Highly Ordered and Pinched Magnetic Fields in the Class 0 Protobinary System L1448 IRS 2Kwon, W., Stephens, I. W., Tobin, J. J., Looney, L. W., Li, Z-Y., van der Tak, F. F. S. & Crutcher, R. M., 1-Jul-2019, In : The Astrophysical Journal. 879, 1
Research output: Contribution to journal › Article › Academic › peer-review
We have carried out polarimetric observations with the Atacama Large Millimeter/submillimeter Array toward the Class 0 protostellar system L1448 IRS 2, which is a protobinary embedded within a flattened, rotating structure, and for which a hint of a central disk has been suggested, but whose magnetic fields are aligned with the bipolar outflow on the cloud core scale. Our high-sensitivity and high- resolution (̃100 au) observations show a clear hourglass magnetic field morphology centered on the protostellar system, but the central pattern is consistent with a toroidal field indicative of a circumstellar disk; though, other interpretations are also possible, including field lines dragged by an equatorial accretion flow into a configuration parallel to the midplane. If a relatively large disk does exist, it would suggest that the magnetic braking catastrophe is averted in this system, not through a large misalignment between the magnetic and rotation axes, but rather through some other mechanisms, such as nonideal magnetohydrodynamic effects and/or turbulence. We have also found a relationship of decreasing polarization fractions with intensities and the various slopes of this relationship can be understood as multiple polarization mechanisms and/or depolarization from a changing field morphology. In addition, we found a prominent clumpy depolarization strip crossing the center perpendicular to the bipolar outflow. Moreover, a rough estimate of the magnetic field strength indicates that the field is strong enough to hinder formation of a rotationally supported disk, which is inconsistent with the feature of a central toroidal field. This also suggests that early disk formation can happen even in young stellar objects with a strong primordial magnetic field.
|Journal||The Astrophysical Journal|
|Publication status||Published - 1-Jul-2019|
- magnetic fields, stars: formation, stars: protostars, submillimeter: ISM, Astrophysics - Solar and Stellar Astrophysics, Astrophysics - Astrophysics of Galaxies