Blue Stragglers Suck the Life from Their Companion Stars to Stay Younger for Longer
Most stars born, evolve and die in similar ways. But for some stars, called binary stars, the gravitational force of their partner impacts their lives. Now, scientists are taking a closer look at a strange group of exceptions: blue stragglers.
Blue stragglers look younger and brighter than their age would suggest. In fact, they skirt the clean and clear rules of stellar evolution. Since their discovery in 1953, blue stragglers have eluded explanation. Now, scientists have found that over three-quarters of blue stragglers have stellar companions, which may explain them a bit more thoroughly.
In this latest study, the researchers used the Hubble Space Telescope to study the "colors" of far ultraviolet light coming from blue stragglers and their companions. At a distance of 5,500 light years, the blue straggler binary appears as a single point of light. By analyzing the amount of ultraviolet light, though, the researchers spotted the unmistakable signal of a white dwarf.
In fact, the researchers believe that the white dwarf was once a red giant that donated hydrogen gas to the blue straggler for eons until it was eventually transformed into a white dwarf.
"Our understanding of single-star evolution is one of the great intellectual achievements of the last century," said Robert Mathieu, one of the researchers, in a news release. "We began with points of light in the sky, and with the application of new instrumentation, the physics breakthroughs of the last century, and computers, we took those points of light and turned them into a narrative of star life. For the evolution of single stars like our sun, by and large, we got it right, from birth to death. Now we're starting to do the same thing for the one-quarter of stars that are close-orbiting binaries. This work allows us to talk not only about points of light, but also about the evolution of galaxies, including our own Milky Way. That's a big deal, and getting it right is an even bigger deal."
The findings are published in The Astrophysical Journal.
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