Mysterious radio signals are coming from rare binary star system
A radio telescope in Australia has picked up strange radio signals coming from 4,000 light-years away from Earth. The signals flash like a pulsar but with abnormally long intervals and durations. Similar signals have been found 15,000 light-years and 5,000 light-years away, the latter emitting flashes lasting between 30-60 seconds every 2.9 hours.
Binary star system suspected as source of signals
The source of these signals is thought to be a binary star system, which includes a red dwarf and a white dwarf star. Curtin University's Natasha Hurley-Walker emphasized the difficulty in spotting these sources because of crowded star fields. However, she said the new discovery is in a less crowded region, which helps with identification.
First signal found in Murchison Widefield Array data
The first signal, dubbed GLEAM-X J162759.5-523504.3, was detected in archival data from the Murchison Widefield Array (MWA) and emitted radio waves every 18.18 minutes until March 2018. The second signal, GPM J1839-10, was detected in follow-up MWA observations and had been active since at least 1988. Pulsars are known to emit pulsing signals but typically on much shorter timescales than these new findings.
Third signal traced to red dwarf star
The third signal, GLEAM-X J0704-37, was also discovered in MWA archival data and lies in the southern constellation of Puppis. Using the MeerKAT radio telescope array, the researchers were able to pinpoint the source of GLEAM-X J0704-37. They found an M-type red dwarf star to be the source of the signals. Red dwarfs are common in the Milky Way but don't usually emit such radio waves.
White dwarf star suspected as binary companion
The team believes GLEAM-X J0704-37's strange emissions are caused by its binary companion, probably a white dwarf star. White dwarfs are dense corpses of dead stars with up to 1.4 times the mass of the Sun. Hurley-Walker explained their data indicates "it is in a binary with another object," probably a white dwarf fueling the radio emission. The binary system could involve material transfer from the red dwarf to the white dwarf.
Further observations planned to confirm star hypothesis
Further observations are planned to confirm this hypothesis and find direct evidence for the white dwarf's presence. If confirmed, GLEAM-X J0704-37 would be classified as a white dwarf pulsar, one of the rarest types of stars in our galaxy. The research findings have been published in The Astrophysical Journal Letters.
