Vol. 603
In section 6. Interstellar and circumstellar matter

Fragmentation and disk formation in high-mass star formation: The ALMA view of G351.77-0.54 at 0.06'' resolution

Understanding the fragmentation of high-mass gas clumps and the subsequent formation and evolution of accretion disks around young high-mass protostars remains an unsolved question in high-mass star formation research. In this paper, the authors report ALMA observationsof the massive hot core region G351.77-0.54 with baselines up to 1.5 km, leading to at an unprecedented spatial resolution of 0.06 arcsec (130 AU) at a source distance of 2.2 kpc. Within the inner few 1000 AU, G351.77 fragments into at least four cores (see figure). The kinematics of the central structure (#1) reveal contributions from a rotating disk, an infalling envelope and potentially also an outflow, whereas the spectral profile toward source #2 can be attributed to infall, with a rate of upto 10ˆ-4 - 10ˆ-3 solar mass per year. A stability analysis of the rotating central structure suggests that it is axisymmetrically stable.However, asymmetric instabilities such as spiral arms may still occur on smaller, so far unresolved, spatial scales.