TURBULENCE DECAY AND CLOUD CORE RELAXATION IN MOLECULAR CLOUDS

Journal Article · Sun Feb 01 04:00:00 EST 2015 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/799/2/227· OSTI ID:22364312

Gao, Yang; Law, Chung K. ^[1]; Xu, Haitao ^[2]

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1. Center for Combustion Energy, Tsinghua University, Beijing 100084 (China)
2. Max Planck Institute for Dynamics and Self-Organization (MPIDS), D-37077 Göttingen (Germany)

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.

• OSTI ID: 22364312
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 799; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
CLOUDS
COMPARATIVE EVALUATIONS
COSMIC GASES
ENERGY LOSSES
GRAVITATIONAL COLLAPSE
HYDRODYNAMICS
RELAXATION
STAR EVOLUTION
STARS
TURBULENCE