Amelia Stutz

Universidad de Concepcion

Cluster formation and gas kinematics in high mass clouds.

By observationally scrutinizing the nearest high mass clouds and

protoclusters, we gain new insights into cluster formation physics.

The Integral Shaped Filament (ISF) is home to the nearest significant

protocluster, the Orion Nebula Cluster (ONC/M42).  Based on a high

density of observables of both the gas and stars, we previously

proposed the "slingshot" mechanism, requiring that the gas ISF

oscillate ejecting stars. The B-field morphology (possibly helical)

and strength, compared with the gas mass distribution, indicates that

magnetic instabilities may be propagating through the cloud driving

the oscillations in the ISF. These may be responsible for the

slingshot.  The gas kinematics exhibit twisting and turning features

that may be consistent with rotation and helical structures in the

dense gas.  We show that the stellar density follows a Plummer profile

while the gas follows a cylindrical power law.  The stellar

contribution to the gravitational field is nearly equal to that of the

gas at r=a.  At all other radii the field is gas-dominated.  The

cluster crossing time is ~ 0.5 Myr, nearly identical to the filament

oscillation timescale.  These results reveal an intimate connection

between the stars and the gas, such that tidal effects due to filament

oscillations may set the protocluster structure.  That is, the gas

density regulates the star density in the ONC. Meanwhile, in

California cloud, which has the same mass as Orion but is at an

earlier evolutionary stage (~1/10th the protostars), we detect

rotation in cluster-forming filament L1482.  Results in extragalactic

systems show that cloud rotation is set by the overall galaxy rotation

and not consistent with e.g. cloud-collision models. Combined, these

results may indicate that velocity gradients in Milky Way

protoclusters are naturally explained by rotation (and helicity),

which is established on large scales of galaxy disks and then

percolates down to protocluster and possibly even to the tiny scales

of protostars.