Brightest and hottest stars have close, turbulent relationships, study suggets
The brightest and hottest stars in our galaxy tend to have short, violent lives, often drawing gas from each other and frequently merging to form a single star, a new study indicates.
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The researchers found that almost three-quarters of these stars have close companions. Most of these pairs are also close enough to interact with one another, with mass being transferred from one star to the other in a sort of stellar vampirism. About one-third of these binary systems are even expected to eventually merge to form a single star, the researchers said.Skip to next paragraph
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The results of the study indicate that massive stars with companions are more common than was once thought, and that these heavyweights in binary systems evolve differently than single stars — a fact that has implications for how scientists understand galaxy evolution.
"It makes a big difference for understanding the life of massive stars and how they impact the whole universe," said de Mink.
Big stars with a big impact
Type O stars make up less than 1 percent of the stars in the universe, but they have powerful effects on their surroundings. The winds and shocks from these stars can both trigger and halt star formation processes, the researchers said.
Over the course of their lives, culminating in the supernova explosions that signal their death, these massive stars also produce all the heavy elements in the universe. These elements enrich galaxies and are crucial for life.
But for massive stars in close binary systems, the interactions between the pair impact the evolution of both stars.
With vampire stars, the lower-mass star sucks fresh hydrogen from its companion, substantially increasing its mass and enabling it to live much longer than a single star of the same mass would, the researchers explained. The victim star, on the other hand, is left with an exposed core that mimics the appearance of a much younger star.
These factors could combine to give researchers misleading information about galaxies and the stars within them.
"The only information astronomers have on distant galaxies is from the light that reaches our telescopes," said Sana. "Without making assumptions about what is responsible for this light, we cannot draw conclusions about the galaxy, such as how massive or young it is. This study shows that the frequent assumption that most stars are single can lead to wrong conclusions."
The researchers report their findings in the July 27 issue of the journal Science.
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