S E M I N A R IDepartament d'Astronomia i Astrofísica
Universitat de València
Unsteady spherical accretion of gas on to a solid body
Instituto de Matemáticas y Física Fundamental, CSIC, Madrid
Seminari del departament d'Astronomia i Astrofísica
Dimecres 19 novembre 2003
The process of downfall of initially homogeneous gas onto a solid ball due to the ball's gravity (relevant in astrophysical situations) is studied with a combination of analytic and numerical methods. The initial explicit solution soon becomes discontinuous and gives rise to a shock wave. Afterwards, there is a crossover between two intermediate asymptotic similarity regimes, where the shock wave propagates outwards according to two self-similar laws, initially accelerating and eventually decelerating and vanishing, leading to a static state. The numerical study allows one to investigate in detail this dynamical problem and its time evolution, verifying and complementing the analytic results on the initial solution, intermediate self-similar laws and static long-term solution.