The PEBBLES project has focused on obtaining observations and develop models to characterize the properties of dust grains in yourg embedded protostars, at the epoch disks are forming and evolving towards planet-forming disks.
Regarding models, we have successfully developed both a dynamical model to follow dust solid particles evolution (aggregation into larger particles) during the collapse of protostellar dense cores, and structural models to predict the optical properties of aggregate dust grains predicted by the dynamical models.
These two efforts are original and novel research, as no such models had been developed prior to PEBBLES. They show that the the complex structure of dust grains, which shape and sizes evolve greatly during the disk assembly stages, needs to be taken into account when interpreting astronomical observations of the dense environments where stars and planets form.
Several observing programs to trace the thermal dust emission at submillimeter and milleter wavelengths have been carried out in 2024-2025, allowing to trace the evolution of dust properties from the dense ISM to the birthplaces of protoplanetary disks. They are either published, or about to be published. Following up on the early results, multi-wavelength observations are now being analyzed to constrin simultaneously the dust temperature and its emissivity, a key to lift degenracies.
A large program using the IRAM/NOEMA observatory has been kicked off, with first observations carried out in the Winter of 2024, allowing for the first time to probe the dust polarized emission at 3mm, at scales 100 au. While the scientific analysis is ongoing, it shows already several unexpected results, suggesting that further investigations about the early dust evolution and dust alignment mechanisms, must be carried out.
