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EPoS |
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EPoS Contribution
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The High-resolution Accretion Disks of Embedded Protostars (HADES) simulations: Accretion flows onto embedded protostars
Brandt Gaches Chalmers, Gothenburg, SE | |
| How young, embedded protostars accrete their gas is still a matter of debate. Without a protostellar magnetic field, the disk can directly impact the surface of the protostar, dubbed "boundary layer accretion". Conversely, with strong protostar magnetic fields, the field may truncate the disk and enable gas to flow along magnetic flux tubes, dubbed "magnetospheric accretion". Simulations for the latter mechanism largely focus on weakly accreting evolved objects such as T-Tauris with accretion rates less than 10-8 Msun/yr. There has been a stark scarcity in high resolution accretion simulations during the embedded, protostar phases, when the accretion rate exceeds 10-6 Msun/yr. I will introduce the High-resolution Accretion Disks of Embedded protoStars (HADES) simulations, which are numerical experiments to investigate the accretion onto a solar mass protostar with accretion rates exceeding 10-6 Msun/yr with a maximal resolution of 10-4 AU. I will present the initial results on the accretion flow for a set of simulations with four different protostellar magnetic fields, 10 G, 500 G, 1000 G and 2000 G, combined with a disk magnetic field. I will show that the simulations highlight the role of the protostellar magnetic field in not only bifurcating the accretion flow and eventually truncating the disk, but also helping to focus the accretion flow towards the equator. For weak magnetic fields, the accretion occurs via a highly turbulent boundary layer mode. For moderate fields, the accretion mode oscillates between turbulent boundary layer and magnetospheric accretion due to pulsations in the magnetosphere. For strong fields, we recover magnetospheric accretion, albiet with a high degree of variability. In the future, these simulations will be used to produce important observables, in particular hydrogen recombination lines, and investigate the physical mechanics behind accretion powered outflows. | |
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| Caption: A zoom-in of the density distribution out to 1 AU for the case with a 500 G protostellar magnetic field, zooming down to the inner protostar surface boundary. | |
| Collaborators: J. Tan, Chalmers, SE R. Kuiper, Duisburg-EssenU, DE A. Rosen, SDSU, US |
Relevant topic(s): Accretion Low-Mass SF |
| Relevant Big Question: How do protostars accrete their gas? | |