Scientists observing a curious neutron star in a binary system known as the ‘Rapid Burster’ may have solved a forty-year-old mystery surrounding its puzzling X-ray bursts. They discovered that its magnetic field creates a gap around the star, largely preventing it from feeding on matter from its stellar companion.
“We’re made of star stuff,” astronomer Carl Sagan famously said. Nuclear reactions that happened in ancient stars generated much of the material that makes up our bodies, our planet and our solar system. When stars explode in violent deaths called supernovae, those newly formed elements escape and spread out in the universe.
Monster black holes sometimes lurk behind gas and dust, hiding from the gaze of most telescopes. But they give themselves away when material they feed on emits high-energy X-rays that NASA’s NuSTAR mission can detect. That’s how NuSTAR recently identified two gas-enshrouded supermassive black holes, located at the centers of nearby galaxies.
Astronomers may have solved the mystery of the peculiar volatile behaviour of a supermassive black hole at the centre of a galaxy known as Markarian 1018 some 590 million light-years away. Combined data from NASA’s Chandra X-ray Observatory and other observatories suggest that the black hole is no longer being fed enough fuel to make its surroundings shine brightly.
Using X-ray observatories, astronomers have found evidence for what is likely one of the most extreme pulsars, or rotating neutron stars, ever detected. The source exhibits properties of a highly magnetised neutron star, or magnetar, yet its deduced spin period of 6⅔ hours is thousands of times longer than any pulsar ever observed.
Supermassive black holes do not give off any of their own light, hence the word “black” in their name. However, many black holes pull in surrounding material and emit powerful bursts of X-rays. Collectively, these active black holes can be thought of a cosmic choir, singing in the language of X-rays. Their “song” is what astronomers call the cosmic X-ray background.
NASA’s Nuclear Spectroscopic Telescope Array, or NuSTAR, has captured the best high-energy X-ray view yet of a portion of the Andromeda Galaxy, our nearest large neighbouring spiral galaxy. The space observatory has observed 40 “X-ray binaries” — intense sources of X-rays comprising a black hole or neutron star that feeds off a stellar companion.