Sun's 'Long-Lost' Sister Found With Possible Earth-Like Exoplanets
Though the ancient Greeks described the Sun god Apollo's twin as Artemis the chaste huntress, an astronomer at the University of Texas says he's found the Sun's true "solar sibling" — a star 110 million light years from Earth in the constellation Hercules.
Likely born of the same star dust some 4.5 billion years ago, the Sun's new twin may offer new insights into the genesis of planet earth as well as how the solar system became habitable for life. "We want to know where we were born," astronomer Ivan Ramirez, said in a press statement. "If we can figure out in what part of the galaxy the sun formed, we can constrain conditions on the early solar system. That could help us understand why we are here."
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Hanging in the lower leg of the constellation Hercules, Star HD 162826 is 15 percent larger than the sun and may be seen in the night sky near the star Vega. In searching for the Sun's twin, Ramirez and his colleagues made a study of 30 stars identified by other astronomers as potential solar siblings. However, only one star met the "dynamical and chemical criteria for being a true sibling of the Sun." That star has a chemical composition like the Sun's as well as similar orbital travels through space and time known as "dynamics."
By happy coincidence, astronomers from the University of Texas had been studying the same star for 15 years at the McDonald Observatory in Fort Davis, Texas, concluding that the star system lacked any "hot Jupiters," like the Sun's own large gaseous planets. Still, the observations leave wide open the possibility that smaller earth-like exoplanets may exist in the system.
"The idea is that the Sun was born in a cluster with a thousand or a hundred thousand stars. This cluster, which formed more than 4.5 billion years ago, has since broken up," Ramirez says. "A lot of things can happen in that amount of time."
Although once close in the Milky Way, the stars born of that cluster long ago went their separate ways, moving to different corners of the galaxy. Yet HD 162826 remains tantalizing close, as astronomers listen attentively for that long-distance phone call from E.T.
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