Simulation Image (Tracer) (image) University of California - Santa Cruz Caption This is an image from a computer simulation shows a collision of two streams of interstellar gas, leading to gravitational collapse of the gas and the formation of a star cluster at the center. In this image, the gas streams were labeled with blue and red "tracer dyes," and the purple color indicates thorough mixing of the two gas streams during the collapse. Credit Y. Feng and M. Krumholz Usage Restrictions For use only with news stories about this research. Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.