Characterizing Magnetic Properties of Young Protostars in Orion

The B-field Orion Protostellar Survey (BOPS) recently obtained polarimetric observations at 870 m towards 61 protostars in the Orion molecular clouds with 1^ spatial resolution using the Atacama Large Millimeter/submillimeter Array. From the BOPS sample, we selected the 26 protostars with extended polarized emission within a radius of 6^ (2400~au) around the protostar. This allows to have sufficient statistical polarization data to infer the magnetic field strength. The magnetic field strength is derived using the Davis-Chandrasekhar-Fermi method. The underlying magnetic field strengths are approximately 2. 0~mG for protostars with a standard hourglass magnetic field morphology, which is higher than the values derived for protostars with rotated hourglass, spiral, and complex magnetic field configurations (1. 0~mG). This suggests that the magnetic field plays a more significant role in envelopes exhibiting a standard hourglass field morphology, and a value of 2. 0 mG would be required to maintain such a structure at these scales. Furthermore, most protostars in the sample are slightly supercritical, with mass-to-flux ratios 3. 0. In particular, the mass-to-flux ratios for all protostars with a standard hourglass magnetic field morphology are lower than 3. 0. However, these ratios do not account for the contribution of the protostellar mass, which means they are likely significantly underestimated.