Radio signals detected from rare ‘Blue Eye Pulsar’ after decades of silence
For the first time, astronomers have detected radio pulses from a class of neutron star that was thought to be intrinsically radio-silent. The discovery of faint radio signals from the so-called “Blue Eye Pulsar,” a young neutron star at the center of a supernova remnant roughly 4,600 to 10,000 light-years away in the constellation Centaurus, overturns a paradigm that had stood for decades.
The pulsar, formally designated as 1E 1207.4-5209 in X-rays and PSR J1210-5226 in radio, sits at the heart of the supernova remnant PKS 1209-51/52, the remains of a star that exploded more than 4,100 years ago. It belongs to a rare class known as Central Compact Objects (CCOs), young neutron stars that had never been detected in radio waves despite nearly 59 years of searching with major telescopes including the Green Bank Telescope, China’s FAST, and earlier campaigns with MeerKAT.
The discovery was published June 25 in Nature Astronomy by a team led by Dr. Lei Zhang of the National Astronomical Observatories of the Chinese Academy of Sciences and corresponding author Prof. Di Li of Tsinghua University.
Why the Blue Eye
The nickname comes from composite images combining radio data from the MeerKAT telescope array in South Africa with X-ray data from the eROSITA instrument. When the faint radio emission is overlaid on the X-ray image, the result shows a distinct blue, eye-like shape at the center of the supernova remnant. Prof. Di Li coined the name.
The detection was made possible by MeerKAT’s exceptional sensitivity. After a four-hour observation on January 5, 2024, the team detected a faint radio pulse repeating every 424 milliseconds, matching the neutron star’s known X-ray spin period exactly. A follow-up observation of 8.5 hours on October 18, 2025, confirmed the signal. The flux density was extremely low, roughly 21 to 33 microjanskys at 816 megahertz, comparable to a cellphone signal from the Moon.
The pulse is 77% linearly polarized, unusually high for a pulsar with such low spin-down luminosity, and shows 30% circular polarization. The polarization characteristics suggest the radio beam crosses our line of sight near the magnetic pole.
A spin glitch may have triggered the emission
A leading hypothesis for why the pulses were not detected earlier involves a “spin glitch,” a sudden increase in the neutron star’s rotation rate. X-ray observations detected a glitch in 2015, and the team found evidence of another significant glitch in 2025.
The glitch may have disrupted and reconfigured the star’s magnetic field geometry, either activating radio emission that was previously absent or boosting previously undetectable faint waves above the detection threshold. If the radio emissions fade as the star’s spin gradually returns to its pre-glitch rate, that would confirm the glitch-linked turn-on mechanism.
“These neutron stars were considered radio-quiet for nearly six decades,” said Prof. Di Li. “This discovery shows that silence does not mean absence. They may be whispering all along, and we just needed to listen more carefully.”
A hidden population of young neutron stars
The finding has implications that extend beyond a single object. The Milky Way may contain a large undiscovered population of extremely faint radio pulsars that current surveys miss entirely. Many supernova remnants lack detectable radio pulsars, and this discovery suggests the pulsars are there, just too faint to see with current sensitivity.
The neutron star’s characteristic age derived from its spin-down rate is 303 million years, wildly inconsistent with the true age of the supernova remnant of roughly 14,000 years. That discrepancy means the neutron star was born spinning very close to its current period, consistent with the “injected pulsar” scenario proposed by Narayan in 1987.
The discovery also has relevance for Supernova 1987A in the Large Magellanic Cloud, whose remnant likely contains a neutron star that has not been detected in radio. It may be a similarly faint CCO-like object.
MeerKAT, FAST, and the upcoming Square Kilometre Array are expected to discover many more such objects, potentially transforming our understanding of neutron star populations.
Sources: Space.com (Keith Cooper), Nature Astronomy (DOI: 10.1038/s41550-026-02899-2), arXiv:2512.17214v2, Tsinghua University