Seminario: High-contrat imaging at the VLT: from SPHERE to SPHERE+

Speakers: Charles Goulas & Johan Mazoyer (LESIA / Paris Observatory)
 
Abstract: Of the 5,000 exoplanets currently known, less than 1% have been detected by direct imaging. But by allowing the simultaneous observation of young circumstellar disks and planets often not detectable by other techniques, this method is a fundamental tool for understanding the stages of the formation of planetary systems. In addition, direct access to the light of all detected objects opens the way to widespread chemical and thermal analyses of exoplanetary atmospheres and surfaces. However, direct imaging faces a specific challenge: accessing objects whose flux ratio with their star can reach 10-10 (for telluric planets), and which are only separated by a fraction of an arcsecond. The objective of coronagraphic instruments is precisely to produce such high-contrast observations. Most large telescopes are equipped with coronagraphs: Gemini, Subaru and Keck as well as HST and JWST in space. 
 
One of the most productive imagers is the Spectro-Polarimetic High contrast imager for Exoplanets REsearch (SPHERE), installed at the ESO Very Large Telescope (VLT) for almost a decade. The achievements obtained thus far with SPHERE (more than 200 refereed publications) in different areas (exoplanets, disks, solar system, stellar physics...) have motivated a large consortium to propose an even more ambitious set of science cases, and its corresponding technical implementation in the form of an upgrade. The SPHERE+ project that we will present in this talk capitalizes on the expertise and lessons learned from SPHERE to push high-contrast imaging performance to its limits on the VLT 8m-telescope.