When astronomers point their radio telescopes towards space, they sometimes detect sporadic bursts of radio waves from the Universe. These phenomena, known as “radio transients,” can sometimes appear only once, and sometimes in regular cycles.

Possible location of the radio source.

The majority of radio transients come from pulsars, which are neutron stars spinning at dizzying speeds and emitting regular bursts of radio waves. However, a recent discovery defies this norm with an hour-long cycle, the longest ever observed.

This unusual transient, named ASKAP J1935+2148, was identified thanks to the ASKAP radio telescope in Australia. This radio telescope, equipped with a wide listening field, allows for the rapid detection of exotic phenomena.

During the initial observations, ASKAP captured ASKAP J1935+2148 due to its circularly polarized radio waves. Following this initial detection, additional observations were made with ASKAP and the MeerKAT radio telescope in South Africa.

ASKAP J1935+2148 belongs to a new class of long-period radio transients. Its cycle of 53.8 minutes is the longest ever recorded. Observations reveal three distinct states: bright linearly polarized bursts, weak circularly polarized pulses, and a silent phase with no pulses.

The origin of this signal remains mysterious. A slowly rotating neutron star is the main hypothesis, although a white dwarf, a dead star about the size of Earth, cannot be ruled out. A binary configuration with another star could also explain these radio emissions.

This discovery could challenge our understanding of neutron stars and white dwarfs. Further research is needed to identify the exact nature of ASKAP J1935+2148.