Astronomy and Astrophysics, volume 329, 249-264 (1998/1-1)
Clump mass spectra of molecular clouds.
KRAMER C., STUTZKI J., ROEHRIG R. and CORNELIUSSEN U.
Abstract (from CDS):
We present clump mass spectra of the seven molecular clouds L1457, MCLD 126.6+24.5, NGC 1499SW, Orion B South, S140, M17SW, and NGC 7538, which were derived by a Gaussian clump decomposition algorithm from large scale isotopomeric CO maps. We discuss in detail the reliability of the mass spectra derived by studying their dependence on the control parameters of the decomposition algorithm. All clump mass spectra found are consistent with a power law, dN/dM∝M–α, with α between 1.6 and 1.8. Due to the different resolution of the observations and the different distances of the clouds, the clump masses range from several 104M☉ in NGC 7538 down to 10–4M☉, less than the mass of Jupiter, in the nearby cloud L1457. The large dynamic range covered by the observations is reflected by the high number of clumps found in each cloud, which lie between 100 and 1300. The spectral index of the clump mass distributions thus is independent of the wide range of physical properties of the clouds studied. In particular, there are no indications of a turnover of the clump mass power law index at a characteristic clump mass such as the Jeans mass, below which the clumps become gravitationally unbound. This is particularly emphasized by the clump properties in L1457 most of which are clearly substellar and which are far from being gravitationally bound objects.
interstellar medium: clouds - structure - molecules
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