Study of distant star suggests 'feisty' childhood of Earth's sun

CAMBRIDGE, Mass., June 5 (UPI) -- Study of a distant young star suggests the sun was active and "feisty" in its infancy, growing in fits and starts and burping out X-rays, U.S. astronomers say.

Nancy Brickhouse of the Harvard-Smithsonian Center for Astrophysics and colleagues say they've reached this conclusion by studying the young star TW Hydrae, located about 190 light-years from Earth in the southern constellation Hydra the Water Snake.

"By studying TW Hydrae, we can watch what happened to our sun when it was a toddler," Brickhouse said Wednesday at a meeting of the American Astronomical Society.

TW Hydrae is an orange, type K star weighing about 80 percent as much as the sun, the researchers said. At about 10 million years old it is still growing by accreting gas from a surrounding disk of material that might contain newborn planets.

That accretion is a clumpy and episodic process, they found, with changes in the X-ray output of the glowing gas.

"The accretion process changes from night to night," research team member Andrea Dupree said. "Things are happening all the time."

Astronomers have known young stars are much more magnetically active than the middle-aged sun, but at TW Hydrae they can actually probe the interplay between the star's magnetic fields and the protoplanetary disk, a Harvard-Smithsonian release said Wednesday.