The Protostars in Orion: Characterizing the Properties of Their Magnetized Envelopes

We present a study connecting the physical properties of protostellar envelopes to the morphology of the envelope-scale magnetic field. We used the Atacama Large Millimeter/submillimeter Array (ALMA) polarization observations of 61 young protostars at 0.87 mm on ~400-3000 au scales from the B-field Orion Protostellar Survey to infer the envelope-scale magnetic field, and we used the dust emission to measure the envelope properties on comparable scales. We find that protostars showing standard hourglass magnetic field morphology tend to have larger masses, and the nonthermal velocity dispersion is positively correlated with the bolometric luminosity and dust temperature of the envelope. Combining with the disk properties taken from the Orion VLA/ALMA Nascent Disk and Multiplicity survey, we connect envelope properties to fragmentation. Our results show a positive correlation between the fragmentation level and the angle dispersion of the magnetic field, suggesting that the envelope fragmentation tends to be suppressed by the magnetic field. We also find that protostars exhibiting standard hourglass magnetic field structure tend to have a smaller disk and smaller angle dispersion of the magnetic field than other field configurations, especially the rotated hourglass, but also the spiral and others, suggesting a more effective magnetic braking in the standard hourglass morphology of magnetic fields. Nevertheless, significant misalignment between the magnetic field and outflow axes tends to reduce magnetic braking, leading to the formation of larger disks.