The ASKAP radio telescope in Australia recorded a strange repeating signal that changes character every 53.8 minutes and goes into three different states.
The signal, called ASKAP J1935+2148, is unlike anything we’ve ever seen. It emits bright flashes lasting 10 to 50 seconds with linear polarization.
In other cases, it emits weaker, circularly polarized pulses that last only 370 milliseconds. Sometimes the signal disappears completely. The study was published in the journal Nature Astronomy.
“What’s intriguing is that this object exhibits three different radiation states, each with completely different properties,” says lead author Dr. Manisha Caleb.
Astronomers consider two main versions: a neutron star and a white dwarf. But none of these options explain the strange properties of the signal. Neutron stars are known for their radio signals, but they typically spin at speeds of seconds or fractions of a second per rotation.
The ASKAP J1935+2148 signal spins too slowly, which contradicts our understanding of neutron stars. White dwarfs, although they may rotate slowly, should not emit radio signals with these properties.
This isn’t the first time that repeated radio signals from space have confused astronomers. A few years ago, a signal with an 18-minute cycle was discovered, which also contradicted existing theories. The new signal is even more mysterious; it not only has a longer cycle, but also exhibits more complex characteristics.
Further observations are needed to unravel the mystery of ASKAP J1935+2148. Studying the signal could lead to a revision in our understanding of the physics of neutron stars and white dwarfs.
“It may even prompt us to rethink our long-standing understanding of neutron stars or white dwarfs. About how they emit radio waves and what their population is in our Milky Way Galaxy,” Caleb said.
