The Athena Code

What is it?

Athena is a grid-based code for astrophysical gas dynamics, based on higher-order Godunov methods, with nested and adaptive mesh capabilities. The original development efforts were supported by the NSF Information Technology Research (ITR) program. As part of the project, Athena will be made freely available to the astrophysics community, along with complete documentation and web-based training material.

The current version of the code (v3.1) implements algorithms for:

• compressible hydrodynamics and ideal MHD in one-, two-, or three-spatial dimensions,
• ideal gas equation of state with arbitrary &gamma (including &gamma = 1, an isothermal EOS).
• first-, second- or third-order characteristic interpolation in the primitive variables,
• numerical fluxes computed using a variety of approximate and/or linearized Riemann solvers,
• source terms due to a static gravitational potential,
• self-gravity computed using FFTs,
• an arbitrary number of passive scalars advected with the flow,
• parallelization using domain decomposition with MPI.

Who, where, when, and why?

The code is being developed by Jim Stone (Princeton University), Tom Gardiner (Cray Research), Peter Teuben (University of Maryland),, and John Hawley (University of Virginia). Code development began in 2000, and is on-going.

The primary motivations for developing Athena are to (1) adapt higher-order Godunov schemes for astrophysical MHD, (2) use a single-step Eulerian update so the solver can be used with adaptive mesh refinement, (3) optimize and parallelize the implementation on modern, distributed memory processors, and (4) distribute the code to the astrophysics community with documentation and web-based training tools. The first three motivations are driven by our own research needs, the last is done in the hope the community will find the resulting code useful for their own research.

Code Tests

Find out more about the test problems that have been most helpful in developing Athena with the following link.

The lastest additions to the Test Suite include several 3D problems. Also see the Athena3D in Fortran webpage for even more tests and results.

Applications

Follow the link below to see some of the latest applications that have used Athena.

Astrophysical Applications using Athena

Download the source code and documentation

There are now multiple versions of the C code available, and a version of the 3D code in Fortran 95. You may use the code freely as is, modify it for your own applications, or use it as a template for your own code.

Athena1.1: One-Dimensional Version in C

The first version athena1.0 was made public in February, 2003. The next version athena1.1 corrected errors in the isothermal eigensystems, and assorted bugs. The functionality of both versions was fairly limited: in particular, they solve the equations of motion in one-dimension only. Neither version is available for downloading: use the latest version athena3.1 instead.

Athena2.0: Two-Dimensional Version in C

A two-dimensional version was made public in December, 2004. Documentation included a User's Guide, Programmer's Guide, and technical papers on the algorithm implemented in multi-dimensions (we developed a new unsplit MHD algorithm based on Constrained Transport). This version of the code is no longer available for download; use the latest version athena3.1 instead.

Athena3.1: Three-Dimensional Version in C, v3.1

athena3.1 download page

Athena3D in Fortran

Documentation