Modeling the secular evolution of embedded protoplanetary discs

Abstract

Context: Protoplanetary discs are known to form around nascent stars from their parent molecular cloud as a result of angular momentum conservation. As they progressively evolve and dissipate, they also form planets. While a lot of modeling efforts have been dedicated to their formation, the question of their secular evolution, from the so-called class 0 embedded phase to the class II phase where discs are believed to be isolated, remains poorly understood. Aims: We aim to explore the evolution between the embedded stages and the class II stage. We focus on the magnetic field evolution and the long-term interaction between the disc and the envelope. Methods: We use the GPU-accelerated code \textsc{Idefix} to perform a 3D, barotropic, non-ideal magnetohydrodynamic (MHD) secular core collapse simulation that covers the system evolution from the collapse of the pre-stellar core until 100 kyr after the first hydrostatic core formation and the disc settling while ensuring sufficient vertical and azimuthal resolutions (down to $10^{-2}$ au) to properly resolve the disc internal dynamics and non-axisymmetric perturbations. Results: The disc evolution leads to a power-law gas surface density in Keplerian rotation that extends up to a few 10 au. The magnetic flux trapped in the disc during the initial collapse decreases from 100 mG at disc formation down to 1 mG by the end of the simulation. After the formation of the first hydrostatic core, the system evolves in three phases. A first phase with a small ($\sim 10$ au), unstable, strongly accreting ($\sim10^{-5}$ $\mathrm{M_\odot \, yr^{-1}}$) disc that loses magnetic flux over the first 15 kyr, a second phase where the magnetic flux is advected with a smooth, expanding disc fed by the angular momentum of the infalling material...