On The Feasibility of Exomoon Detection Via Exoplanet Phase Curve Spectral Contrast

Abstract

An exoplanet-exomoon system presents a superposition of phase curves to observers - the dominant component varies according to the planetary period, and the lesser varies according to both the planetary and the lunar period. If the spectra of the two bodies differs significantly, then it is likely there are wavelength regimes where the contrast between the moon and planet is significantly larger. In principle, this effect could be used to isolate periodic oscillations in the combined phase curve. Being able to detect the exomoon component would allow a characterisation of the exomoon radius, and potentially some crude atmospheric data. We run a parameter survey of combined exoplanet-exomoon phase curves, which show that for most sets of planet-moon parameters, the lunar component of the phase curve is undetectable to current state-of-the-art transit observations. Even with future transit survey missions, measuring the exomoon signal will most likely require photometric precision of 10 parts per million or better. The only exception to this is if the moon is strongly tidally heated or in some way self-luminous. In this case, measurements of the phase curve at wavelengths greater than a few microns can be dominated by the lunar contribution. Instruments like the James Webb Space Telescope and its successors are needed to make this method feasible.

12 pages, 26 figures, accepted for publication by MNRAS

References in corpus (12)

• The generalised Lomb-Scargle periodogram. A new formalism for the floating-mean and Keplerian periodograms
• Transit timing effects due to an exomoon
• Hubble Space Telescope times-series photometry of the planetary transit of HD189733: no moon, no rings, starspots
• Detecting the Glint of Starlight on the Oceans of Distant Planets
• BGLS: A Bayesian formalism for the generalised Lomb-Scargle periodogram
• Variability in the Atmosphere of the Hot Giant Planet HAT-P-7 b
• Determination of the size, mass, and density of "exomoons" from photometric transit timing variations
• Detecting companions to extrasolar planets using mutual events
• On the detection of Exomoons: A search in Kepler data for the orbital sampling effect and the scatter peak
• Viscoelastic Models of Tidally Heated Exomoons
• Transit of Exomoon Plasma Tori: New Diagnosis
• Extrasolar Binary Planets II: Detectability by Transit Observations

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• Stability and detectability of exomoons orbiting HIP 41378 f, a temperate Jovian planet with an anomalously low apparent density
• Direct detectability of tidally heated exomoons by photometric orbital modulation
• Mean Motion Resonances With Nearby Moons: An Unlikely Origin For The Gaps Observed In The Ring Around The Exoplanet J1407b
• Enhanced thermal radiation from a tidally heated exomoon with a single hot spot