test 1 Astronomy - May 2018 USA | Page 21

ASTRONEWS SINK IN. The surface of Jupiter’s moon Europa may be so porous that visiting spacecraft would sink into the world. Black hole lets out a double burp X-ray & optical New burp Old burp Astronomers believe that supermassive black holes at the centers of galaxies “flicker” on and off, alternately gob- bling up material, “burping” out bubbles of hot gas, and “napping” between meals. But while spotting a single out- burst isn’t rare, identifying the remnants of two past meals has never occurred until now. A team led by researchers at the University of Colorado Boulder published such a find in The Astrophysical Journal November 6, identifying two separate burps emitted by the galaxy SDSS J1354+1327 (or J1354, for short): one ancient and on the verge of dissipat- ing, and one hinting at a more recent meal. Because burps dissipate over time, they become increasingly difficult to see. “We happened to observe this galaxy at a time when we could clearly see evi- dence for both events,” said study leader Julie Comerford of CU Boulder in a press release. The researchers spotted a large, diffuse cone of gas extending 30,000 light-years below the galaxy’s bulge, where the supermassive black hole is located. The atoms in the gas were stripped of their electrons by a huge burst of radiation BAD MANNERS. Astronomers imaged the galaxy J1354, about 800 million light-years away, in X-rays and optical light. They saw the remnants of one ancient (blue-green emission) and one more recent (blue arc) burp. A nearby companion galaxy hints at a galactic collision that funneled material in toward the supermassive black hole, providing the meals that prompted those burps. from the black hole about 100,000 years ago. Above the bulge, they saw a shock wave 3,000 light-years away from the black hole, associated with a second, more recent meal. Between the two events, the black hole was likely much more dormant. “We are seeing this object feast, burp, and nap, and then feast and burp once again, which theory had predicted,” said Comerford. That theory also applies to the Milky Way. “Our galaxy’s supermassive black hole is now napping after a big meal, just like J1354’s black hole has in the past. So we also expect our mas- sive black hole to feast again, just as J1354’s has,” said Scott Barrows of CU Boulder. — A.K. Earth Mars 71.4 years (average) 2 minutes Jupiter, Saturn, Uranus, and Neptune Mercury Venus 30 seconds 1 to 2 seconds 1 minute FAST FACT The four outer planets have no solid surfaces. If you started at the top of their atmospheres, you’d fall for about a minute (choking all the way) before the intense atmospheric pressure crushed you. PLANETARY BODY. Science fiction movies sometimes show bad things happening to spacesuits. Indeed, films like The Martian and Total Recall attempt to visualize what would happen if a suit depressurized. But how long could an astronaut last without that first level of protection? Here are some rough estimates. — Michael E. Bakich DEATH’S HOT/COLD TOUCH W W W.ASTR ONOMY.COM 21