In 1181, ancient astronomers recorded a naked-eye supernova. Modern astronomers categorized the explosion as a stellar death. Almost 900 years later, University of Notre Dame researchers studied the remnant and found that an active star remains.
The research on the star, WD J005311, published in the Astrophysical Journal, proved that it did not follow the path most stars do when ending their life cycle. The project was led by Professor of Physics and Astronomy Peter Garnavich, who began his research after reading about the star in a separate astronomical journal. He and collaborators discovered three key findings about the star.
First, J005311 has stellar winds that exhibit extreme variability, with spectra lines, as described by Garnavich, changing at extreme levels.
Graduate researcher C. Alexander Thomas, a student in Garnavich’s lab in 2021, took images of the stars and converted those into spectra. By taking pictures of the object and “smearing” the light into colors on the detector, the rapid changes in the star’s wind were recorded. Using this method, researchers found the star to be boiling like hot water on a stove.
J005311 triggered Garnavich’s interest because it did not follow the pathway that many stars do when ending their life cycle. Stars like our Sun shed their outer layers, briefly form a planetary nebula, and leave behind a dense core called a white dwarf. When the star has a companion, the two often spiral inward, colliding to create a huge explosion known as a supernova. That process destroys the star. For J005311, the star was not completely destroyed. Rather, it left behind an unstable remnant.
The second new discovery is a pair of bright peaks of light, or emission lines, which suggest material is being ejected in a rapidly rotating plane from the star. Associate Professor of Practice in Physics and Astronomy Lara Arielle Phillips worked on researching the magnetic fields surrounding the star. The original hypothesis, according to Phillips, was extremely high magnetic fields due to the star being a white dwarf remnant. The team later discovered the material was released in a disk, but could not confirm the strong magnetic fields.
"We think [the star is] blowing off this kind of outer layer, this kind of outer shell at about 16,000 kilometers per second, or... about 5% the speed of light... which is an absurd wind," said Thomas.
Additionally, the researchers analyzed past Hubble Space Telescope data in the ultraviolet, leading to their discovery of the star's regular variations. Most stars that spin at such high speeds would have various speeds of spinning at different, irregular times. J005311, the variation is quite regular at ultraviolet wavelengths, varying on an hour-long timescale.
Thomas’ research has shifted since 2021 when observations on J005311 were recorded, and he now focuses on planets beyond our solar system. The two additional authors on this paper are Charlotte Wood (ND PhD 2023), Assistant Professor in the Physics Department at North Carolina Agricultural & Technical State University, and Richard Pogge, Ohio State University College of Arts and Sciences Distinguished Professor of Astronomy and Vice Chair for Instrumentation.
Originally published by at science.nd.edu on August 07, 2026.