![]() ![]() All the extra heat may be stopping star birth. Superhot stellar gas ejected from the black hole might be heating up other gas clouds surrounding the galactic centre, which is bad news for star formation, because they form when gas is cool enough to condense into dense bundles. ![]() Bizarrely, the tiny fraction of gas our black hole does imbibe may get in because it has transferred some of its jitteriness to gas particles that are thrown outwards, possibly by the black hole’s own magnetic field lines. “The black hole wants to suck it in, but it cannot,” says Wang. That means the black hole should not get the blame for apparently turning up its nose at hot gas on its plate. “It’s very hard to get steam into the sink,” says Wang. ![]() This hot gas is tenuous and its particles zip around randomly, making it hard to corral. But the gas around Sagittarius A* is much hotter – collisions between stellar winds in the starry disc heat the gas to 10 million ☌ before it even starts to fall towards the black hole. Such gas is dense and flows in an orderly fashion into a quasar’s maw, like water swirling into a drain. Quasars are champion eaters because they slurp up relatively cool gas, below 1 million ☌. The researchers estimate that less than 1 per cent of the surrounding gas ultimately comes near enough to be eaten. They found that the gas gets hotter and less abundant the closer it is to the black hole. To find out what’s really going on, Wang and his colleagues used NASA’s Chandra X-ray Observatory to measure the temperature and brightness of gas at different distances from the black hole. Some scientists noted, though, that the brightness estimate assumed the gas coming from the stars was relatively cool, and that it could easily slip down the black hole’s gullet, says Daniel Wang of the University of Massachusetts in Amherst. But it does not seem to be swallowing that much material – if it were, it would shine 100 million times brighter in X-rays. A crowded disc of massive stars spins around it, and researchers had previously calculated that these stars should spew out enough gas in stellar winds to provide the black hole with about four Earths’ worth of meals over the course of a year. ![]() The Milky Way’s relatively dim black hole, known as Sagittarius A* (pronounced “a-star”), is decidedly not one of these gorgers. ![]()
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