For at least the past 10 years, a steady source of energy has been emitting signals from the outskirts of the Milky Way. The mysterious signal repeats every three hours in bright pulses that last about one minute. Astronomers believe they have identified the source of the signal, but their discovery has led to new mysteries that they must now solve.
The discovery. A team at the International Center for Radio Astronomy Research in Perth in Western Australia recently discovered the longest-period radio transient ever detected. Astronomers identified the source of this unprecedented signal and proposed a possible explanation for how these unusual transient events are generated.
Some context. Astronomical objects with changing magnetic fields, such as the Sun or Jupiter, can produce radio signals. Radio transients are brief bursts of energetic emissions, often produced by rotating neutron stars.
Long-period transients are a rare and poorly understood subset of this phenomenon, making the recent finding particularly significant.
The newly discovered transient. The object in question is named GLEAM-X J0704-37. It’s located on the outskirts of the Milky Way, in the Puppis constellation, around 5,000 light-years away. The Puppis constellation is an area with relatively few stars. Because of this, researchers are confident that a specific star system is responsible for generating the radio signals.
As mentioned earlier, the unprecedented energy pulse lasts about a minute and has occurred every three hours for at least the past 10 years. Observations from the MeerKAT telescope in South Africa have revealed that it’s traced back to an M dwarf.
Something’s amiss. When identifying the source of the signal, a new question emerged. An M dwarf alone couldn’t produce the amount of energy observed. However, additional observations made with the SOAR telescope in Chile confirmed the star’s spectrum and verified its classification as an M-type red dwarf star.
M dwarfs are low-mass stars that have a tiny fraction of the mass and luminosity of the Sun. They account for about 70% of the stars in the Milky Way. However, none of them are visible to the naked eye. So, what could explain the signal?
Explanation. Research published in The Astrophysical Journal Letters suggests that the M dwarf is part of a binary system with a white dwarf, which is the remnant core of a star that has exhausted its nuclear fuel. Together, they generate the radio signals documented for a decade in the Murchison Widefield Array archives in Western Australia.
The research team plans to conduct follow-up observations to confirm the nature of the newly discovered system. Astronomers will then further explore this extreme astrophysical phenomenon, which may also occur in other similar systems.
Image | ICRAR/Curtin | Jacob Spence
View 0 comments