In a groundbreaking discovery, astronomers have observed a neutron star spinning at an astonishing rate of 716 rotations per second, making it one of the fastest-spinning stars ever recorded. Located about 26,000 light-years from Earth in the globular cluster NGC 6624, this neutron star resides in the binary system 4U 1820-30 within the constellation of Sagittarius.
The extraordinary discovery was made using data collected by NASA’s Neutron star Interior Composition Explorer (NICER), which is stationed aboard the International Space Station (ISS). In addition to its rapid spin, the neutron star’s surface is also marked by explosive thermonuclear bursts, similar to atomic detonations, adding to its remarkable characteristics.
Between 2017 and 2021, scientists from DTU Space monitored the star’s activity and identified 15 thermonuclear bursts, one of which exhibited a distinct signature confirming the star’s spin rate of 716 Hz. This finding aligns with observations of another fast-spinning neutron star, PSR J1748–2446. “During these bursts, the neutron star becomes up to 100,000 times brighter than the Sun, releasing an immense amount of energy,” explained Jerome Chenevez of DTU Space.
Neutron stars, the remnants of massive stars that have exhausted their nuclear fuel, are known for their extreme densities and rapid spins. When a star undergoes a supernova explosion, its core collapses to a diameter of about 20 kilometers, while maintaining a mass up to twice that of the Sun. This collapse accelerates the star’s rotation, a phenomenon driven by angular momentum conservation.
The 4U 1820-30 system is particularly intriguing because it contains a white dwarf that orbits the neutron star every 11 minutes—the shortest known orbital period for any binary star system. This rapid orbit facilitates frequent matter transfers, which in turn fuel the thermonuclear reactions occurring on the neutron star’s surface.
These recent discoveries provide a rare and valuable insight into the lifecycle of neutron stars and the dynamic processes within binary systems, shedding light on the fascinating and extreme nature of these stellar remnants.
