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Title: TURBULENCE DECAY AND CLOUD CORE RELAXATION IN MOLECULAR CLOUDS

The turbulent motion within molecular clouds is a key factor controlling star formation. Turbulence supports molecular cloud cores from evolving to gravitational collapse and hence sets a lower bound on the size of molecular cloud cores in which star formation can occur. On the other hand, without a continuous external energy source maintaining the turbulence, such as in molecular clouds, the turbulence decays with an energy dissipation time comparable to the dynamic timescale of clouds, which could change the size limits obtained from Jean's criterion by assuming constant turbulence intensities. Here we adopt scaling relations of physical variables in decaying turbulence to analyze its specific effects on the formation of stars. We find that the decay of turbulence provides an additional approach for Jeans' criterion to be achieved, after which gravitational infall governs the motion of the cloud core. This epoch of turbulence decay is defined as cloud core relaxation. The existence of cloud core relaxation provides a more complete understanding of the effect of the competition between turbulence and gravity on the dynamics of molecular cloud cores and star formation.
Authors:
;  [1] ;  [2]
  1. Center for Combustion Energy, Tsinghua University, Beijing 100084 (China)
  2. Max Planck Institute for Dynamics and Self-Organization (MPIDS), D-37077 Göttingen (Germany)
Publication Date:
OSTI Identifier:
22364312
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 799; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; CLOUDS; COMPARATIVE EVALUATIONS; COSMIC GASES; ENERGY LOSSES; GRAVITATIONAL COLLAPSE; HYDRODYNAMICS; RELAXATION; STAR EVOLUTION; STARS; TURBULENCE