Caption: An artist's time series shows two stars colliding to form a blue straggler star. The two stars begin in the top left of the image on a collision course, perhaps as a result of a gravitational dance with a third star in a star cluster. During the collision, the two stars merge to form a new star: a blue straggler. This more massive, rapidly rotating and bluer star is seen in the bottom left of the image, partnered with the third star that participated in the initial dance, leaving a newly formed binary star containing the blue straggler. Crashing stars, an idea once thought far-fetched by astronomers, emerged as one possibility for the formation of blue stragglers from observations by UW-Madison astronomers.
Illustration: Barry Roal Carlsen
Date: December 2009