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.

Dynamics of cluster-forming hub-filament systems: The case of the high-mass star-forming complex Monoceros R2.

Context: High-mass stars and star clusters commonly form within hub-filament systems. Monoceros R2 (hereafter Mon R2), at a distance of 830 pc, harbors one of the closest such systems, making it an excellent target for case studies.

Aims: We investigate the morphology, stability and dynamical properties of the Mon R2 hub-filament system.

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.

Far-infrared observations of a massive cluster forming in the Monoceros R2 filament hub.

We present far-infrared observations of Monoceros R2 (a giant molecular cloud at approximately 830 pc distance, containing several sites of active star formation), as observed at 70 m, 160 m, 250 m, 350 m, and 500 m by the Photodetector Array Camera and Spectrometer (PACS) and Spectral and Photometric Imaging Receiver (SPIRE) instruments on the Space Observatory as part of the imaging survey of OB young stellar objects (HOBYS) Key programme. The data are complemented by SCUBA-2 data in the submillimetre range, and WISE and data in the mid-infrared. In addition, CO data from the IRAM 30-m Telescope are presented, and used for kinematic information.