2003/06/09 by Charles F. Gammie, C. F. Gammie, Yen‐Ting Lin +5 · 5 citations
Earth and Planetary Sciences · Physics and Astronomy · #Angular momentum #Astrophysics #Astrophysics and Star Formation Studies #Atmospheric Ozone and Climate #Classical mechanics #Geometry #Mechanics #Molecular cloud #Physics #Rotation (mathematics) #Scaling #Star formation #Stars #Stellar, planetary, and galactic studies #Turbulence #astro-ph
paper · pdf · doi:10.1086/375635
published as Astrophys.J. 592 (2003) 203-216 · 14 pages, 13 figures, to appear in 2003 July 20 ApJ
arxiv created 2003/06/09 · openalex publication_date 2003/07/18 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Observations reveal concentrations of molecular line emission on the sky, called "clumps," in dense, star-forming molecular clouds. These clumps are believed to be the eventual sites of star formation. We study the three-dimensional analogs of clumps using a set of self-consistent, time-dependent numerical models of molecular clouds. The models follow the decay of initially supersonic turbulence in an isothermal, self-gravitating, magnetized fluid. We find the following. (1) Clumps are intrinsically triaxial. This explains the observed deficit of clumps with a projected axis ratio near unity, and the apparent prolateness of clumps. (2) Simulated clump axes are not strongly aligned with the mean magnetic field within clumps nor with the large-scale mean fields. This is in agreement with observations. (3) The clump mass spectrum has a high-mass slope that is consistent with the Salpeter value. There is a low-mass break in the slope at ~0.5 M ☉ , although this may depend on model parameters including numerical resolution. (4) The typical specific spin angular momentum of clumps is 4 × 10 22 cm 2 s -1 . This is larger than the median specific angular momentum of binary stars. Scaling arguments suggest that higher resolution simulations may soon be able to resolve the scales at which the angular momentum of binary stars is determined.