The Poisson Point Process: an effective tool for radiative transfer
Rainer Wehrse (Zentrum für Astronomie der Universität
Monday 14th January 2008, 12:00
Pratt conference room, 60 Garden Street
In the talk, the Poisson Point Process that is well known in mathematical statistics is introduced and applied to the extinction due to a large number of spectral lines. We address in particular the calculation of the opacity distribution function from the line density, and the distributions of strengths and shapes. When the process is combined with analytical solutions of the radiative transfer equation it allows the very effective calculation of important mean values as, for example, of the radiative flux and acceleration and of the expansion opacity. Examples are shown for plane-parallel media that both absorb and scatter and are static or in differential motion. It is also demonstrated that the process allows easy insight into problems that are nearly impossible to treat numerically, such as the role of the myriad of missing lines in stellar atmosphere models.