Cycle 7: Joint HAWC+/ALMA Investigation of Young Protostars in Ophiuchus

Using ALMA, the superb new international astronomical facility in Chile, astronomers are at the threshold of directly observing the process of planet formation, thereby stimulating intense research activity by theorists and observers worldwide. However, stubborn puzzles remain, including the "magnetic braking catastrophe" which refers to our failure to understand what stops magnetic forces from funneling all disk material directly into the nascent star. Proper tests of theories that address this puzzle will require observations of magnetic fields over a very wide range of spatial scales. The nearby rich stellar nurseries in Ophiuchus, just 125 parsecs away, provide a unique opportunity to carry out such tests. By combining polarimetry data from the Planck satellite, the HAWC+ far-IR polarimeter on SOFIA, and ALMA, we can trace magnetic fields nearly continuously over more than four orders of magnitude in spatial scale. Here we propose to complete our HAWC+/SOFIA observations of a sample of eight protostars, chosen from a larger sample of 14 bright protostellar targets selected for ALMA polarimetry that is now underway. Our results will test whether magnetic field misalignment is important for disk formation and allow field strength estimates, both of which are key unknown factors that strongly affect the formation of disks around protostars.