The birth process of circumstellar disks remains poorly constrained due to observational and numerical challenges. Recent numerical works have shown that the small-scale physics, often wrapped into a sub-grid model, play a crucial role in disk formation and evolution. This calls for a combined approach in which both the protostar and circumstellar disk are studied in concert.<\/p>\n\n\n\n
We aim to elucidate the small scale physics and constrain sub-grid parameters commonly chosen in the literature by resolving the star-disk interaction. We carry out a set of very high resolution 3D radiative-hydrodynamics simulations that self-consistently describe the collapse of a turbulent dense molecular cloud core to stellar densities. We study the birth of the protostar, the circumstellar disk, and its early evolution (< 6 yr after protostellar formation).<\/p>\n\n\n\n
Following the second gravitational collapse, the nascent protostar quickly reaches breakup velocity and sheds its surface material, thus forming a hot ( The circumstellar disk mass quickly exceeds that of the protostar, and its kinematics are dominated by self-gravity. Accretion onto the disk is highly anisotropic, and accretion onto the protostar mainly occurs through material that slides on the disk surface.<\/p>\n\n\n\n The polar mass flux is negligible in comparison. The radiative behavior also displays a strong anisotropy, as the polar accretion shock is shown to be supercritical whereas its equatorial counterpart is subcritical. We also find a remarkable convergence of our results with respect to initial conditions.<\/p>\n\n\n\n These results reveal the structure and kinematics in the smallest spatial scales relevant to protostellar and circumstellar disk evolution.<\/p>\n\n\n\n Recommended citation: Adnan Ali Ahmad, Mathias Gonz\u00e1lez, Patrick Hennebelle, Beno\u00eet Commer\u00e7on, A&A, 687, A90 (2024)<\/p>\n\n\n\n