MADISON, Wis. -- Starting around 1950, a series of advances formed a clear and accepted picture of how individual stars are born, evolve and die. As they age, the changing patterns of color, light output, size and lifespan of stars are predictable. Every star like the sun will become a red giant, a planetary nebula and finally a white dwarf.
But half of all stars are in binaries -- pairs of stars that orbit each other. Half of binary stars orbit so close that gravitational interaction significantly affects their evolution and demise. Today, scientists led by Robert Mathieu, a professor of astronomy at the University of Wisconsin-Madison, and his former student Natalie Gosnell confirmed one of the possible explanations for a common group of exceptions: the blue stragglers.