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Too Close

May 18, 2014

Any wise space traveler knows not to get too close to a black hole. That’s because a black hole’s gravity is so strong that nothing can escape it — not even light, the fastest thing in the universe.

A few years ago, astronomers discovered a source of X-rays in the constellation Ophiuchus, which climbs the eastern sky this evening. The X-rays were coming from material plunging into a previously unknown black hole. Gravity and friction heat the material to such high temperatures that it emits X-rays before it falls into the black hole.

By monitoring the X-rays, astronomers made a further discovery: A small red star — a red dwarf — orbits the black hole. The red star is so close to the black hole that it’s losing gas to its dark partner. What’s more, of all the stars known to be orbiting black holes, this one is closest to its black hole — it orbits once every two hours and 25 minutes.

That means the red star probably lies less than a million miles from the black hole — and will continue to lose more and more mass to its ravenous partner. Eventually, the black hole may consume the entire companion. Without anything to feed it, the black hole really will be black — a ravenous beast that’s eaten its unwise prey.

Look for Ophiuchus quite low in the east by 10 or 11 o’clock. Although most of its stars are faint, it’s to the lower left of the bright golden planet Saturn, making it fairly easy to find the serpent bearer’s place in the sky.


Script by Ken Croswell, Copyright 2012

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