Astronomers spot another giant black hole in our backyard

first_imgAstronomers have long known that there is a supermassive black hole—known as Sagittarius A*—at the center of our galaxy. Now, a team of astronomers says they have found another one, not quite as big, orbiting 200 light-years from the center of the Milky Way. The team didn’t set out to find a black hole. While it was using the National Astronomical Observatory of Japan’s 45-meter Nobeyama radio telescope to study an enigmatic gas cloud called CO-0.40-0.22, something unusual caught their eye: an unusually wide range of speeds in the cloud’s gas molecules, suggesting that something massive is accelerating them. Observations at x-ray and infrared wavelengths didn’t reveal any big objects in the cloud. As the team describes in Astrophysical Journal Letters, a simulation of the gas movement in the cloud suggested the cause was a compact object 0.3 light-years across with a mass 100,000 times that of our sun. The best explanation for such an object, which doesn’t appear at other wavelengths, is an intermediate-mass black hole (imagined by an artist, above). Astronomers have long predicted the existence of black holes larger than those formed from single stars, but smaller than the million or billion solar mass ones lurking at the centers of galaxies. But so far there is little evidence for their existence. If CO-0.40-0.22 does prove to contain such an object, it will be a rare beast, indeed, and right in our backyard.last_img

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