|Time:||Thursday, September 30, 2021, 04:00pm|
|Title:||Novel views on planet formation and dust evolution: connecting protoplanetary disk demographics with exoplanets, debris disks and exoplanet atmospheres|
|Speaker:||Prof. Nienke van der Marel (Leiden)|
S727 & Online via Zoom
Structures such as gaps and rings in ALMA observations of protoplanetary disks have long been hailed as signposts of planet formation. However, a direct link between exoplanets and protoplanetary disks remained hard to identify. Recent work has shown that gapped disks retain high millimeter-dust masses up to at least 10 Myr, whereas the majority of disks is compact and decreases its dust mass rapidly. This can be understood when considering dust evolution, where dust traps prevent radial drift in the gapped disks. The fraction of gapped disks shows a stellar mass dependence, and I propose a scenario linking this dependence with that of giant exoplanet occurrence rates. It is shown that there are enough exoplanets to account for the observed disk structures if gapped disks are caused by exoplanets more massive than Neptune, under the assumption that most of those planets eventually migrate inwards. On the other hand, the known anti-correlation between transiting super-Earths and stellar mass implies those planets must form in the compact disks, consistent with those exoplanets forming through pebble accretion in drift-dominated disks. The gapped disks are also the most likely progenitors of debris disks around older stars, which has important consequences for disk evolution timescales. Finally, I will show that dust traps and radial drift may play a crucial role in regulating the chemical composition of disks, which sets the C/O ratio of exoplanet atmospheres as traced in the coming years with the James Webb Space Telescope.
Dr. Nienke van der Marel got her PhD cum laude in 2015 at Leiden Observatory in the Netherlands, with promotors Ewine van Dishoeck and Kees Dullemond. She was a Beatrice Watson Parrent Fellow at the University of Hawaii (USA) during 2015-2017, an NRC research fellow at NRC Herzberg Institute for Astronomy (Canada, BC) during 2017-2019 and a Banting fellow at the University of Victoria (Canada, BC) during 2019-2021. Since September 2021 she is an Assistant Professor at Leiden Observatory. Her research focuses on planet formation in protoplanetary disks. She works with submillimeter interferometric data, primarily from ALMA. Dr. Van der Marel has been at the forefront of the discovery and characterization of substructures in planet-forming disks. She analyzes both molecular line and continuum data through physical-chemical modeling with tools as RADMC-3D and DALI and compares observational data with theoretical models and exoplanet studies.
Host: Chris Ormel
Slides: 20210930-van der Marel.pdf