Logo for the MESA stellar evolution code

This page hosts MESA-Web, a web-based interface to a state-of-the-art stellar evolution code.

Background to MESA-Web

The standard computational tool of anyone interested in understanding stars is a stellar evolution code — a piece of software that can construct a model for the interior of a star, and then evolve it over time. Evolution codes allow us to check and refine the various physical theories that together compose stellar astrophysics (e.g., atomic physics, nuclear physics, fluid dynamics, thermodynamics); they provide laboratories for performing experiments on stars (e..g, discovering what factors contribute to the formation of red giants); and, they shed light on stages of stellar evolution that may be too fleeting to observe directly in the Universe.

Stellar evolution codes are often complicated to use, and so many years ago I created EZ-Web, a simple, web-based interface to Bill Paxton's Evolve ZAMS code. More recently, Carl Fields and Frank Timmes (Arizona State University) created a similar tool, MESA-Web, based on the fully-featured MESA code (Bill Paxton again, with the help of a development team).

This incarnation of MESA-Web is a re-implementation of the original ASU service that supports greater computational capacity, plus a number of other improvements. We've striven to keep the functionality the same, but the look and feel is slightly different (to fit in with the unintentionally retro aesthetic of Mad Star).

Using MESA-Web

To use MESA-Web, visit the calculation submission page and follow the instructions at the top. To learn how to customize input parameters, see the MESA-Web Input page; and to understand the outputs produced by a completed calculation, see the MESA-Web Output page.

Frequently Asked Questions (FAQ)

Q: Whom do I contact for assistance with MESA-Web?

A: You can contact the MESA-Web team at

Q: How do I cite MESA-Web?

A: The bibliographic entry should appear as: Fields, C. E., Timmes, F. X., & Townsend R. H. D. (2015-). MESA-Web. Retrieved from

Q: Can I modify more than a single nuclear reaction rate?

A: Unfortunately, no; to do that, you should consider installing and using MESA instead of MESA-Web.

Learn more about MESA

The Modules for Experiments in Stellar Astrophysics (MESA) code at the heart of the MESA-Web tool provides a modern software infrastructure for sustained innovation in the stellar astrophysics community. MESA solves the 1D fully coupled structure and composition equations governing stellar evolution with an implicit finite volume scheme. State-of-the-art modules provide adaptive mesh refinement, sophisticated timestep controls, non-adiabatic oscillation capabilities, equation of state, opacity, nuclear reaction rates, element diffusion, boundary conditions, and changes to the mass of the star.

To learn more about MESA, see the instrument papers describing the software's design and demonstrating its capabilities:

Updated 2021-09-07 21:14:08