Periodic Reporting for period 4 - DustPrints (Dusting for the Fingerprints of Planet Formation)
Reporting period: 2021-09-01 to 2023-06-30
Despite the over 4000 planets that have been detected up to today, surprisingly we are still struggling to answer even the most basic questions about how planets form, for example: How fast do they form? Do they form by gradual growth or by fast collapse? Recent observations with the ALMA Radio Telescope Array allow us to study the cradles of planet formation in unprecedented resolution. It has revealed never-before seen substructure that remains to be explained. Are the rings and gaps we see caused by planets or are they caused by something else but enable planets to form? In this project, we want to make use of the new observational capabilities and use novel theoretical models to interpret them to unravel some of the mysteries around how planets form.
The project has two sides: one is focusing on international collaborations to obtain and process new observational data. The other side focuses on building new theoretical concepts and numerical simulation software. To answer some of the fundamental questions on planet formation, we need to combine both sides and interpret and analyze the newest observations with state-of-the-art theory and simulations. We have build computer codes to simulate how small solid particles collide and grow or fragment and how they are transported and eventually concentrated in protoplanetary disks to eventually form the building blocks of planets. The developed software package has been publicly released. At the same time, we have combined these methods with hydrodynamical simulations that simulate the early stages of planet formation where for the first time, we take into account the gas dynamics and the evolution and growth of the particles. With this tool, we have to re-evaluate many of the earlier studies that did not properly include those effects. We also developed novel data analysis techniques that for the first time allowed us to show that the structures that are observed match the predictions of planets through their influence on both the solids and the gas. At the same time, in a larger collaboration, we published the first large sample of 20 planet forming disks that all show substructures. Taken together, this shows that planets are likely responsible for most if not all of the structure observed in disks. Surprisingly, they seem to have formed very early which challenges us to develop new theoretical ideas of how nature is able to do this. Our theoretical models showed that the observed sub-structures in disks are consistent with the planetary building block being assembled there. In our latest simulations, we were able to show how massive planets can form as quickly as observations surprisingly indicated.
The numerical models, the new observational results, and also the data analysis that was developed during this project are pushing the state of the art and have lead to crucial new insights that have substantially influenced the field of planet formation and have attracted the interest of the general public in two well-received press releases. Our main findings were that sub-structures in disks are very common, that planets are the cause for most of these structures. This means that planets form much faster than previously though and we have developed models that are able to explain how planets form that quickly.