Extracting physical properties of barely-resolvedprotoplanetary disks using visibilities

The field of planet formation is undergoing rapid development, mostly thanks to the transformational capabilities of ALMA. The vertical height (z(r)) is one of the fundamental properties needed for constraining disk formation and evolution. For example, extracting z(r) in different isotopologues tells us about the vertical structure of disks. Z(r) can be extracted from molecular emission, mostly CO, observed with ALMA, but it is critical to have analysis tools capable of retrieving all the information hidden in the data in a reliable way. Usually, disk radii have been measured from the CO images and only for a limited number of bright and extended disks. In interferometry, however, images are highly processed data products, and this introduces systematic biases which are difficult to quantify. I will present a new strategy which retrieves z(r) directly in the visibilities, the native quantity measured by the interferometer. The analysis, implemented in the code CSALT (Andrews et al., in prep.), is based on a parametric model of the disc structure and emission; this approach allows a robust statistical inference of the model parameters. In this talk, I will present preliminary results obtained with this new technique for a subset of barely resolved protoplanetary disks retrieved from the ALMA archive. I will show the results on my analysis for different molecular tracers, and show how this new technique allows us to robustly extract z(r) for observations with moderate ang res.