Star formation triggered by non-head-on cloud-cloud collisions, and clouds with pre-collision sub-structure
Abstract
In an earlier paper, we used smoothed particle hydrodynamics (SPH) simulations to explore star formation triggered by head-on collisions between uniform-density 500 M⊙ clouds, and showed that there is a critical collision velocity, vCRIT. At collision velocities below vCRIT, a hub-and-spoke mode operates and delivers a monolithic cluster with a broad mass function, including massive stars (M⋆ ≳ 10 M⊙) formed by competitive accretion. At collision velocities above vCRIT, a spider's-web mode operates and delivers a loose distribution of small sub-clusters with a relatively narrow mass function and no massive stars. Here we show that, if the head-on assumption is relaxed, vCRIT is reduced. However, if the uniform-density assumption is also relaxed, the collision velocity becomes somewhat less critical: a low collision velocity is still needed to produce a global hub-and-spoke system and a monolithic cluster, but, even at high velocities, large cores - capable of supporting competitive accretion and thereby producing massive stars - can be produced. We conclude that cloud-cloud collisions may be a viable mechanism for forming massive stars - and we show that this might even be the major channel for forming massive stars in the Galaxy.
- Publication:
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Monthly Notices of the Royal Astronomical Society
- Pub Date:
- March 2017
- DOI:
- 10.1093/mnras/stw2956
- Bibcode:
- 2017MNRAS.465.3483B
- Keywords:
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- stars: kinematics and dynamics