AN IMPLICIT LAGRANGIAN CODE FOR THE TREATMENT OF NONSTATIONARY PROBLEMS IN ROTATING ASTROPHYSICAL BODIES

An implicit Lagrangian method based on a triangular grid is developed here for calculations of nonstationary astrophysical processes includi ng collapse of rotating clouds in the first stages of star formation a nd models of supernova explosions in rotating stars. We restrict ourse lves to the development of a reliable hydrodynamical numerical scheme with self-gravitation and use only simple equations of state without t hermal processes, with entropy changing only in the shocks. The qualit y of the method is demonstrated on several test problems. The main app lication of the method is to the collapse of a rapidly rotating gas cl oud. This problem has been investigated by many authors with the same physical conditions. We have obtained results for the stages of the co llapse up to secondary compression and discuss their reliability in co mparison with previous authors. Our results are in qualitative accorda nce with others obtained by Lagrangian methods, while we extending the calculations farther. We do not confirm the formation of a ring struc ture obtained by use of Eulerian schemes.