On the feasibility of exomoon detection via exoplanet phase curve spectral contrast

Forgan, Duncan

doi:10.1093/mnras/stx1217

Cited by 41 publications

(14 citation statements)

References 42 publications

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“…This could be obtained if the moon is sufficiently bright compared to the planet at wavelengths of interest. Proposed techniques for obtaining exomoon spectral data involve spectroastrometry (Agol et al, 2015), oscillations in the combined exoplanet-exomoon phase curve (Forgan, 2017), or radial velocity measurements of the exoplanet using high dispersion spectroscopy (Brogi & Forgan, in prep. ).…”

Section: Discussionmentioning

confidence: 99%

The habitable zone for Earth-like exomoons orbiting Kepler-1625b

Forgan

2019

International Journal of Astrobiology

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The recent announcement of a Neptune-sized exomoon candidate orbiting the Jupiter-sized object Kepler-1625b has forced us to rethink our assumptions regarding both exomoons and their host exoplanets. In this paper I describe calculations of the habitable zone for Earthlike exomoons in orbit of Kepler-1625b under a variety of assumptions. I find that the candidate exomoon, Kepler-1625b-i, does not currently reside within the exomoon habitable zone, but may have done so when Kepler-1625 occupied the main sequence. If it were to possess its own moon (a "moon-moon") that was Earthlike, this could potentially have been a habitable world. If other exomoons orbit Kepler-1625b, then there are a range of possible semimajor axes/eccentricities that would permit a habitable surface during the main sequence phase, while remaining dynamically stable under the perturbations of Kepler-1625b-i. This is however contingent on effective atmospheric CO2 regulation.

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Section: Discussionmentioning

confidence: 99%

The habitable zone for Earth-like exomoons orbiting Kepler-1625b

Forgan

2019

International Journal of Astrobiology

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“…This tendency for an exomoon to have warmer poles due to planetary illumination suggests that such bodies may have a greater fractional habitable area than Earth today (Spiegel et al 2008), potentially improving the prospects of an origin of life (Heller & Armstrong 2014). This prediction of polar warming on exomoons could eventually translate into observables from the circumstellar phase curves of an exomoon, if the planet's contribution to the combined planet-moon phase curve can be filtered out (Cowan et al 2012;Forgan 2017).…”

Section: Discussionmentioning

confidence: 99%

Exploring exomoon atmospheres with an idealized general circulation model

Haqq-Misra

Heller

2018

Monthly Notices of the Royal Astronomical Society

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Recent studies have shown that large exomoons can form in the accretion disks around super-Jovian extrasolar planets. These planets are abundant at about 1 AU from Sunlike stars, which makes their putative moons interesting for studies of habitability. Technological advances could soon make an exomoon discovery with Kepler or the upcoming CHEOPS and PLATO space missions possible. Exomoon climates might be substantially different from exoplanet climates because the day-night cycles on moons are determined by the moon's synchronous rotation with its host planet. Moreover, planetary illumination at the top of the moon's atmosphere and tidal heating at the moon's surface can be substantial, which can affect the redistribution of energy on exomoons. Using an idealized general circulation model with simplified hydrologic, radiative, and convective processes, we calculate surface temperature, wind speed, mean meridional circulation, and energy transport on a 2.5 Mars-mass moon orbiting a 10-Jupiter-mass at 1 AU from a Sun-like star. The strong thermal irradiation from a young giant planet causes the satellite's polar regions to warm, which remains consistent with the dynamically-driven polar amplification seen in Earth models that lack ice-albedo feedback. Thermal irradiation from young, luminous giant planets onto water-rich exomoons can be strong enough to induce water loss on a planet, which could lead to a runaway greenhouse. Moons that are in synchronous rotation with their host planet and do not experience a runaway greenhouse could experience substantial polar melting induced by the polar amplification of planetary illumination and geothermal heating from tidal effects.

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“…As most potentially habitable exoplanets discovered already (Proxima b, TRAPPIST‐1 planets, etc.) and to be discovered (TESS planets for example) are orbiting around M dwarfs, we also carry out retrieval analysis for hypothetical exoplanets‐exomoons around M dwarfs by using the observed photon spectrum of GJ667C (France et al, 2016), scaled to the orbital distance of GJ667Cc (red in Figure 2). For this group of targets a distance of 6.8 pc is assumed.…”

Section: Methodsmentioning

confidence: 99%

“…Gómez-Leal et al (2012) suggests that because the lowest few km of the Earth are unseen in thermal emission, diurnal variations of exoplanets could be masked in thermal emission and thus the phase variations of exoplanet-exo-moon systems could be dominated by exomoon signals. Forgan (2017) found that distinguishing the lunar component of the thermal emission phase curve of most exoplanet-exomoon systems will require a photometric precision of 10 -5 . In this work we focus on the reflection spectra of exoplanet-exomoon systems instead of the thermal emission.…”

Section: Methodsmentioning

confidence: 99%

Simultaneous characterization of the atmospheres, surfaces, and exomoons of nearby rocky exoplanets

Cui¹,

Zhang²,

Cui³

et al. 2018

Earth and Planetary Physics

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Atmospheric composition is an important indicator of habitability and life. The presence or absence of a large exomoon around an Earth‐size exoplanet could have important consequences for planet climate stability. Thus the detection of exomoons and retrieval of information regarding atmospheric composition of Earth‐size exoplanets are important goals of future exoplanet observations. Here a data analysis method is developed to achieve both goals simultaneously, based on reflection spectra of exoplanet‐exomoon systems. We show that the existence of exomoons, the size of exomoons, and the concentrations of some atomic and molecular species in the atmospheres of their hosting Earth‐like exoplanets can be retrieved with high levels of reliability. In addition, the method can provide well‐constrained fractions of basic surface types on the targets because of the characteristic spectral features of atmospheric species and surface types in the analyzed spectral range.

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On the feasibility of exomoon detection via exoplanet phase curve spectral contrast

Cited by 41 publications

References 42 publications

The habitable zone for Earth-like exomoons orbiting Kepler-1625b

The habitable zone for Earth-like exomoons orbiting Kepler-1625b

Exploring exomoon atmospheres with an idealized general circulation model

Simultaneous characterization of the atmospheres, surfaces, and exomoons of nearby rocky exoplanets

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