ALMA revolutionised our comprehension of planet formation, unveiling the presence of rings and gaps in disks, a possible signature of dust grain growth and/or young protoplanets embedded in the disk. These substructures have been detected also in the disk of the young (<500,000 years) protostar IRS 63, a Class I source located in the nearby Ophiuchus molecular cloud, suggesting that planet formation occurs early, in disks of less than 1 Myr.
In parallel, ALMA is also revolutionising our comprehension of the disk chemistry, which is crucial to understand what chemical composition planets inherit from their natal environment.
In the context of the ALMA Large Programme FAUST (Fifty AU STudy of the chemistry in the disk/envelope system of Solar-like protostars; 2018.1.01205.L, PI: S. Yamamoto), we present observations of single and doubly deuterated formaldehyde (HDCO and D2CO) in the disk of IRS 63. Molecular deuteration is a powerful tool to trace back the history of the Solar System as the deuterium fraction in molecular species, such as formaldehyde, is enhanced in cold prestellar cores and may then be inherited by the protostellar disk and delivered to the nascent planets. We compare our estimate of the deuterium fraction in H2CO in the disk of IRS 63 with the values obtained for prestellar cores, Class 0 and I protostars, and comets, to discuss the inheritance of chemical complexity from the cold prestellar phases to young planet-forming disks.