by- 25 April 2014 ( maj : 25 November 2016 )
More than a thousand exoplanets have been detected around other stars than our sun. Most of them have been observed using indirect techniques of observation using either the stellar flux or the stellar radial velocity variation periodically induced by the presence of an orbiting planet. These techniques are currently limited to the close-in planets at less than 5 AU. To date, only a tens of exoplanets have been directly imaged.
The SPHERE instrument, installed at the ESO Very Large Telescope at Paranal (Chile), aims at imaging and characterizing giant exoplanets around stars close to the Sun. SPHERE represents a huge technological and scientific challenge as planets are very faint and very close to their star and therefore difficult to detect.
SPHERE is designed to optimally suppress the stellar light without removing the planetary signal using high-contrast and high-angular resolution techniques. To compensate the effect of the atmosphere, SPHERE is equipped with an adaptive optics system to restore the ultimate spatial resolution of the telescope as if the Telescope was in Space. Then, combining various techniques of coronagraphy and differential imaging, SPHERE optimized the detection of the planets in imaging, but also the characterization of the planet’s orbital and chemical properties.
SPHERE is currently on the UT3 Telescope of the ESO Paranal observatory. The instrument had its first light in May 2014 and has been offered to the community in early-2015. Combining technological and scientific challenges, SPHERE is one of the most innovant ground-based instrument built to date. The consortium to conduct the SPHERE project consists of 12 major European astronomy institutes.