Detection of Linearly Polarized 6.9 mm Continuum Emission from the Class
  0 Young Stellar Object NGC1333 IRAS4A
  We report new Karl G. Jansky Very Large Array (JVLA), 0$"$.5 angular
resolution observations of linearly polarized continuum emission at 6.9 mm,
towards the Class 0 young stellar object (YSO) NGC1333 IRAS4A. This target
source is a collapsing dense molecular core, which was resolved at short
wavelengths to have hourglass shaped B-field configuration. We compare these
6.9 mm observations with previous polarization Submillimeter Array (SMA)
observations at 0.88 mm, which have comparable angular resolution
($\sim$0$"$7). We found that at the same resolution, the observed polarization
position angles at 6.9 mm are slightly deviated from those observed at 0.88 mm.
Due to the lower optical depth of the emission at 6.9 mm, and the potential
effect of dust grain growth, the new JVLA observations are likely probing
B-field alignments in regions interior to those sampled by the previous
polarization observations at higher frequencies. Our understanding can be
improved by more sensitive observations, and observations for the more extended
spatial scales.
