Effects of Magnetic Field and Far-ultraviolet Radiation on the Structures of Bright-rimmed Clouds
Abstract
The bright-rimmed cloud SFO 22 was observed with the 45 m telescope of Nobeyama Radio Observatory in the 12CO (J = 1-0), 13CO (J = 1-0), and C18O (J = 1-0) lines, where well-developed head-tail structure and small line widths were found. Such features were predicted by radiation-driven implosion models, suggesting that SFO 22 may be in a quasi-stationary equilibrium state. We compare the observed properties with those from numerical models of a photoevaporating cloud, which include effects of magnetic pressure and heating due to strong far-ultraviolet (FUV) radiation from an exciting star. The magnetic pressure may play a more important role in the density structures of bright-rimmed clouds than the thermal pressure that is enhanced by the FUV radiation. The FUV radiation can heat the cloud surface to near 30 K however, its effect is not enough to reproduce the observed density structure of SFO 22. An initial magnetic field of 5 μG in our numerical models produces the best agreement with the observations, and its direction can affect the structures of bright-rimmed clouds.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- March 2013
- DOI:
- 10.1088/0004-637X/766/1/50
- arXiv:
- arXiv:1301.3610
- Bibcode:
- 2013ApJ...766...50M
- Keywords:
-
- ISM: clouds;
- ISM: individual objects: SFO22;
- ISM: magnetic fields;
- methods: numerical;
- methods: observational;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- 14 pages, 13 figures, accepted for publication in ApJ