Science

The SAINT-EX project is motivated by the fact that it is now possible to reach a precision of 100 ppm (parts per million) on the depth of a planetary transit around a V=6 star with a ground-based, 1-m class telescope thanks to the availability of a new generation of detectors: back-illuminated, deep depletion CCDs. SAINT-EX aims to search for and characterise transiting exoplanets in support of upcoming space missions and by focusing on ultra-cool stars, to enable the detection of small, Earth-size planets. SAINT-EX is a fully automated telescope.

Searching for rocky planets orbiting ultra-cool dwarfs

The recent discovery of TRAPPIST-1 (Gillon et al. 2016, Gillon et al. 2017) suggests that small planets are frequent around ultra-cool dwarfs (M5.5 to M9). This discovery indeed confirms that an untapped population of small planets exists around ultra-cool hosts. The interest in small planets orbiting ultra-cool dwarfs is justified by their enhanced detectability compared to Sun analogues and the unprecedented opportunity they offer for atmospheric characterisation of temperate, Earth-size planets with new facilities such as JWST. The SPECULOOS project, located in Cerro Paranal  (Chile) has started operations in 2017 and surveys the brightest ultra-cool stars in the Southern hemisphere. The first goal of SAINT-EX is to take part to this search and complement the survey of ultra-cool stars from the Northern hemisphere to search for small, rocky planets with equilibrium temperatures similar to the Earth and Venus.

SAINT-EX reaches the photometric precision to detect down to Mars-size planets orbiting in the habitable zone of the brightest ultra-cool dwarfs.

Follow-up of new exoplanets

SAINT-EX will also be employed to follow-up new exoplanet discoveries visible from the North. This includes new exoplanets from the NGTS and NASA TESS (launched 2018) surveys, among others. Additionally, SAINT-EX could be used in other science areas, such as long-term (and parallel) monitoring of exoplanet host star variability, which will be critical for high-precision transmission spectroscopy with JWST.
SAINT-EX also contributes to the science from the CHEOPS mission by proividing ground-based monitoring of selected targets at different wavelengths than the satellite. This enables in particular to identify the origin of light curve features detected at high precision with CHEOPS.