Illustration of a magnetar./ESA

A mysterious radio signal from space may have come from within our galaxy

The call is coming from inside the house. Or, in this case, the galaxy.

On April 28, scientists detected a burst of radio and x-ray signals coming from a star within the Milky Way galaxy. It lasted barely half a second, but just that blip of energy was enough to make it the first Fast Radio Burst (FRB) to originate so close to home. While FRBs aren't a newly discovered phenomenon, the proximity of this FRB is giving researchers hope that they can learn more about the origins of this mysterious signal.

According to three studies published in the journal Nature, the radio bursts appear to be coming from a special type of neutron star. A neutron star is basically a dead star. It's what happens when a star runs out of fuel and its core collapses. Gravity ends up smushing the protons and electrons together until there's nothing but a dense, neutron-rich center.

Neutron stars are wild enough on their own, but the one that sent out the FRB is even more exceptional than usual. This star, named SGR 1935+2154, is a magnetar — a type of neutron star that has a particularly strong magnetic field.

If you look at an artist's impression of a magnetar, you'll probably see a round core with a bunch of loops around it. The loops are drawn depictions of magnetic field lines.

Artist's impression of a radio bursting magnetar./ESA

The moment the magnetar set off a burst of radio signals, it pinged observatories all around the world. Scientists in Canada, China, the U.S., Russia, and Europe all scrambled to study the event. Together, these teams created a clear picture about the origins of the signals.

"This result is also a great example of how when international teams of scientists come together to study a phenomenon in different ways, we learn more about it," said one study author, Christopher Bochenek, in a briefing.

Although FRBs were first discovered in 2007, the source of them have baffled researchers throughout the decades. The signals were always too far away to pinpoint where they came from. But the close proximity of this magnetar, located just 30,000 light years away, allowed researchers to spot the source of the FRB for the first time.

"We've never seen a burst of radio waves, resembling a Fast Radio Burst, from a magnetar before," said Sandro Mereghetti, lead author of another study that detailed FRB findings from the magnetar, in an ESA statement. "It truly is a major discovery, and helps to bring the origin of these mysterious phenomena into focus."

With this finding, scientists can mark magnetars down as a possible source of other radio bursts they detect. But why these dead stars are sending out signals in the first place is yet another muddled part of the mystery.