Abstract
The 1000 nearest ultra-cool stars (spectral type M6 and latter) represent a unique opportunity to the search for life beyond our solar system. Due to their small luminosity, their habitable zone is 30-100 times closer than for the Sun, the corresponding orbital periods ranging from one to a few days. Thanks to this proximity, the transits of habitable planets are much more probable and frequent than for Earth-Sun analogs. The tiny size of these stars (about 1 Jupiter radius) makes the transits of Earth-sized planets deep enough for a ground-based detection. Furthermore, a habitable planet transiting one of these nearby ultra-cool stars would be amenable for a thorough atmospheric characterization, including the detection of possible biosignatures, notably with the future JWST. Motivated by these facts, we have set up a photometric survey optimized for detecting planets of Earth-size and below transiting the nearest Southern ultra-cool stars. The name of this project is SPECULOOS (Search for habitable Planets Eclipsing ULtra-cOOl Stars), and it will consist in several robotic 1m-class telescopes that will operate from the Chilean Atacama Desert from 2015. The talk will present the concept and status of SPECULOOS, and some results of its prototype operating from Chile since 2011.