Jets and outflows of massive protostars – From cloud collapse to jet launching and cloud dispersal. (arXiv:1811.07009v1 [astro-ph.SR])
<a href="http://arxiv.org/find/astro-ph/1/au:+Kolligan_A/0/1/0/all/0/1">Anders Kölligan</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kuiper_R/0/1/0/all/0/1">Rolf Kuiper</a>
In a comprehensive convergence study, we investigate the computational
conditions necessary to resolve disk formation and jet-launching processes, and
analyze possible caveats. We explore the magneto-hydrodynamic (MHD) processes
of the collapse of massive prestellar cores in detail, including an analysis of
the forces involved and their temporal evolution for up to two free-fall times.
We conduct MHD simulations, combining nonideal MHD, self-gravity, and very high
resolutions as they have never been achieved before. Our setup includes a 100
Msol cloud core that collapses under its own self-gravity to self-consistently
form a dense disk structure and launch tightly collimated magneto-centrifugal
jets and wide-angle winds. Our high-resolution simulations can resolve a
magneto-centrifugal jet and a magnetic pressure-driven outflow, separately. The
nature of the outflows depends critically on spatial resolution. Only
high-resolution simulations are able to differentiate a magneto-centrifugally
launched, highly collimated jet from a slow wide-angle magnetic-pressure-driven
tower flow. Of these two outflow components, the tower flow dominates
angular-momentum transport. The mass outflow rate is dominated by the entrained
material from the interaction of the jet with the stellar environment and only
part of the ejected medium is directly launched from the accretion disk. A
tower flow can only develop to its full extent when much of the original
envelope has already dispersed. Taking into account both the mass launched from
the surface of the disk and the entrained material from the envelope, we find
an ejection-to-accretion efficiency of 10%. Nonideal MHD is required to form
centrifugally supported accretion disks and the disk size is strongly dependent
on spatial resolution.
In a comprehensive convergence study, we investigate the computational
conditions necessary to resolve disk formation and jet-launching processes, and
analyze possible caveats. We explore the magneto-hydrodynamic (MHD) processes
of the collapse of massive prestellar cores in detail, including an analysis of
the forces involved and their temporal evolution for up to two free-fall times.
We conduct MHD simulations, combining nonideal MHD, self-gravity, and very high
resolutions as they have never been achieved before. Our setup includes a 100
Msol cloud core that collapses under its own self-gravity to self-consistently
form a dense disk structure and launch tightly collimated magneto-centrifugal
jets and wide-angle winds. Our high-resolution simulations can resolve a
magneto-centrifugal jet and a magnetic pressure-driven outflow, separately. The
nature of the outflows depends critically on spatial resolution. Only
high-resolution simulations are able to differentiate a magneto-centrifugally
launched, highly collimated jet from a slow wide-angle magnetic-pressure-driven
tower flow. Of these two outflow components, the tower flow dominates
angular-momentum transport. The mass outflow rate is dominated by the entrained
material from the interaction of the jet with the stellar environment and only
part of the ejected medium is directly launched from the accretion disk. A
tower flow can only develop to its full extent when much of the original
envelope has already dispersed. Taking into account both the mass launched from
the surface of the disk and the entrained material from the envelope, we find
an ejection-to-accretion efficiency of 10%. Nonideal MHD is required to form
centrifugally supported accretion disks and the disk size is strongly dependent
on spatial resolution.
http://arxiv.org/icons/sfx.gif
