Astronomers using the Murchison Widefield Array in Western Australia have identified a new source for long-period radio transients, tracing flashing radio waves arriving every 7.9 minutes to a pulsing object believed to be a white dwarf pulsar orbiting a G-type star almost identical to the Sun. Published today in Nature Astronomy, the discovery is the first to link such a transient to a binary system where the partner star resembles our own Sun rather than the red dwarfs seen in previous examples.
The signal was detected using a search method developed by PhD student Csanád Horváth. The pulses appear during a window of about six hours, followed by 26 hours without pulses. The most natural explanation, the researchers say, is a binary system with a 32-hour orbit, with radio pulses visible only when the stars are lined up in the right way.
Long-period radio transients have puzzled astronomers since the first was discovered in 2022. These objects emit bright flashes of radio waves every few minutes to hours. Some identified sources have been traced to binary systems of a white dwarf and a small, cool red dwarf star.
The new source broke this pattern. The MeerKAT telescope in South Africa located the source to a single faint star, and the Keck telescope in Hawaii recorded its spectrum, revealing it to be a G-type star almost the same mass and temperature as the Sun.
To assess whether the pulsing object was a neutron star, the researchers examined the timing of the pulses. The arrival times shift by up to four seconds earlier or later than expected during the orbit, revealing the size of the orbit. The spectrum shows the Sun-like star barely wobbles, meaning it is much heavier than the pulsing object. Combining these measurements, the pulsing object has a mass about two-thirds that of the Sun, too low to be a neutron star; the researchers believe it is a white dwarf pulsar.
The researchers believe such systems may be common in the universe but are hard to see with optical telescopes because the dim white dwarf is hidden in the glare of the bright star. Radio pulses cut through the glare; if more long-period transients turn out to be hiding white dwarfs around bright stars, radio surveys could uncover a whole hidden population of such objects.
This is significant because some white dwarf binaries are thought to be the ancestors of Type Ia supernovae. Astronomers use these exploding stars as standard candles to measure interstellar distances and the expansion of the universe. Finding these systems could deepen the understanding of this process.
Analysis
Why This Matters
- Solves a key mystery in radio astronomy by identifying a white dwarf pulsar around a Sun-like star.
- Could reveal a new population of white dwarf binaries hidden from optical view.
- Provides insight into the progenitors of Type Ia supernovae, crucial for cosmology.
Background
Long-period radio transients were first identified in 2022, emitting regular radio flashes every few minutes to hours. The first transients with identified sources were traced to binary systems containing a white dwarf and a red dwarf star. This new discovery is the first linking such a transient to a white dwarf binary where the companion star resembles our own Sun.
What to Watch
- The next generation of radio telescopes, such as the SKA Observatory, is expected to find many more long-period transients.
- Astronomers will investigate whether these systems are commonly hiding white dwarfs around bright stars.
- Follow-up studies will explore the link between these binaries and Type Ia supernovae.
Checked
12 claims in this story checked against 1 source: 11 supported.
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- SupportedThe radio flashes have been traced to a source associated with a Sun-like star.The Conversation – Articles (AU): “The source of the newly discovered long-period radio transient is precisely located to a G-type star like the Sun.”
- SupportedThe Sun-like star’s partner is believed to be a white dwarf pulsar.The Conversation – Articles (AU): “We believe the pulsing object is a white dwarf pulsar, the first found in orbit around a Sun-like star.”
- SupportedThis is the first long-period radio transient found in a system with a G-type, Sun-like star.The Conversation – Articles (AU): “We report the first discovery of a different source for one of these enigmatic intermittent broadcasters: it still involves a white dwarf, but also a star much like our own Sun.”
- Partly supportedThe star is almost identical to the Sun.The Conversation – Articles (AU): “The result was a surprise: this was not a tiny red dwarf, but a G-type star almost the same mass and temperature as our own Sun.”
- SupportedThe discovery was published today in Nature Astronomy.The Conversation – Articles (AU): “In new research published today in Nature Astronomy, we report the first discovery of a different source for one of these enigmatic intermittent broadcasters: it still involves a white dwarf, but also a star much like our own Sun.”
- SupportedUsing the Murchison Widefield Array in Western Australia, researchers detected flashes arriving every 7.9 minutes.The Conversation – Articles (AU): “In late 2024, we were looking for new long-period transients using the Murchison Widefield Array radio telescope in Western Australia. Using a search method developed by PhD student Csanád Horváth, we spotted something: short flashes of radio waves, arriving like clockwork every 7.9 minutes.”
- SupportedThe pulses appear for about six hours, followed by 26 hours without pulses, consistent with a 32-hour binary orbit.The Conversation – Articles (AU): “The pulses only appear during a window of about six hours, followed by 26 hours without pulses. The most natural explanation is that the system is a binary: two stars orbiting each other once every 32 hours”
- SupportedMeerKAT pinpointed the source to a patch containing a single faint star, and Keck recorded its spectrum, identifying it as a G-type star.The Conversation – Articles (AU): “The MeerKAT telescope in South Africa pinpointed the source to a tiny patch of sky containing a single faint star. We turned to the Keck telescope in Hawai’i to record the star’s spectrum”
- SupportedThe pulsing object’s mass is about two-thirds the Sun’s, too low for it to be a neutron star; researchers believe it is a white dwarf pulsar.The Conversation – Articles (AU): “we can work out that the pulsing object is about two-thirds as heavy as the Sun. That means it’s too light to be a neutron star. We believe the pulsing object is a white dwarf pulsar”
- SupportedResearchers believe such systems may be common but are difficult to see because the bright star’s glare hides the white dwarf.The Conversation – Articles (AU): “We think systems like this are probably quite common in the universe, but white dwarfs next to bright stars are very hard to see. The glare of the bright star hides the faint white dwarf.”
- SupportedRadio surveys could uncover a hidden population of such systems if more transients turn out to involve white dwarfs around bright stars.The Conversation – Articles (AU): “If more long-period transients turn out to be hiding white dwarfs around bright stars, radio surveys could uncover a whole undiscovered population that optical and X-ray telescopes miss.”
- SupportedSome white dwarf binaries are thought to be ancestors of Type Ia supernovae, which astronomers use as standard candles to measure distances and the universe’s expansion.The Conversation – Articles (AU): “This is important because some white dwarf binaries are thought to be the ancestors of Type Ia supernovae. Astronomers use these exploding stars as “standard candles” – reference points to measure interstellar distances and the expansion of the universe.”
