Gigantic Double Sun

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LOCATION: The constellation Centaurus

DISTANCE: 12,000 light-years from Earth

TIME TO REACH: 325 million years

WEATHER: 10,000°F


The star outside your spaceship’s windshield is a spectacular sight. HR 5171 A is a fireball 1,300 times larger than the Earth’s sun. It’s so big that if it were in our sun’s position, it would swallow up Earth beneath its 10,000°F surface. To look at it from your spaceship, you have to wear special goggles—this star is almost a million times brighter than our sun.


As you watch HR 5171 A burn, you notice something strange. An object is peeking over the horizon, growing larger and larger. It’s another sun—a smaller one that orbits the giant HR 5171 A. This small sun (though it’s still about 350 times larger than Earth’s sun) is snuggled up so close to its sister sun that they’re touching.


Even though it’s tiny compared to the giant HR 5171 A, the smaller sun has much stronger surface gravity. As it circles, it sucks hot, bright gas off of the larger star. The sister suns are enveloped in a big disk of swirling gas.


You fly in close to get a better look. Whoa! Your spaceship is blown backward by a gust of powerful wind. Magnetic fields are erupting from HR 5171 A, sending waves of a hot, electrically charged fluid called plasma shooting off its surface.


You glance down to see that the numbers on your instrument panel are flickering. The plasma is frying your electronics. You rev the engine and speed away before it’s too late.







• The star known as HR 5171 A is nearing the end of its life. When that happens, in a half million years or so, it will explode in a supernova so bright that it’ll be visible from Earth.


• To study HR 5171 A, scientists had the help of backyard stargazers, who trained their telescopes on the star and reported what they saw.

Text by Stephanie Warren Drimmer