The star, 18 Scorpii, sits about 47.5 light-years away in the constellation Scorpio, and has long-been suspected of being Sun-like. A team of researchers from Villanova University, however, used observations from four space-based observatories to separate 18 Scorpii from the chaff of thousands of candidates as a definite solar twin.
"Its only with consideration of age that these things start to pull away from each other until we found a match," said Villanovas Ryan Hamilton, who announced the twin stars identity during a meeting of the American Astronomical Society here. "And [18 Scorpii] is a very good match."
Human twins have different fingerprints, and so, too, with 18 Scorpii are there differences. The star burns slightly hotter than the Sun, at 5,789 degrees Kelvin compared to 5,777 degrees. It appears to rotate slightly faster than the Sun, taking 23 days to complete a rotation rather than the Suns 25.
At 4.2 billion years old, the distant star just a bit younger and more massive than the Sun too, but its still a valuable tool for astronomers hoping to understand stellar evolution. The Sun is about 4.5 billion years old, and astronomers believe it will last another five billion before reaching the end of its lifecycle.
"Finding Sun-like stars helps us determine whether our own Sun is a normal star," said Edward Guinan, a Villanova astronomy professor and co-investigator in the study.
The find was part of the ongoing Sun in Time program, a collaborative study between Guinan, Villanova astronomer Larry DeWarf and other researchers, to investigate the evolution of the Sun and Sun-like stars. The team pared down a huge collection of stars into just a dozen or so before settling on 18 Scorpii.
Like the Sun, 18 Scorpii is a middle-aged main-sequence star. It is visible to Earth observers, Hamilton said, as a bright star just off the left claw the Scorpio constellation. In addition to 18 Scorpii, Guinans team also studied Sun-like stars ranging in age from just a few 100 million years to about nine billion years old.
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