Astronomers Discover Lowest-Mass Double Neutron Star System

Astronomers from the Chinese Academy of Sciences and other Chinese institutions have discovered PSR J1856–0039, a double neutron star (DNS) system with the lowest combined mass measured to date. Utilizing the Five-hundred-meter Aperture Spherical radio Telescope (FAST) in China, their findings, published in Physical Review Letters, confirm the system's shrinking orbit aligns with Einstein's theory of general relativity.

The system, first detected on May 4, 2020, has an orbital period of 2.36 hours, making it the second shortest known among confirmed DNS systems. Researchers observed PSR J1856−0039 in 17 sessions between 2020 and 2025, collecting 253 measurements of pulse arrival times. These precise observations allowed for the measurement of three post-Keplerian orbital parameters, including the orbital period derivative and Einstein delay.

Co-author JinLin Han noted that the system ranks second among confirmed DNS systems for its strong relativistic effects, offering high potential for detecting the Lense–Thirring (frame-dragging) effect. The low total mass suggests its merger, estimated in approximately 82 million years, will likely produce a massive neutron star rather than a black hole, providing unique insight into ultradense matter. The team plans continued monitoring to further explore relativistic effects.

What to watch: Continued observations of PSR J1856–0039 for Lense–Thirring effect.

Editor's note: The draft is accurate and covers the essential technical and mission details provided in the source.

This article is AI-generated and fact-gated. Original reporting: Phys.org