Cambridge STARS Homepage


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This is the beta version of an update to the website of the Cambridge STARS code. Additional material should be added in the near future. The previous version of the page can be found here.


This is the homepage of the Cambridge Stellar Evolution Code, which we refer to simply as STARS. The code was originally written by Peter Eggleton in the early 1970s and it has subsequently been used, modified and updated by many people, mostly in his academic lineage (i.e. his students, students of his students, etc.). Below, you will find a brief description of the code, links to download it and a link to the documentation. The page can be navigated by the sidebar to the left.


STARS is a stellar evolution code. Though many such codes exist, STARS is distinguished by several features.

Adaptive non-Lagrangian mesh
The structure and composition is calculated on a mesh that is distributed evenly over a mesh-spacing function that redistributes itself automatically during a star's evolution. By choosing this function prudently, the code follows a model smoothly through many phases of stellar evolution with a small mesh. In most circumstances, just 200 points are sufficient.

Simultaneous solution of structure and composition
The structure and composition equations are solved simultaneously in the relaxation algorithm. Thus, the code accurately models phases where the composition changes rapidly and can effect rapid structure changes.

Small code base
The code is compact and, once understood, easily modified to include different physical processes or model other star-like objects. The present version of the code includes about 5000 lines of functional FORTRAN.


Current version

The following tarball contains the minimal material required for the operation of the current version of the code, which includes the modifications by Richard Stancliffe up to about 2007. The tarball contains


If you are using GNU/Linux with gfortran installed, you should be able to extract the tarball, compile the code with make and run it by executing ./run.


If you're using the code, I recommend that you download and consult the documentation (PDF) now. The documentation describes

and more.


The minimal tarball contains enough to run the code but you may want to evolve different initial models. Also, if you want to evolve stars with different metallicity, you will need the relevant opacity tables.

Opacity tables

The gzipped tables are provided below for the given metallicities. Note that these are not archives, just single compressed files. To evolve a model at a given metallicity Z, copy the table to dat/COtables. The tables are labeled by the figures following the decimal point in the metallicity. For example, COtables_z0001 corresponds to Z=0.0001. The default table corresponds to Z=0.02 (z020). Don't forget to change the metallicity in modin and data!

COtables_z000.gz COtables_z001.gz COtables_z010.gz
COtables_z00001.gz COtables_z002.gz COtables_z020.gz
COtables_z00003.gz COtables_z003.gz COtables_z030.gz
COtables_z0001.gz COtables_z004.gz COtables_z040.gz
COtables_z0003.gz COtables_z006.gz COtables_z050.gz

Input models

Homogeneous zero-age main-sequence

The models below have homogeneous composition at the given metallicity Z and hydrogen abundance X=0.7. They have been allowed to contract to a state of thermal equilibrium. Such models are a useful starting point but the evolution usually starts with a small loop in the HR diagram while the star is converting carbon, nitrogen and oxygen into their equilibrium abundances.

The models have 199 meshpoints and are set to run for 99900 steps. This is to guarantee that the evolution is followed until the code breaks down for some reason.

MetallicityMass (solar units)
0.02 0.5 0.6 0.7 0.8 0.9 1.0 3.0 5.0 7.0 9.0


...about the code

Eggleton, P.P. (1971) MNRAS 151, 351
Eggleton, P.P. (1972) MNRAS 156, 361
Eggleton, P.P., Faulkner, J., Flannery, B.P. (1973) A&A 23, 325
Eggleton, P.P. (1973) MNRAS 163, 279
Pols, O., Tout, C.A., Eggleton, P.P., Han, Z. (1995) MNRAS 274, 964

...that use the code


Below is a list of people who, by their own request, are or have been associated with work with or on the STARS code. If they did a PhD at IoA, their year of completion is in square brackets. If you would like to be added to this list, please contact us.

Last updated by Warrick Ball, 21 September 2012.