See-through galaxy

To peer into the galactic center of our own Milky Way galaxy, astronomers Silas Laycock and Josh Grindlay used the unique capabilities of the 6.5-meter-diameter Magellan Telescope in Chile. By gathering infrared light that more easily penetrates dust, the astronomers were able to detect thousands of stars that otherwise would have remained hidden. Their goal was to identify stars that orbit, and feed, X-ray-emitting white dwarfs, neutron stars or black holes — any of which could yield the faint X-ray sources discovered originally with NASA’s Chandra X-ray Observatory. Chandra previously detected more than 2,000 X-ray sources in the central 75 light-years of our galaxy. About four-fifths of the sources emitted mostly hard (high-energy) X-rays. The precise nature of those hard X-ray sources remained a mystery. Determining the nature of the sources can teach us about the star formation history and dynamical evolution of the region near the galactic center. “If we found that most of the hard X-ray sources were high-mass X-ray binaries, it would tell us that there had been a lot of recent star formation because massive stars don’t live long,” says Laycock. “Instead, we found that most of the X-ray sources are likely to be older systems associated with low-mass stars.” Their study was presented at the 205th meeting of the American Astronomical Society in San Diego, Calif.