Telescope finds never-before-seen \'river\' of hydrogen in space

A never-before-seen river of hydrogen flowing in space may help explain how some spiral galaxies keep up a steady pace of star formation, a U.S. scientist says. Astronomer D.J. Pisano, using the Green Bank Telescope in West Virginia, discovered the very faint, very tenuous filament of gas streaming into the nearby galaxy NGC 6946, the National Radio Astronomy Observatory reported Tuesday. "We knew that the fuel for star formation had to come from somewhere. So far, however, we've detected only about 10 percent of what would be necessary to explain what we observe in many galaxies," Pisano, from West Virginia University, said. "A leading theory is that rivers of hydrogen -- known as cold flows -- may be ferrying hydrogen through intergalactic space, clandestinely fueling star formation. But this tenuous hydrogen has been simply too diffuse to detect, until now." Astronomers say a cold flow is hydrogen gas from intergalactic space that has never been heated to extreme temperatures by a galaxy's star birth or supernova processes. Pisano used the highly-sensitive Green Bank Telescope to detect the glow emitted by neutral hydrogen gas connecting NGC 6946 with its cosmic neighbors, strongly supporting a theory larger galaxies could receive a constant influx of cold hydrogen by syphoning it off other less-massive companions. Such flows could explain what is fueling the sustained star formation seen in NGC 6946 and similar spiral galaxies, astronomers said.