  The magnetic field plays an important role in every stage of the
star-formation process from the collapse of the initial protostellar core to
the star's arrival on the main sequence. Consequently, the goal of this science
case is to explore a wide range of magnetic phenomena that can be investigated
using the polarization capabilities of the Next Generation Very Large Array
(ngVLA). These include (1) magnetic fields in protostellar cores via polarized
emission from aligned dust grains, including in regions optically thick at
wavelengths observable by the Atacama Large Millimeter/submillimeter Array
(ALMA); (2) magnetic fields in both protostellar cores and molecular outflows
via spectral-line polarization from the Zeeman and Goldreich-Kylafis effects;
(3) magnetic fields in protostellar jets via polarized synchrotron emission;
and (4) gyrosynchrotron emission from magnetospheres around low-mass stars.

Astrophysics of Galaxies;Solar and Stellar Astrophysics