Astronomers Observe Neutron Star P13 Revive After Decade of Dormancy

A team of astronomers has documented the awakening of a neutron star known as P13, located in the galaxy NGC 7793, approximately 10 million light-years from Earth. This discovery, reported on December 14, 2025, reveals that P13 has undergone significant changes over the past decade, characterized by fluctuations in its X-ray luminosity and rotation rate, which suggest a complex evolution of its accretion structure.

The research, led by scientists from Ehime University, focused on the phenomenon known as supercritical accretion, where an immense amount of gas falls onto a neutron star, creating an accretion column at its magnetic poles. This process generates intense electromagnetic waves, particularly X-rays. The brightness of P13 varied dramatically, with luminosity increasing and decreasing by factors of hundreds, highlighting the dynamic nature of this celestial object.

From 2011 to 2024, the research team analyzed archival data from several observatories, including XMM-Newton, Chandra, NuSTAR, and NICER. They observed that P13 entered a faint phase in 2021, followed by a resurgence in brightness starting in 2022. By 2024, the star’s luminosity surged to levels more than two orders of magnitude higher than in 2021.

Understanding the Relationship Between Accretion and Pulsation

The study found that during the rebrightening phase in 2022, the rotation rate of P13 accelerated significantly, doubling its previous rate. This change, sustained through 2024, indicates a potential link between X-ray luminosity and rotation velocity. The findings suggest that the accretion system underwent notable alterations during the faint phase, possibly influencing the neutron star’s behavior.

Astronomers noted that as gas accumulates on P13, it creates a column that emits coherent X-ray pulsations. Previous research established that P13 rotates with a period of 0.4 seconds. However, the relationship between its rotation speed and luminosity remained unclear until this recent investigation. The data collected over the decade provides new insights into how ultraluminous X-ray sources achieve their extraordinary power.

The research team proposed that the height of the accretion column fluctuated with the observed changes in luminosity, contributing crucial clues to the understanding of supercritical accretion mechanisms. Such insights are essential for unraveling the complexities of neutron stars and the processes that govern their evolution.

This work not only enhances the knowledge of P13 but also contributes to broader astrophysical discussions regarding the behavior of neutron stars and similar compact objects. As astronomers continue to monitor P13, the ongoing research may yield further revelations about the intricate dynamics of these powerful cosmic entities.