Scientists have discovered one of the fastest spinning neutron stars, located at a distance of 27,400 light years. This neutron star, part of the 4U 1820-30 binary system, rotates around its axis at an astonishing rate of 716 revolutions per second, setting a new record for these celestial objects. Previously, only the PSR J1748-2446AD pulsar exhibited similar rotation speeds.
The Astrophysics team led by Gaurava Jiaval from the Technical University of Denmark believes that this finding confirms the theoretical limit of neutron star rotation speed, which is estimated to be around 730 revolutions per second. By studying thermonuclear explosions in the 4U 1820-30 system, scientists observed unusual fluctuations indicating the behavior of the stars within the system.
Neutron stars are formed after the collapse of massive stars with a mass between 8 to 30 times that of the sun. When these stars deplete their nuclear fuel, their core collapses, giving rise to a neutron star, a compact object of incredibly high density. Depending on their characteristics, these stars may be classified as magnetars if they have a strong magnetic field, or pulsars if they emit radio waves from their poles, creating a pulsing effect.
The 4U 1820-30 system, known since the 1980s, consists of a neutron star and a white dwarf in the constellation Sagittarius, orbiting each other every 11.4 minutes. Due to their close proximity, the neutron star accretes matter from the white dwarf, leading to thermonuclear explosions on its surface. These explosions cause the neutron star to become remarkably brighter, releasing vast amounts of energy.
Between 2017 and 2022, researchers observed 15 such explosions using the Nicer telescope aboard the ISS. During one of the analyses, they detected a signal with a frequency of 716 Hertz, indicative of the neutron star’s rotation at the time of the explosion. This suggests that the 4U 1820-30 system houses the fastest known nuclear pulsar, achieving such high speeds due to thermonuclear processes on its surface.
Further observations are required to confirm this hypothesis. If validated, this discovery will open up new avenues for studying the extreme conditions present on neutron stars and their maximum