arXiv subjects

Andrey G. Zhilkin

Publications and source records attributed to Andrey G. Zhilkin.

3 recordsLinked to original sources

arXiv2022

Primary disks and their observational appearance in collapsing magnetic rotating protostellar clouds

The collapse of the magnetic rotating protostellar cloud with mass of $10\,M_{\odot}$ is numerically studied. The initial ratios of the thermal, magnetic, and rotational energies of the cloud to the modulus of its gravitational energy are 0.3, 0.2 and 0.01, respectively. The emphasis is on the evolution and properties of the quasi-magnetostatic primary disk formed at the isothermal stage of the collapse. Simulations show that the primary disk size and mass increase during evolution from $1500$ au to $7400$ au and from $0.3\,M_{\odot}$ to $5.2\,M_{\odot}$, respectively. Magnetic field is quasi-radial in the cloud envelope and quasi-uniform within the primary disk. A toroidal magnetic field is generated behind the front of the fast shock MHD wave propagating from the primary disk boundary and in the region of the outflow formed near the first hydrostatic core. The hierarchical structure of collapsing protostellar clouds can be revealed in observations in terms of the magnetic field geometry and the angular momentum distribution.

astro-ph.SR↗

arXiv2022

Simulations of the isothermal collapse of magnetic rotating protostellar clouds

We investigate collapse of magnetic protostellar clouds of mass $10$ and $1 M_{\odot}$. The collapse is simulated numerically using the two-dimensional magnetohydrodynamic (MHD) code `Enlil'. The simulations show that protostellar clouds acquire a hierarchical structure by the end of the isothermal stage of collapse. Under the action of the electromagnetic force, the protostellar cloud takes the form of an oblate envelope with the half-thickness to radius ratio $Z/R \sim (0.20-0.95)$. A geometrically and optically thin primary disk with radius $0.2-0.7 R_0$ and $Z/R \sim (10^{-2}-10^{-1})$ forms inside the envelope, where $R_0$ is the initial radius of the cloud. Primary disks are the structures in magnetostatic equilibrium. They form when the initial magnetic energy of the cloud exceeds $20 \%$ of its gravitational energy. The mass of the primary disk is $30-80 \%$ of the initial mass of the cloud. The first hydrostatic core subsequently forms in the center of the primary disc. We discuss the role of primary disks in the further evolution of clouds, as well as possible observational appearance of the internal hierarchy of the collapsing cloud from the point of view of the features of the magnetic field geometry and the distribution of angular momentum at different levels of the hierarchy

astro-ph.GA↗

arXiv2001

TVD Scheme for the Numerical Simulation of the Axisymmetrical Selfgravitating MHD Flows

The explicit quasi-monotonic conservative TVD scheme and numerical method for the solution of the gravitational MHD equations are developed. The 2D numerical code for the simulation of multidimensional selfgravitating MHD flows on the Eulerian cylindrical grid is constructed. The results of test calculations show that the code has a good mathematical and computational properties and can be applied to the solution of a wide class of plasma physics and astrophysics problems. We have simulated, for example, a collapse of magnetized rotating protostellar clouds.

astro-ph↗