Astronomers Puzzle Over Short-Lived Glowing Green Light Bursts
by Jason Daley Smithsonian.com
Earlier this week, NASA released a stunning image of the so-called Fireworks galaxy, which certainly lives up to its nickname. In the frame, two blue beams and one large splash of green paint the already dazzling galaxy.
But don’t dust off your telescope lenses just yet. Those pops of color aren’t within the visible light spectrum. They’re extremely bright bursts of X-ray radiation—and the green glow vanished in the course of ten days.
At first, NASA’s NuSTAR space observatory, which was searching for supernovas, didn’t spot the green X-ray emission, known as an ultraluminous X-ray source (ULX), according to a NASA press release. But ten days later, another look at the Fireworks galaxy revealed that the source—dubbed ULX-4—had sparked to life. Another ten days after that, the Chandra X-ray Observatory failed to relocate ULX-4. The observations are detailed in The Astrophysical Journal.
“Ten days is a really short amount of time for such a bright object to appear,” says the study’s lead author and Caltech astrophysicist Hannah Earnshaw in a statement. “Usually with NuSTAR, we observe more gradual changes over time, and we don’t often observe a source multiple times in quick succession.