HD 163296: the violent coexistence of giant planets and planetesimals and its altering effects on protoplanetary disks
Abstract
Protoplanetary disks are the factory where, in the few Myr of their lifespan, dust and gas are quickly converted into the first generations of planetary bodies. High-precision radiometric dating of meteorites shows that even planetesimals large enough to melt and differentiate can appear in less than 1 Myr in disks. In parallel, high spatial resolution observations with the Atacama Large Millimetre/Submillimetre Array (ALMA) reveal a surprising morphological complexity of protoplanetary disks even at early stages, where gaps, rings and blobs are believed to be associated with the presence of young giant planets. The coexistence of young giant planets and planetesimals, however, is not peaceful: the strong gravity of the giant planets dynamically excites the orbits of the planetesimals and catapults them into a phase of intense and violent collisional evolution. In this work we show how the outcomes of this process can significantly affect the gas and dust populations of protoplanetary disk using HD 163296, one of the best characterized disks, as our case study. HD 163296 is a large and old protoplanetary disk hosting at least three giant planets and still possessing a high dust-to-gas ratio, notwithstanding the fact that most of its original dust should have already been converted into planetary bodies. Our results show that the collisional production of dust due to planetesimal impacts replenishes the decreasing first-generation dust population of the disk. The distribution of this second-generation dust is linked to the masses and orbital positions of the giant planets and affects the dust population not only quantitatively but also spatially, explaining the observed anomalous distribution inconsistent with its sole interaction with the gas. Finally, impact vaporization of the ices composing the planetesimals can produce altering effects on the gas through the introduction of non-equilibrium species, providing an explanation to the detected presence of DCO+ beyond the CO snowline. The overall picture emerging from our investigation of HD 163296 shows how the transition between protoplanetary disks and debris disks begins immediately after the appearance of giant planets in disks.
- Publication:
-
43rd COSPAR Scientific Assembly. Held 28 January - 4 February
- Pub Date:
- January 2021
- Bibcode:
- 2021cosp...43E.132T