DEBORAH NETBURN | May 19, 2014, 11:00 AM
A star born from the same cloud of gas as our sun 4.5 billion years ago has been found at last, astronomers say.
This solar sibling is a little bigger than our sun, and a little hotter at its surface. But an international team of researchers says it has the same chemical fingerprint as the star at the center of our solar system, leading them to conclude both stars were born in the same stellar nursery, at the same time.
“Stars that were born in different clusters have different compositions,” said Ivan Ramirez, an astronomer at the University of Texas at Austin. “If a star has the exact same chemical composition as our sun, that establishes that they were born in the same place.”
Ramirez is the lead author of a paper about the discovery that will be published June 1 in the Astrophysical Journal.
Like most stars, our sun emerged from an immense cloud of gas and space dust that gave rise to 1,000 to 10,000 stars. Those baby stars stayed clustered together for hundreds of millions of years — a relatively short time on the astronomical scale.
But as they grew up, their cluster broke up and the individual stars began to drift apart. Billions of years later, these stellar siblings are now scattered across the Milky Way galaxy.
Our sun’s newly discovered solar brother from the same gas-cloud mother is known as HD 162826. It is just 110 light years away from our sun, which Ramirez said is remarkably close.
“It is almost certain that if there is another star like this one this close to us, we would have found it already,” he said, “so the next siblings we find are going to be further away.”
Ramirez wasn’t expecting to find a solar sibling even this close to our own sun. In an interview with the Los Angeles Times, he explained that the original intent of his research was to determine efficient ways of identifying our sun’s closest relatives in the future when surveys like space-based telescope Gaia’s provide astronomers with a flood of new data.