Smart: A program to automatically compute accelerations and variational equations

Abstract

Modern astronomical potentials modeling galaxies or stellar systems can be rather involved, and deriving their first derivatives (accelerations) and second derivatives (variational equations) in order to compute orbits and their chaoticity may be a formidable task. We present here a fully automated routine, dubbed Smart, with which the accelerations and the variational equations of an arbitrary potential that has been written in the Fortran 77 language can be computed. Almost any Fortran 77 statement is admitted in the potential, and the output are standard Fortran 77 routines ready to use. We validate our algorithm with a set of potentials including time-dependent, velocity-dependent and very complex potentials that even involve auxiliary routines. We also describe with some detail a realistic seven-component Galactic potential, MilkyWayHydra, which yields very involved derivatives, thus being a good test bed for Smart.

37 pages, 5 figures. To be published in Astronomy and Computing, in press

References in corpus (4)

• The Auriga Project: the properties and formation mechanisms of disc galaxies across cosmic time
• The fine-grained phase-space structure of Cold Dark Matter halos
• A comparison of different indicators of chaos based on the deviation vectors. Application to symplectic mappings
• Chaos detection tools: application to a self-consistent triaxial model