Free Astronomy Magazine May-June 2019

50 MAY-JUNE 2019 SPACE CHRONICLES Black holes are objects with such strong gravity that everything, in- cluding light, is sucked in and can- not escape. Because black holes do not emit light, astronomers must infer their existence from the ef- fects their gravity produce in other objects. Black holes range in mass from about 5 times the mass of the Sun to supermassive black holes millions of times the mass of the Sun. Astronomers think that small black holes merge and gradually grow into large ones, but no one has [almost] ever found an interme- diate mass, hundreds or thousands of times the mass of the Sun. A research team led by Shunya Takekawa at the National Astro- nomical Observatory of Japan no- ticed HCN–0.009–0.044, a gas cloud moving strangely near the center of by ALMA Observatory Hiding black hole found A stronomers have detected a stealthy black hole from its effects on an interstellar gas cloud. This intermediate mass black hole is one of over 100 million quiet black holes expected to be lurking in our galaxy. These results provide a new method to search for other hidden black holes and help us un- derstand the growth and evolution of black holes.