Motivation
The end of the 20th century was marked by some of the most fascinating astronomical discoveries of all times - the definite detection of extrasolar planets (or exoplanets) orbiting nearby stars. Somewhat surprisingly, exoplanets have revealed an astonishing diversity of forms, not known for our Solar System, such as rocky planets several times more massive than the Earth and gas giants ten times more massive than Jupiter. At the same time, the variety of the known planetary systems has deeply challenged the formation theories developed to explain the origin of the Solar System.
Formation of exoplanets can be explained within the context of two distinct and somewhat competing scenarios. The disk instability model requires a gravitationally unstable circumstellar disk to form a gaseous clump by means of disk gravitational fragmentation. The clump later contracts to form a giant gaseous planet and a solid core may form in its interior owing to accretion of dust particles from the disk. On the other hand, in the core-accretion model, small dust particles coagulate to form terrestrial planets and solid cores, the latter may continue accreting gaseous envelopes to form giant planets.
Both theory an observations suggest that the planet formation process may start very early, soon after the formation of a young stellar object (YSO) consisting of a circumstellar disk, parental cloud and host star. The disk properties in the early phase are poorly known from observations because disks are deeply embedded in parental clouds and opaque to a broad spectrum of electromagnetic radiation. The lack of high spatial and spectral resolution data had also been a hindrance until recently. This will change with ALMA, the Atacama Large Millimeter/submillimeter Array, the world’s largest interferometer array, whose construction was finished this year. Therefore, it is important to use join efforts of both theorists and observers to derive the properties of planet-forming disks.
Due to heavy numerical load, existing numerical codes cannot follow the entire process of planet formation, starting from disk formation and ending with the emergence of a planetary system. Instead, they focus either on the early stages, studying the properties of protostellar disks but oversimplifying the planet formation and evolution, or on investigating the dynamics of already formed planets in the late stage, skipping the process of disk formation. In the latter case, simplified disk configurations are usually taken as initial conditions. However, the planet dynamics strongly depend on the physical properties of their parental disks. It is therefore of fundamental importance to model the planet evolution using the most realistic disk configurations. Now we have the opportunity to develop the modeling process and use the most advanced observational techniques simultaneously, hand-in-hand.
Proposal Objectives
The main objective of our proposal is to study the evolution of planets in self-gravitating disks typical for the early evolution of YSOs, with the ultimate purpose to explain the observed diversity of extrasolar planets. In recent investigations the project members have successfully applied the YSO-Evol code to model the star and disk formation and the GFARGO code to model planet-disk interactions. In this project, the Austrian partners will provide physically realistic disk configurations, which will later be used by the Hungarian partners for studying the planet formation and evolution.
During the project, both codes will be modified and improved. First, the GFARGO code (Hungarian partners) will be modified to include the effect of disk self-gravity based on the algorithm developed and employed by the Austrian partners in their YSO-Evol code. Since GFARGO is a fully GPU-based code, which enables high-performance computing using graphical processor units (GPUs), our new implementation of self-gravity solver will be also GPU-enabled. As a next step, we will include the GPU-implementation of the self-gravity solver into the YSO-Evol code. This will allow us to greatly increase our productivity because GPUs can provide a factor of ten acceleration compared to conventional CPUs. As a final step of the project, we intend to compare our numerical predictions to the high spatial resolution observations. We already have in hand data from the Plateau de Bure Interferometer (PdBI), and have an accepted proposal for ALMA, with currently ongoing observations.
Project Details
The research plan of our project entitled Selbstkonsistente Modellierung der Entstehung und Evolution von Planeten-I: OMAA_90öu25_ResearchPlan.pdf. Members of the research group are E. Vorobyov, A. Kóspál, and Zs. Regály. The research project was jointly funded by the Bundesministerium für Wissenschaft und Forschung and Magyar Művelődési és Közoktatási Minisztérium in 2016. The total budget of this four year project is EUR 5 000.
Publications
An alternative model for the origin of gaps in circumstellar disks
Vorobyov, E. I.; Regály, Zs.; Guedel, M; Lin, D. N. C.
2016, A&A, Volume 587, 146 12 pp.;
ADS:2016A&6A...587A.146V
arXiv:1601.08089
The circumstellar disk response to the motion of the host star
Regály, Zs.; E. Vorobyov, 2017
2017A&A...601A..24R
arXiv:170104751R
