EPoS Contribution
EPoS Contribution
Bimodality of Circumstellar Disk Evolution Induced by the Hall Current

Yusuke Tsukamoto
In this study, we investigate the effect of the Hall current term on the formation of the circumstellar disk using three-dimensional simulations. In our simulations, all non-ideal effects, as well as the radiation transfer, are considered. The size of the disk is significantly affected by a simple difference in the inherent properties of the prestellar core, namely whether the rotation vector and the magnetic field are parallel or anti-parallel. In the former case, only a very small disk (< 1 AU) is formed. On the other hand, in the latter case, a massive and large (> 20 AU) disk is formed in the early phase of protostar formation. Since the parallel and anti-parallel properties do not readily change, we expect that the parallel and anti-parallel properties are also important in the subsequent disk evolution and the difference between the two cases is maintained or enhanced. This result suggests that the disk size distribution of the Class 0 young stellar objects is bimodal. Thus, the disk evolution can be categorized into two cases and we may call the parallel and anti-parallel systems Ortho-disk and Para-disk, respectively. We also show that the counter-rotating envelopes against the disk rotation appear with a size of ≥ 200 AU. We predict that the counter-rotating envelope will be found in the future observations.
Caption: Density map of newborn disks formed in the cloud core with parallel configuration (left, model Ortho) and anti-parallel configuration (right, model Para). This figure is taken from figure 1 of Tsukamoto+ (2015) but it has been modified to clarify the formation of the disk in the model Ortho. In the simulations, all non-ideal effects are considered. The only difference between the initial condition of the model Ortho and Para is the direction of the magnetic field. The upper left figure in the left panel shows the enlarged density map around the center of the model Ortho. It shows that that a disk with a size of ~ 1 AU is formed at the center in the parallel case. The right panel shows that a disk with a size of ~ 20 AU is formed at the center in the anti-parallel case. We confirmed that both disks are rotationally supported. The non-axisymmetric spiral arms in right panel are due to gravitational instability. In addition, Toomre's Q value was confirmed to be Q ~ 1.
M.N. Machida, Kyushu U, JP
S. Inutsuka, Nagoya U, JP
K. Iwasaki, Doshisha U, JP
S. Okuzumi, Titec, JP
Key publication

Suggested Session: Disk Formation