Abstract
ABSTRACT An exomoon on a non-perfectly circular orbit experiences tidal heating that is capable to significantly contribute to the thermal brightness of the moon. Here we argue that the thermal heat is unevenly distributed on the moon’s surface, the emission of the tidal heat is limited to a few hotspots on the surface. A well-known example is the tidally heated Io. Due to their significantly increased temperature, the hotspots enhance the energy emission in thermal wavelengths. We made simulations using Monte Carlo method to examine this contribution, and to predict about the possible detectability of such a spotted exomoon. We found that in the case of large, Earth-sized companions to Jupiters around red dwarf stars exhibit a thermal flux that enables the direct detection of the moon, due to its photometric signal that can exceed ≈100 ppm in the most favourable configurations.
Highlights
Exoplanets observation history has been extending to three decades, but no confirmed exomoon has found yet
We argue that the thermal heat is unevenly distributed on the moon’s surface, the emission of the tidal heat is limited to a few hot spots on the surface
We found that in the case of large, Earth sized companions to jupiters around red dwarf stars exhibit a thermal flux that enables the direct detection of the moon, due to its photometric signal that can exceed ≈100 ppm in the most favourable configurations
Summary
Exoplanets observation history has been extending to three decades, but no confirmed exomoon has found yet. Teachey et al (2017) described a candidate Neptune sized exomoon orbiting the Jupiter-sized exoplanet Kepler-1625b, which still needs to be confirmed (Heller et al 2019) Indirect methods, such as accounting for a TTV of the planet caused by the gravity of the moon was suggested by Sartoretti & Schneider (1999). Reynolds et al (1987); Scharf (2006); Heller & Barnes (2013) found that due to tidal heating, a moon can be heated up to high temperatures enough to support a habitable environment even very far from the star If this heating is very effective, the heated moon can be warm enough to support a detection in an eclipse or a moon-to-planet transit, or in occultation.
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