Magnetic fields and the location of the PDR
| dc.creator | Ferland, Gary J. | |
| dc.date | 2008-11-12 | |
| dc.date.accessioned | 2026-07-07T12:15:59Z | |
| dc.date.available | 2026-07-07T12:15:59Z | |
| dc.description | I review recent studies of the emission-line regions in Orion and M17. Both have similar geometries, a bubble of hot shocked gas surrounding the central star cluster, with H^+, H^0, and H_2 regions, often referred to as H II regions, PDRs, and molecular clouds, forming successive shells on the surface of a molecular cloud. The magnetic fields in the H^0 regions have been measured with 21 cm Zeeman polarization and are found to be 1 -- 2 dex stronger than the field in the diffuse ISM. The regions appear to be in rough hydrostatic equilibrium. The H^+ region is pushed away from the star cluster by starlight radiation pressure. Since most starlight is in ionizing radiation, most of its outward push will act on the H^+ region and then on to the H^0 region. The magnetic pressure in the H^0 region balances the momentum in starlight and together they set the location of the H^0 region. The picture is that, when the star cluster formed, it created a bubble of ionized gas which expanded and compressing surrounding H^0 and H_2 regions. The magnetic field was amplified until its pressure was able to support the momentum in starlight. This offers a great simplification in understanding the underlying physics that establishes parameters for PDR models. | |
| dc.identifier | https://arxiv.org/abs/0811.2007 | |
| dc.identifier | http://arxiv.org/abs/0811.2007 | |
| dc.identifier | EASPubl.Ser.31:53-56,2008 | |
| dc.identifier | doi:10.1051/eas:0831011 | |
| dc.identifier.uri | http://salesiana.dossiersoluciones.com/handle/123456789/211662 | |
| dc.subject | Astrophysics | |
| dc.title | Magnetic fields and the location of the PDR | |
| dc.type | text |