THE KINEMATICS OF MOLECULAR CLOUD CORES IN THE PRESENCE OF DRIVEN AND DECAYING TURBULENCE: COMPARISONS WITH OBSERVATIONS

2007/12/31 by Stella S. R. Offner, S. S. R. Offner, M. R. Krumholz +5 · 51 citations
Physics and Astronomy · #Astro and Planetary Science #Astrophysics #Astrophysics and Star Formation Studies #Classical mechanics #Computational physics #Core (optical fiber) #Galaxy #Kinematics #Line (geometry) #Mechanics #Meteorology #Molecular cloud #Ophiuchus #Optics #Physics #Star formation #Stars #Stellar, planetary, and galactic studies #Supersonic speed #Thermal #Turbulence #Velocity dispersion #astro-ph

paper · pdf · doi:10.1088/0004-6256/136/1/404

published in The Astronomical Journal 136(1), 404-420 (Institute of Physics) · 18 pages, 12 figures, accepted to AJ

openalex publication_date 2008/06/13 · arxiv created 2008/07/01 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/06

Abstract

In this study, we investigate the formation and properties of prestellar and protostellar cores using hydrodynamic self-gravitating adaptive mesh refinement simulations, comparing the cases where turbulence is continually driven and where it is allowed to decay. We model observations of these cores in the C 18 O(2 → 1), NH 3 (1, 1), and N 2 H + (1 → 0) lines, and from the simulated observations we measure the line widths of individual cores, the line widths of the surrounding gas, and the motions of the cores relative to one another. Some of these distributions are significantly different in the driven and decaying runs, making them potential diagnostics for determining whether the turbulence in observed star-forming clouds is driven or decaying. Comparing our simulations with observed cores in the Perseus and ρ Ophiuchus clouds shows reasonably good agreement between the observed and simulated core-to-core velocity dispersions for both the driven and decaying cases. However, we find that the line widths through protostellar cores in both simulations are too large compared to the observations. The disagreement is noticeably worse for the decaying simulation, in which cores show highly supersonic infall signatures in their centers that decrease toward their edges, a pattern not seen in the observed regions. This result gives some support to the use of driven turbulence for modeling regions of star formation, but reaching a firm conclusion on the relative merits of driven or decaying turbulence will require more complete data on a larger sample of clouds as well as simulations that include magnetic fields, outflows, and thermal feedback from the protostars.

Citations

• Radiation‐Hydrodynamic Simulations of Collapse and Fragmentation in Massive Protostellar Cores
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Cited by

• The astrochemical evolution of turbulent giant molecular clouds: physical processes and method of solution for hydrodynamic, embedded starless clouds