Clump mass function at an early stage of molecular cloud evolution – I. A statistical approach

Authors

  • Sava Donkov,

    Corresponding author
    1. Department of Applied Physics, Technical University, 8 Kliment Ohridski Blvd., 1000 Sofia, Bulgaria
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  • Todor V. Veltchev,

    1. Faculty of Physics, University of Sofia, 5 James Bourchier Blvd., 1164 Sofia, Bulgaria
    2. Institute of Theoretical Astrophysics, Zentrum für Astronomie der Universität Heidelberg, Albert-Überle-Str. 2, 69120 Heidelberg, Germany
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  • Ralf S. Klessen

    1. Institute of Theoretical Astrophysics, Zentrum für Astronomie der Universität Heidelberg, Albert-Überle-Str. 2, 69120 Heidelberg, Germany
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E-mail: savadd@tu-sofia.bg

ABSTRACT

We derive the mass function of condensations (clumps) which were formed through a turbulent cascade over a range of spatial scales L≤ 20 pc during early, predominantly turbulent evolution of a molecular cloud. The approach rests upon the assumption of a statistical clump mass–density relationship nmx with a scale dependence of the exponent x obtained from equipartition relations between various forms of energy of clumps. The derived clump mass function (ClMF) could be represented by series of two or three power laws, depending on the chosen equipartition relation, the velocity scaling index and the type of turbulent forcing. The high-mass ClMF exhibits an average slope Γ≃−1, typical for fractal clouds, whereas its intermediate-mass part is shallower or flattened, in agreement with some observational studies.

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