Fifty AU Study of the chemistry and physics of proto-Sun analogues (FAUST): Initial Results

One of the major questions of modern science is how atoms ended up forming the Solar System, the Earth, and life. We know that a crucial step is the formation of the Solar nebula disk. However, we do not know at what precise stage the disk formed and how matter chemically evolved during the disk formation. Recent studies on Solar-type protostars show that the transition from an infalling-rotating envelope to a rotationally supported disk occurs on scales of about 50 au in the young protoatellar ages (≤105 yr). This transition can be accompanied by a drastic chemical change and significant growth of dust grains. In this context, we are conducting the ALMA large program FAUST, in which we observe 13 Class 0/I Solar-type protostars with the goal to fully characterize their physical and chemical structures at 50 au scales. We will answer the following four specific and related questions: (1) disentangle the physical components of the 50—2000 au envelope/disk system; (2) characterize the organic complexity in each of them; (3) probe their ionization structure; (4) measure their molecular deuteration. The output will be a homogeneous database of thousands of images from different lines and species, i.e. an unprecedented source-survey of the chemical diversity of Solar-like protostars on 50 au scales. FAUST will thus provide the community with a legacy dataset that will be a milestone for astrochemistry and star formation studies. After the first publications on L1551 and IRAS15398 (Bianchi et al. 2020; Okoda et al. 2021), the analysis of the FAUST sample is steadily in progress. In this talk, I am going to present some initial highlights.