Dartmouth Stellar Evolution Web Server

Dartmouth's stellar evolution web server provides a Java applet which allows the user to calculate models for the evolution of stars. The user may view the results of the calculations graphically and/or access the calculated data files directly. The output includes a file giving the global properties of the evolution run (age, luminosity, effective temperature, etc) along with a file which provides detailed structural information for each model in the evolutionary sequence. The applet is restricted to calculating stellar models which are in the mass range of 0.5 to 5 solar masses. The calculation starts on the zero-age main sequence (start of hydrogen fusion) and may be terminated at any point in the evolution up to the start of core helium fusion.

The calculation of the stellar evolution models requires a large number of computations, requiring a fast computer for a reasonable turn-around time. The calculations of the stellar evolution models is performed on our web server (currently an 8 processor Athlon 1900 cluster), and typically require from one to ten minutes to complete.

To use the Java applet, you must enable Java in your browser. We have successfully used this applet with Firefox, Safari and Internet Explorer on computers running Windows, Linux and Mac OS X.

In order to use the applet you must log in every time you access the applet. If you are a new user you must create a new user identification before you log in to the applet. Once you log in to the applet, you may perform the following actions using the tab panes at the top of the applet:

Start Run pane: start a new stellar evolution model run; results will open in a new browser window unless you request that the URL be e-mailed to you
View Run pane: view the results (either graphically, or as plain text files) of previous calculations.
Delete Run pane: delete the results of previous calculations that you specify
Help pane: Provides details on the meaning and allowed range of parameters used to start a run.

There are two versions of the applet. The standard version is appropriate for most user. Click HERE to run the standard version of the applet. The advanced version of the applet allows the user to change how convection and diffusion are treated by the code. Click HERE for the advanced version of the applet.

The stellar model calculations are performed by a specialized version of the computer code Brian Chaboyer uses in his research. Details of this code may be found in the following publications: Chaboyer et al. 2001, ApJ, 562, 521 and Guenther et al. 1992, ApJ, 387, 372. If you use the results of these stellar evolution calculations in any publication, please reference the above two papers along with the URL of this web page.

In order to allow for the automatic generation of stellar evolution models for a wide range of conditions, a large number of parameters and tolerances in my code have been set to fixed values. Of particular note is that the numerical tolerances have been set such that the resultant stellar models have an accuracy of 1 part in 10,000. As such, these models are not suitable for research (such as helio and astro-seismology) that requires high precision stellar models.

Credits

The stellar evolution code used in these calculations is based upon the Yale stellar evolution code which was developed by Pierre Demarque and his students over a number of years. Brian Chaboyer has modified the code over the years, and custumized the code for use with the Java applet. The Java web server and applet was written by Susan Schwarz from Dartmouth's Research Computing department.

The creation of this web interface to a state of the art stellar evolution computer code was made possible by an NSF CAREER award, a Cottrell Scholar award from the Research Corporation and a Cheheyl Fellowship from Dartmouth College, all to Brian Chaboyer.