Direct imaging of exoplanets

Details. The detection of extrasolar planets is one of the most exciting goals of modern astronomy. Direct imaging is the only technique that efficiently probe the distribution of gaseous giant exoplanets on wide orbits (> 5au) and is therefore complementary to the methods based on radial velocities and transits, which are most sensitive to exoplanets close to their hosting star. State-of-the-art extreme Adaptive Optics (ExAO)-assisted instruments, such as SPHERE and GPI, can provide contrasts down to 10^-5-10^-6  in the near-infrared at angular separations larger than ~100-150 mas, i.e. typically >10-20au from their parent star. Despite these remarkable performances, the total number of directly imaged planets still amounts to only about 20, likely because the bulk of the population of giant planets form at separation smaller than 10-20 au by core accretion. Improving the contrast capabilities at very small angular separations is therefore a fundamental step to characterize the population of giant planets. By observing at optical wavelengths SHARK-VIS will benefit from improved angular resolution (λ/D ~ 20 mas) and will give us the unique opportunity to probe very young planets (<10 Myr) still in formation within their parental disk by using their Hα line emission, which is a tracer of gas accretion and offers a much enhanced contrast with respect to the optical continuum. SHARK-VIS Hα observations will allow us to observe the planet formation phase and the interaction between planets and protoplanetary disks, which is essential to ultimately set constraints on the mechanisms and time-scales of planet formation and draw a picture of the assembly of planetary system architectures. The huge potential of the Hα observations has been testified by the recent detection of two actively accreting planets within the disk of the young PDS-70 system. The main scientific program of SHARK-VIS, which will be carried out in synergy with the companion instrument SHARK-NIR, is focused on the search and characterization of planetary mass companions of young sources in the Taurus-Auriga star-forming region.