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. Image credit: Barry Roal Carlsen

“These blue, luminous stars should have used up their hydrogen fuel and flamed out long ago,” explains Robert Mathieu, a University of Wisconsin-Madison astronomer. “Yet they are still here. By some means or another, they have recently increased their mass, their fuel supply.” Now, Mathieu and Wisconsin colleague Aaron Geller, writing in the journal Nature, show that blue stragglers, in most if not all cases, steal that mass from companion stars and that they sometimes do so by crashing into their neighbours, a scenario once thought far-fetched by astronomers.

Source: University of Wisconsin-Madison