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| EPoS Contribution |
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Anchoring Magnetic Field in Turbulent Molecular Clouds
Hua-bai Li Max-Planck Institut für Astronomie, Heidelberg, Germany | |
| One of the key problems in star formation research is to determine the role of magnetic fields. Because of the sensitivities of current instruments, our knowledge of cloud magnetic fields has been mostly concentrated on cloud cores, using e.g. field morphologies, Chandrasekhar-Fermi method and Zeeman measurements. Knowing field strength from cloud cores, however, tells us nothing about the global property of a cloud because both super- and sub-Alfvenic cores can possibly develop from either super- or sub-Alfvenic clouds. Nevertheless, global field strength of a cloud are crucial initial conditions which can significantly influence the efficiency and rate of star formation. We compared magnetic field directions in high-density, small-scale cores (pc to sub-pc scale) with those in the low-density, large-scale inter cloud media (several hundred pc scale), and saw a significant correlation. Comparing with simulations, a globally super-Alfvenic cloud does not fit into this picture. | |
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| Caption: The background image shows the far-infrared map in representative color and logarithmic scale. Superposed on it are the magnetic field directions inferred from optical polarimetry data (blue lines) tracing the diffused regions. The average of all the optical data is shown as the thick gray line. Magnetic fields within eight high-density cloud cores (labels A through H on the background map) are mapped using submillimeter polarimetry and the results are shown as insets, using red lines on individual representative-color intensity maps. The average direction of each core is shown as a white line superposed on the core map; these white lines also are plotted on the background map. Even though the core separations exceed the core sizes by as much as a factor of 100, they are for the most part "magnetically connected", i.e. the cores' average field directions are similar. Moreover, these directions are close to the average field direction seen in the diffused regions. | |
| Collaborators: C.D. Dowell, JPL/Caltech, USA A. Goodman, CfA, USA R. Hildebrand, U. of Chicago, USA G. Novak, Northwestern U., USA |
Key publication
Suggested Session: Magnetic Fields, Molecular Clouds, Turbulence |