The researchers remain uncertain about the source of the radio waves being directed towards Earth.
The waves' characteristics defy existing models attempting to elucidate their origin.
Researchers report that for a span of 35 years,
the source has been emitting consistent 20-minute bursts of energy, exhibiting substantial fluctuations in brightness.
The emissions bear resemblance to the blasts emitted by pulsars or fast radio bursts, typically lasting milliseconds to several seconds.
However, the newly identified source emits radio signals pulsating at a period of 21 minutes, a phenomenon previously considered implausible by conventional explanations.
Pulsars, which are rapidly rotating neutron stars, emit radio blasts as they spin.
When one of these pulsars crosses Earth's path, the emissions can be detected momentarily and brightly, akin to being in the path of a rotating lighthouse's light.
Scientists posit that this process can only occur if the pulsar's magnetic field is robust and it rotates at a sufficient speed. Otherwise, there wouldn't be enough energy to observe the pulsar from Earth.
This concept has given rise to the "pulsar death line," which indicates that sources must rotate quickly and possess strong enough magnetic fields to be detectable.