Nov 13, 2020
The JCMT BISTRO survey: alignment between outflows and magnetic fields in dense cores/clumps
The Astrophysical Journal
- Volume
- 907
- Number
- 1
- First page
- 33
- Last page
- 33
- Language
- Publishing type
- Research paper (scientific journal)
- DOI
- 10.3847/1538-4357/abca99
- Publisher
- American Astronomical Society
We compare the directions of molecular outflows of 62 low-mass Class 0 and I
protostars in nearby (<450 pc) star-forming regions with the mean orientations
of the magnetic fields on 0.05-0.5 pc scales in the dense cores/clumps where
they are embedded. The magnetic field orientations were measured using the JCMT
POL-2 data taken by the BISTRO-1 survey and from the archive. The outflow
directions were observed with interferometers in the literature. The observed
distribution of the angles between the outflows and the magnetic fields peaks
between 15 and 35 degrees. After considering projection effects, our results
could suggest that the outflows tend to be misaligned with the magnetic fields
by 50+/-15 degrees in three-dimensional space and are less likely (but not
ruled out) randomly oriented with respect to the magnetic fields. There is no
correlation between the misalignment and the bolometric temperatures in our
sample. In several sources, the small-scale (1000-3000 au) magnetic fields is
more misaligned with the outflows than their large-scale magnetic fields,
suggesting that the small-scale magnetic field has been twisted by the
dynamics. In comparison with turbulent MHD simulations of core formation, our
observational results are more consistent with models in which the energy
densities in the magnetic field and the turbulence of the gas are comparable.
Our results also suggest that the misalignment alone cannot sufficiently reduce
the efficiency of magnetic braking to enable formation of the observed number
of large Keplerian disks with sizes larger than 30-50 au.
protostars in nearby (<450 pc) star-forming regions with the mean orientations
of the magnetic fields on 0.05-0.5 pc scales in the dense cores/clumps where
they are embedded. The magnetic field orientations were measured using the JCMT
POL-2 data taken by the BISTRO-1 survey and from the archive. The outflow
directions were observed with interferometers in the literature. The observed
distribution of the angles between the outflows and the magnetic fields peaks
between 15 and 35 degrees. After considering projection effects, our results
could suggest that the outflows tend to be misaligned with the magnetic fields
by 50+/-15 degrees in three-dimensional space and are less likely (but not
ruled out) randomly oriented with respect to the magnetic fields. There is no
correlation between the misalignment and the bolometric temperatures in our
sample. In several sources, the small-scale (1000-3000 au) magnetic fields is
more misaligned with the outflows than their large-scale magnetic fields,
suggesting that the small-scale magnetic field has been twisted by the
dynamics. In comparison with turbulent MHD simulations of core formation, our
observational results are more consistent with models in which the energy
densities in the magnetic field and the turbulence of the gas are comparable.
Our results also suggest that the misalignment alone cannot sufficiently reduce
the efficiency of magnetic braking to enable formation of the observed number
of large Keplerian disks with sizes larger than 30-50 au.
- Link information
- ID information
-
- DOI : 10.3847/1538-4357/abca99
- eISSN : 1538-4357
- arXiv ID : arXiv:2011.06731