Fragmentation of Molecular Clouds: The Initial Phase of a Stellar Cluster

The isothermal gravitational collapse and fragmentation of a region within a molecular cloud and the subsequent formation of a protostellar cluster are investigated numerically. The clump mass spectrum that forms during the fragmentation phase can be well approximated by a power-law distribution dN/dM∝M−1.5. In contrast, the mass spectrum of protostellar cores that form in the centers of Jeans-unstable clumps and that evolve through accretion and N-body interactions is described by a lognormal distribution with a width that is in excellent agreement with observations of multiple stellar systems.

[1]  I. Bonnell,et al.  Fragmentation of elongated cylindrical clouds. VI: Comparison with observations , 1993 .

[2]  W. Benz.  Smooth Particle Hydrodynamics: A Review , 1990 .

[3]  Y. Nakajima,et al.  Formation and Evolution of Filamentary Molecular Clouds with Oblique Magnetic Field , 1996 .

[4]  P. Podsiadlowski,et al.  Dynamical interactions between young stellar objects and a collisional model for the origin of the stellar mass spectrum , 1995 .

[5]  M. Bate,et al.  Resolution requirements for smoothed particle hydrodynamics calculations with self-gravity , 1997 .

[6]  Gravitational fragmentation - A comparison with W49A , 1991 .

[7]  P. Bodenheimer,et al.  PROTOSTELLAR FRAGMENTATION IN A POWER-LAW DENSITY DISTRIBUTION , 1997, astro-ph/9706092.

[8]  Toshikazu Ebisuzaki,et al.  A special-purpose computer for gravitational many-body problems , 1990, Nature.

[9]  R. Larson.  Calculations of three-dimensional collapse and fragmentation , 1978 .

[10]  A. Boss.  Collapse and Fragmentation of Molecular Cloud Cores. V. Loss of Magnetic Field Support , 1997 .

[11]  E. Salpeter.  The Luminosity function and stellar evolution , 1955 .

[12]  I. A. Bonnell,et al.  Modelling accretion in protobinary systems , 1995 .

[13]  J. Monaghan,et al.  Shock simulation by the particle method SPH , 1983 .

[14]  H. Zinnecker.  Star formation from hierarchical cloud fragmentation - A statistical theory of the log-normal Initial Mass Function , 1984 .

[15]  J. Stutzki,et al.  High spatial resolution isotopic CO and CS observations of M17 SW - The clumpy structure of the molecular cloud core , 1989 .

[16]  A. Boss,et al.  Protostars and Planets VI , 2000 .

[17]  J. Monaghan.  Smoothed particle hydrodynamics , 2005 .

[18]  Christopher A. Tout,et al.  The low-luminosity stellar mass function , 1990 .

[19]  P. P. Ewald.  Die Berechnung optischer und elektrostatischer Gitterpotentiale , 1921 .

[20]  C. Clarke,et al.  Accretion and the stellar mass spectrum in small clusters , 1997 .

[21]  S. J. Chapman,et al.  Binary star formation: accretion-induced rotational fragmentation , 1995 .

[22]  A. Whitworth,et al.  Binary star formation: gravitational fragmentation followed by capture , 1995 .

[23]  Leo Blitz,et al.  DETERMINING STRUCTURE IN MOLECULAR CLOUDS , 1994 .

[24]  J. Robert Buchler,et al.  The Numerical Modelling of Nonlinear Stellar Pulsations , 1990 .

[25]  Bruce G. Elmegreen,et al.  The Initial Stellar Mass Function from Random Sampling in a Turbulent Fractal Cloud , 1997 .

[26]  Ralf Klessen.  GRAPESPH with fully periodic boundary conditions: fragmentation of molecular clouds , 1997 .

[27]  A Theory of the IMF for Star Formation in Molecular Clouds , 1996, astro-ph/9601139.

[28]  G. Gilmore,et al.  The distribution of low-mass stars in the Galactic disc , 1993 .

[29]  J. Monaghan,et al.  A simulation of the collapse and fragmentation of cooling molecular clouds , 1991 .

[30]  A. Whitworth,et al.  Self-similar condensation of spherically symmetric self-gravitating isothermal gas clouds , 1985 .

[31]  D. Lin,et al.  Coalescence, Star Formation, and the Cluster Initial Mass Function , 1996 .

[32]  Matthias Steinmetz.  Grapesph: cosmological smoothed particle hydrodynamics simulations with the special-purpose hardware GRAPE , 1996 .

[33]  M. Skrutskie,et al.  in Protostars and Planets III , 1993 .

[34]  P. Bodenheimer,et al.  FRAGMENTATION IN A CENTRALLY CONDENSED PROTOSTAR , 1995, astro-ph/9510011.