survey of Orion with the Nancy Grace Roman Space Telescope
• Stability and detectability of exomoons orbiting HIP 41378 f, a temperate Jovian planet with an anomalously low apparent density
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• Constraining the period of the ringed secondary companion to the young star J1407 with photographic plates
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• Collisional formation of massive exomoons of super-terrestrial exoplanets
• Tidally Heated Exomoons around $\epsilon$ Eridani b: Observability and prospects for characterization
• Direct detectability of tidally heated exomoons by photometric orbital modulation
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• Astrophysical Simulations and Data Analyses on the Formation, Detection, and Habitability of Moons Around Extrasolar Planets
• Enhanced thermal radiation from a tidally heated exomoon with a single hot spot
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