ATLANTA -- For decades, scientists have observed that Regulus, the brightest star in the constellation Leo, spins much faster than the sun. But thanks to a powerful new telescopic array, astronomers now know with unprecedented clarity what that means to this massive celestial body.
Most stars rotate sedately about their spin axes, McAlister says. The sun, for example, completes a full rotation in about 24 days, which means its equatorial spin speed is roughly 4,500 miles per hour. Regulus' equatorial spin speed is nearly 700,000 miles per hour and its diameter is about five times greater than the sun's. Regulus also bulges conspicuously at its equator, a stellar rarity
"We're looking at the star essentially equator-on, and the spin axis is tilted about 86 degrees from the north direction in the sky," he says. "But, curiously enough, the star is moving through space in the same direction its pole is pointing. Regulus is moving like an enormous spinning bullet through space. We have no idea why this is the case."