Do cloud-cloud collisions trigger high-mass star formation? I. Small cloud collisions

TL;DR

This study uses high-resolution simulations to explore how cloud-cloud collisions influence high-mass star formation, revealing that faster collisions produce more cores and that core mass distribution aligns with observations.

Contribution

It provides new insights into the role of collision velocity and turbulence in core formation and growth, supported by detailed simulations matching observed core mass distributions.

Findings

Faster collision velocities increase core numbers.

Core mass distribution follows a power law with index -1.6.

Shock fronts are key sites for core growth and formation.

Abstract

We performed sub-parsec (~0.06pc) scale simulations of two idealised molecular clouds with different masses undergoing a collision. Gas clumps with density greater than 1e-20 g/cm3 (0.3e4 cm-3) were identified as pre-stellar cores and tracked through the simulation. The colliding system showed a partial gas arc morphology with core formation in the oblique shock-front at the collision interface. These characteristics support NANTEN observations of objects suspected to be colliding giant molecular clouds (GMCs). We investigated the effect of turbulence and collision speed on the resulting core population and compared the cumulative mass distribution to cores in observed GMCs. Our results suggest that a faster relative velocity increases the number of cores formed but that cores grow via accretion predominately while in the shock front, leading to a slower shock being more important for core growth. The core masses obey a power law relation with index gamma = -1.6, in good agreement with observations. This suggests that core production through collisions should follow a similar mass distribution as quiescent formation, albeit at a higher mass range. If cores can be supported against collapse during their growth, the estimated ram pressure from gas infall is of the right order to counter the radiation pressure and form a star of 100Msun.