Scientists have recently found that odd stars known, as “blue stragglers” may be the product of collision between two, and possibly more, older stars. This may result in finding out a 50 year-old mystery of the blue stragglers.
Even in “dense” areas stars a typically billions, if not, trillions, of miles apart. But stars may have the occasional chance to collide in global clusters, which are dense groupings of up to a million stars wit tightly packed cores. Some global clusters are among the oldest structures in the universe, about 15 billion years old, all the stars in the clusters are known as red giants that have puffed up to there outermost atmospheres. In these clusters the presence of blue stragglers have baffled astronomers since the 1950’s. Each of these stars less than a billion years old.
Scientist recently realized that the collision of the older stars in the clusters could merge together to form one young one. Because of the stars mass a color determining the age of the star. Red being cool, blue being hot. Heavy stars burning fast, lighter stars undergoing a slow burn.
Blue stragglers appear to be formed by the collision of stars known as main sequence turnoff stars. These are stars that have reached the end of their lives and are about to become red giants. Four of the Five blue stragglers examined were just the mass the astronomers expected had two stars collided. The fifth was so much heavier than expected that Saffer, C. Rex, of Villanova University, suspects that three or more stars collided from it. When astronomers have made a computer model, and one scenario is that a lighter star crashes into a heavier one at 500,000 miles per hour, leaving behind a huge wake. Then buries itself at the core of the larger star, setting up massive shock waves on the star’s surface. The newly formed, combined star can take anywhere from hundered of thousands of years to ten million years to settle down into a new, stable star.
Other astronomers are looking for “near-misses”. If two stars deal each other a glancing blow, a red giant could conceivably have its outer atmosphere stripped away, exposing it hot core, which is normally destined to become a compact star known as a white dwarf. Adrienne Cool, an astronomer at San Francisco University, may have found some of these, which appear to be much less massive than typical white dwarfs.
“Crasing Stars Create Hot Blue Youths.” Today’s Science On File August 2000:312.