Triton Resource Featured Project

The first generation of stars are believed to have formed about 150-300 million years after the big bang, when the universe would have been mostly neutral, and completely dark to human eyes. These first generations of objects are unreachable by telescopes currently in use, but are ideally suited to computer simulations. The initial conditions for their formation are well known, and the set of physics that governs their formation is relatively simple, so they make for ideal problem spaces for supercomputer laboratories.

This project runs simulations for early star formation on the Triton Resource. The simulations take advantage of Triton's large memory capacity to efficiently process numerous runs using less compute time than is required on lower-memory systems. One particular advantage gained from running these simulations on Triton is the "Princeton Twist", which is described below.

To simulate the manner in which these stars form, a random sample of the universe is generated, into which the correct initial conditions are poured. By following and updating the set of equations that governs the way matter would evolve in that region — hydrodynamics, gravity, molecular chemistry — structures naturally arise. In regions where more interest phenomena are occurring, such as overdense regions or regions unstable to collapse, higher resolution elements are inserted. For a typical simulation, this typically occurs on the order of 30 times, such that the finest region simulated is 2^30 times smaller than the coarsest region simulated inside that very same computer simulation. The physical model describing the way the gas evolves is valid for many orders of magnitude in density, and for that reason the resolution available easily covers scales from galaxies down to sub-stellar radii.

Visualizing a Simulation

From previous calculations, it appeared that the first generation of stars were always very massive, forming in isolation. Recent studies, following the collapse with an expanded physical model and higher resolution, have suggested that perhaps it is not always so: sometimes the primordial clouds break into multiple clumps, each of which could subsequently form an individual star. However, because the number of calculations using this expanded physical model is currently quite low, a statistical sampling needs to be conducted in order to constrain the rate of fragmentation — the "initial mass function."