Clumpy shocks and the clump mass function

Abstract

In this paper, we examine whether clumpy, colliding, flows could be responsible for the clump mass functions that have been observed in several regions of embedded star formation, which have been shown to be described by a Salpeter type slope. The flows presented here, which comprise a population of initially identical clumps and the calculations are performed with and without the inclusion of self-gravity. When the shock region is at its densest, we find that the clump mass spectrum is always well modelled by a Salpeter type slope. This is true regardless of whether the self-gravity is included in the simulations or not. In the non-self-gravitating simulations, this slope is retained at lower Mach numbers (Mach 5 and 10) as the simulations progress past the densest phase. In the simulations which include self-gravity, we find that low Mach number runs yield a flatter mass function after the densest phase. This is simply a result of increased coagulation due to gravitational collapse of the flows. In the high Mach number runs (Mach 20) the Salpeter slope is always lost. The self gravitating calculations also show that the sub-group of gravitationally bound clumps in which star formation occurs, always contain the most massive clumps in the population. The mass function of these bound star forming clumps is not at all similar to the Salpeter type mass function observed for stars in the field. We conclude that the clump mass function may not only have nothing to do with gravity, but also nothing to do with the star formation process and the resulting mass distribution of stars. This raises doubt over the claims that the clump mass function is the origin of the stellar IMF, for regions such as rho Oph, Serpens and the Orion B cloud.

Accepted for publication in MNRAS. 10 pages, 4 figures and 1 table

References in corpus (12)

• The Stellar IMF from Turbulent Fragmentation
• Modelling Accretion in Protobinary Systems
• The Formation of a Star Cluster: Predicting the Properties of Stars and Brown Dwarfs
• Star Formation in a Crossing Time
• Star formation in clusters: a survey of compact mm-wave sources in the Serpens core
• The Formation of Stellar Clusters: Gaussian Cloud Conditions I
• The Formation of Stellar Clusters: Mass Spectra from Turbulent Molecular Cloud Fragmentation
• The Formation of Molecular Clouds
• Spiral shocks, triggering of star formation and the velocity dispersion in Giant Molecular Clouds
• The Mass Spectra of Cores in Turbulent Molecular Clouds and Implications for the Initial Mass Function
• Dynamically triggered star formation in giant molecular clouds
• Hydrodynamical simulations of a cloud of interacting gas fragments

Cited by in corpus (17)

• Limiting Accretion onto Massive Stars by Fragmentation-Induced Starvation
• Clump Lifetimes and the Initial Mass Function
• Simulations of spiral galaxies with an active potential: molecular cloud formation and gas dynamics
• On the formation of very metal-poor stars: The case of SDSS J1029151+172927
• The IMF of stellar clusters: effects of accretion and feedback
• High Mass Star Formation. III. The Functional Form of the Submillimeter Clump Mass Function
• Massive Clumps in the NGC 6334 Star Forming Region
• Star Formation in Molecular Clouds
• Clumpy and fractal shocks, and the generation of a velocity dispersion in molecular clouds
• The role of low-mass star clusters in massive star formation. The Orion Case
• Are turbulent spheres suitable initial conditions for star-forming clouds?
• Mass Functions in Fractal Clouds: The Role of Cloud Structure in the Stellar Initial Mass Function
• X-ray embedded stars as driving sources of outflow-driven turbulence in OMC1-S
• The role of previous generations of stars in triggering star formation and driving gas dynamics
• Astrophysics in 2006
• Spiral arm triggering of star formation
• Formation of accretion centers in simulations of colliding uniform density H${}_2$ cores