Welcome to the TRIPTYCH Homepage

TRIPTYCH is a computer program that simulates the collision of two stars, including the orbital trajectories, merger, and evolution of the merger product. The code therefore joins three branches of stellar astrophysics: dynamics, hydrodynamics and evolution. This program is a first step toward realistic dynamical simulations of star clusters that include stellar collisions and stellar evolution. TRIPTYCH can be run online via a web interface, or you can follow the instructions below for downloading and running TRIPTYCH on your own machine. If you would like to simulate the collision of three stars, check out TRIPLETYCH.

Currently, the dynamics of the two parent stars is treated using a Runge-Kutta integrator from Numerical Recipes, the hydrodynamics of the merger with MMAS, and the evolution of the product with Jarrod Hurley's SSE stellar evolution code. This program was initially thrown together quickly, with the MODEST goal of initially just getting something that produced results. The hope is that the physics in each stage, or at the interfaces between the stages, will be improved by the experts in that field. The parent star input models will be replaced with ones in the format produced by the freely available stellar evolution code Tycho. The stellar dynamics will be replaced with something more sophisticated from STARLAB. MMAS will be replaced with a more general collision module that, among other improvements, allows for the possibility that the two stars do not merge. The stellar evolution code will be replaced with one that uses the full structure and chemical composition information provided by the collision module.

The primary code developers and contributors to this project are Jarrod Hurley (AMNH), Piet Hut (IAS), James Lombardi (Vassar), Jun Makino (Tokyo), Steve McMillan (Drexel), Peter Teuben (Maryland), and Jessica Sawyer Warren (Rutgers), and will hopefully include many others in the future. The initial web interface was developed by Vicki Johnson (Interconnect).  Once we replace the Numerical Recipe routines, this code will be free software licensed under the GNU GPL.

This program is an outgrowth of the first MODEST workshop. MODEST stands for MOdeling DEnse STellar systems. For more information, see the MODEST homepage and the following summary article.

Getting Started with TRIPTYCH

TRIPTYCH can be run online via a web interface by clicking here. To download TRIPTYCH onto your own machine instead, simply click on the following link. To unpack this file, issue the either of the following commands from the command prompt.

tar xzvf triptych0.3.tar.gz


gunzip -c triptych0.3.tar.gz | tar xvf -

This will create a directory named triptych0.3 that contains the software package, as well as a sample parent star models and a sample input file. The README file in this directory discusses the package in more detail. But for a quick start, type the following commands:

cd triptych0.3

For an even faster start, replace the last command with

./triptych < sample_input

The sample_input file sets the initial conditions, as well as the output file names: Stellar dynamics data are written to the file dynamics.dat, a model of the merger product to remnant.dat, and information on the stellar evolution to evolution.dat. These files contain column headings or other internal indications to help make them (somewhat) self-describing.

Version Comparison

Version 0.3 provides a fix to a bug that could cause the evolution to hang in rare instances. Version 0.2 is the first one to implement the single-star evolution (SSE) routines and wrappers written by Jarrod Hurley. Version 0.1 implemented the "toy model" stellar evolution code written by Piet Hut and Jun Makino following the MODEST-1 meeting.


This material is based upon work supported by the National Science Foundation under Grants No. 0071165 and 0205991 at Vassar. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation. 

Please send any comments or suggestions to jamie.lombardi (at) allegheny.edu