Turbulence and star formation in molecular clouds
R. B. Larson;
MNRAS, 1981, 194, 809
ABSTRACT:Consideration is given to the turbulence properties of molecular clouds and their implications for star formation.
Data for 54
molecular clouds and condensations is presented which reveals cloud velocity
dispersion and region size to follow a power-law relation, similar to the
Kolmogoroff law for subsonic turbulence.
Examination of the dynamics of the
molecular clouds for which mass determinations are available reveals
essentially all of them to be gravitationally bound, and to approximately satisfy
the virial theorem.
The observation of moderate scatter in the
dispersion-size relation is noted to imply that most regions have not collapsed much
since formation, suggesting that processes of turbulent hydrodynamics
have played an important role in producing the observed substructures.
A
lower limit to the size of subcondensations at which their internal motions
are no longer supersonic is shown to predict a minimum protostellar mass on
the order of a few tenths of a solar mass, while massive protostellar clumps
are found to develop complex internal structures, probably leading to the
formation of prestellar condensation nuclei.
The observed turbulence of
molecular clouds is noted to imply lifetimes of less than 10 million years.
KEYWORDS: interstellar matter, molecular clouds, protostars, star formation, turbulence effects, clumps, density distribution, stellar gravitation, stellar mass, velocity distribution, virial theorem
PERSOKEY:turbulence, ,
CODE: larson81