Formation and Evolution of Disks Around Young Stellar Objects.

Recent observations have suggested that circumstellar disks may commonly form around young stellar objects. Although the formation of circumstellar disks can be a natural result of the conservation of angular momentum in the parent cloud, theoretical studies instead show disk formation to be difficult from dense molecular cores magnetized to a realistic level, owing to efficient magnetic braking that transports a large fraction of the angular momentum away from the circumstellar region. We review recent progress in the formation and early evolution of disks around young stellar objects of both low-mass and high-mass, with an emphasis on mechanisms that may bridge the gap between observation and theory, including non-ideal MHD effects and asymmetric perturbations in the collapsing core (e.

Thermal Jeans Fragmentation within ~ 1000 AU in OMC-1S.

We present subarcsecond 1.3 mm continuum ALMA observations towards the Orion Molecular Cloud 1 South (OMC-1S) region, down to a spatial resolution of 74 AU, which reveal a total of 31 continuum sources. We also present subarcsecond 7 mm continuum VLA observations of the same region, which allow to further study fragmentation down to a spatial resolution of 40 AU.

Complex Organic Molecules tracing shocks along the outflow cavity in the high-mass protostar IRAS 20126+4104.

We report on subarcsecond observations of complex organic molecules (COMs) in the high-mass protostar IRAS 20126+4104 with the Plateau de Bure Interferometer in its most extended configurations. In addition to the simple molecules SO, HNCO and HCO, we detect emission from CHCN, CHOH, HCOOH, HCOOCH, CHOCH, CHCHCN, CHCOCH, NHCN, and (CHOH). SO and HNCO present a X-shaped morphology consistent with tracing the outflow cavity walls.