CHEOPS performance for exomoons: The detectability of exomoons by using optimal decision algorithm

Abstract

Many attempts have already been made for detecting exomoons around transiting exoplanets but the first confirmed discovery is still pending. The experience that have been gathered so far allow us to better optimize future space telescopes for this challenge, already during the development phase. In this paper we focus on the forthcoming CHaraterising ExOPlanet Satellite (CHEOPS),describing an optimized decision algorithm with step-by-step evaluation, and calculating the number of required transits for an exomoon detection for various planet-moon configurations that can be observable by CHEOPS. We explore the most efficient way for such an observation which minimizes the cost in observing time. Our study is based on PTV observations (photocentric transit timing variation, Szabó et al. 2006) in simulated CHEOPS data, but the recipe does not depend on the actual detection method, and it can be substituted with e.g. the photodynamical method for later applications. Using the current state-of-the-art level simulation of CHEOPS data we analyzed transit observation sets for different star-planet-moon configurations and performed a bootstrap analysis to determine their detection statistics. We have found that the detection limit is around an Earth-sized moon. In the case of favorable spatial configurations, systems with at least such a large moon and with at least Neptune-sized planet, 80\% detection chance requires at least 5-6 transit observations on average. There is also non-zero chance in the case of smaller moons, but the detection statistics deteriorates rapidly, while the necessary transit measurements increase fast. (abridged)

32 pages, 14 figures, accepted for publication in PASP

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Cited by in corpus (17)

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• The Effect of Multiple Heat Sources on Exomoon Habitable Zones
• The Exomoon Corridor: Half of all exomoons exhibit TTV frequencies within a narrow window due to aliasing
• Large planets may not form fractionally large moons
• Modeling the Orbital Sampling Effect of Extrasolar Moons
• On the ultraviolet anomalies of the WASP-12 and HD 189733 systems: Trojan satellites as a plasma source
• On The Feasibility of Exomoon Detection Via Exoplanet Phase Curve Spectral Contrast
• On the Detection of Extrasolar Moons and Rings
• A full transit of ${\nu }^2$ Lupi d and the search for an exomoon in its Hill sphere with CHEOPS
• Terminus: A Versatile Simulator for Space-based Telescopes
• Traces of exomoons in computed flux and polarization phase curves of starlight reflected by exoplanets
• Exploring exomoon atmospheres with an idealized general circulation model
• The "Drake equation" of exomoons -- a cascade of formation, stability and detection
• The CHEOPS view of HD 95338b: refined transit parameters, and a search for exomoons
• Special cases : moons, rings, comets, trojans