Invited Presentation
Following the Gas into the Disk: Thick, Massive and Hot Protostellar Disks
Presenter: Jaime Pineda (Max-Planck-Institut für extraterrestrische Physik)
Recent observations are revealing that star and planet formation are not necessarily separate stages, but may already overlap during the deeply embedded Class 0/I phases. Yet, while the properties of more evolved Class II disks are now relatively well established, the physical conditions and dynamics of the youngest protostellar disks remain poorly constrained. In this talk, I will present ALMA observations at ~6 au resolution of a sample of young protostellar systems spanning different disk morphologies and multiplicities. By combining observations across multiple wavelengths, we find that these disks are remarkably optically thick, even at 3 mm, making it possible for early substructures associated with planet formation to remain hidden and implying disk masses that can approach or exceed the threshold for gravitational instability. At the same time, the observed brightness temperatures challenge the assumption that stellar irradiation alone determines the thermal structure of young disks, pointing instead to additional heating from accretion and shocks. These results highlight the importance of viewing protostellar disks as dynamic systems that are still being assembled and fed by their surrounding environment. Building an observation-based picture of how gas is delivered, processed, and heated during this phase is essential for understanding both stellar mass assembly and the conditions under which the first stages of planet formation may emerge.
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