Amelia Bayo, European Southern Observatory (ESO), Garching, Germany — July 15, 2024

The classical and simplistic (but to some extent correct) view of star and planet formation describes the gravitational collapse of an isolated core, followed by the coexistence of an envelope and disk structure. Since the emergence of a protoplanetary disk occurs quasi simultaneously with that of the star, it could be expected that the star would dominate the orientation of the spin axis of the system so that stars, disks and planets would display coplanar configurations. However, evidence on misalignments between the inner and outer disk components have been reported in several cases, as well as significant mutual inclinations among planets and recently among stars and debris disks.

Mechanisms invoked to explain this departure from coplanarity and their relation to disk and planet formation have been recently grouped onto three categories: primordial, post planet formation and independent of the planet formation process. Each of these kinds of mechanisms have predictions that operate different time scales and system properties. In this pilot study we focus on a sample of protoplanetary disk systems with large cavities (so called transition disks) and show that no individual mechanism can explain the mutual inclinations found between disks (and subparts of them) and their host stars at this evolutionary stage.

In addition I will spend part of the talk introducing the soon-to-arrive Multi Object Optical and Near-infrared Spectrograph for the VLT (MOONS). MOONS can spread its ~950 fibers over the full Field of View of UT1; it observes simultaneously in RI, YJ and H bands with low or medium resolution. Currently the instrument is being integrated at the ATC and we are conducting operations and performance tests with the goal to "ship" to Paranal early in Q4 of this year. I will quickly mention the GTO science cases and the way the community can already prepare to exploit this unique instrument.