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

Simon, Attila and Szabó M., Gyula and Kiss, L. László and Fortier, A. and Benz, W. (2015) CHEOPS performance for exomoons : The detectability of exomoons by using optimal decision algorithm. PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC, 127 (956). pp. 1084-1095. ISSN 0004-6280

Preview

Text 1508.00321.pdf Available under License Creative Commons Attribution. Download (1MB) | Preview

Abstract

Many attempts have already been made for detecting exomoons around transit- ing 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 forth- coming 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 observ- able 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 (photo- centric transit timing variation, Szab´o 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 mea- surements increase fast. After the CoRoT and Kepler spacecrafts, CHEOPS will be the next dedicated space telescope that will observe exoplanetary transits and characterize systems with known Doppler-planets. Although it has smaller aperture than Kepler (the ratio of the mirror diameters is about 1/3) and is mounted with a CCD that is similar to Kepler’s, it will observe brighter stars and operate with larger sampling rate, therefore the detection limit for an exomoon can be the same as or better, which will make CHEOPS, a competitive instruments in the quest for exomoons.

Actions (login required)

Edit Item