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Full-Text Articles in Physics
Infrared Emission And Dynamics Of Outlfows In Late-Type Stars, Željko Ivezić, Moshe Elitzur
Infrared Emission And Dynamics Of Outlfows In Late-Type Stars, Željko Ivezić, Moshe Elitzur
Physics and Astronomy Faculty Publications
The dynamical structure and infrared emission of winds around late-type stars are studied in a self-consistent model that couples the equations of motion and radiative transfer. Thanks to its scaling properties, both the dynamics and IR spectrum of the solution are fully characterized by τF, the flux-averaged optical depth of the wind. Five types of dust grains are considered: astronomical silicate, crystalline olivine, graphite, amorphous carbon and SiC, as well as mixtures. Analysis of infrared signatures provides constraints on the grain chemical composition and indications for the simultaneous existence of silicate and carbon grains. The abundances of crystalline …
Radiation Pressure And Emission Clouds Around Active Galactic Nuclei, Moshe Elitzur, Gary J. Ferland
Radiation Pressure And Emission Clouds Around Active Galactic Nuclei, Moshe Elitzur, Gary J. Ferland
Physics and Astronomy Faculty Publications
Detailed calculations of the contribution of the trapped line photons to the overall pressure in line-emitting regions around active galactic nuclei are presented. They lead to the conclusion that radiation pressure is a significant factor in determining the stability of these clouds.
Radiation Pressure And The Stability Of Broad-Line Region Clouds, Gary J. Ferland, Moshe Elitzur
Radiation Pressure And The Stability Of Broad-Line Region Clouds, Gary J. Ferland, Moshe Elitzur
Physics and Astronomy Faculty Publications
We discuss two constraints on the existence and stability of quasar emission-line gas. The case of a constant pressure photoionized cloud in pressure equilibrium with a surrounding hot gas is considered. We show that the radiation pressure of the internally generated line emission makes a significant contribution to the total pressure in standard broad-line region models, and that models with either a higher ionization parameter or lower gas density are dominated by radiation pressure and hence unstable. Further, clouds with ionization parameters lower than the standard value cannot be supported by any hot gas which is heated only by the …