Astronomers Watch a Dormant Neutron Star Reignite After a Decade of Silence

Astronomers have watched a neutron star that had seemed “dead” come back to life, which could teach them more about one of the most powerful X-ray sources in the universe. Over the course of a decade, the neutron star P13 has gone through extreme swings in brightness and speed of rotation, with its X-ray emissions increasing by hundreds of times. These shifts, scientists say, indicate the changing manner in which gas is falling on the star. The findings help explain how ultraluminous X-ray sources reach such extreme power and why they can switch between quiet and active phases over time.

Astronomers Track Neutron Star P13's Dramatic Brightening and Spin Changes Over a Decade

According to a report based on observations published by an international research team, the neutron star P13 is located in the galaxy NGC 7793, roughly 10 million light-years distant from Earth. Astronomers followed P13 from 2011 to 2024, observing a dim phase in 2021 and a more than a hundred-fold brightening by 2024.

Neutron stars produce very high-energy X-rays as matter falls onto their surface. In P13, gas flared from magnetic poles to create glowing columns, but the brightness didn't correspond to its 0.4-second spin.

Neutron Star's Rapid Spin-Up Tied to Structural Changes in Extreme Accretion Flow

The new analysis revealed that during the rebrightening phase, the neutron star's spin-up rate doubled and stayed high for years. This close link between brightness and rotation suggests the structure of the accretion flow itself changed during the quiet period.

Detailed pulse analyses suggest the accretion column's height changed over a decade, providing key insights into supercritical accretion, where matter falls onto compact objects at extreme rates.