NRAO News reports on a new study in which astronomers have detected radio signals from a rare type of stellar explosion for the first time.
The discovery was made using the U.S. National Science Foundation Very Large Array (NSF VLA) and focuses on a Type Ibn supernova, an uncommon event where a star explodes into helium-rich material released before its death.
The supernova, named SN 2023fyq, was observed over 18 months, allowing researchers to study conditions around the star in the years leading up to the explosion.
Type Ibn supernovae are difficult to study because they are rare and fade quickly in visible light. Until now, information about the material surrounding them has come mostly from optical data.
Different views were revealed by radio observations showing the quantity of material the star lost and the time when that loss took place.
The star apparently threw out a great deal of helium-rich gas very shortly before the explosion, and a nearby companion star was the factor that made it happen.
Radio telescopes can also be employed to capture such fleeting and challenging-to-observe phenomena in space, as demonstrated by this work. The findings pave the way for subsequent radio explorations of similar explosions and advance the models of the stellar lifecycle.
Radio observations trace the final years before the explosion
The NSF VLA allowed astronomers to detect radio waves produced when material from the supernova slammed into gas surrounding the star. This gas was rich in helium and had been released years before the explosion.
By tracking the radio signal, researchers were able to measure the density and extent of this material and reconstruct a timeline of mass loss.
“We captured a rare, first-ever radio signal from a star exploding into helium-rich gas it shed shortly before the blast,” said Raphael Baer-Way, a graduate student at the University of Virginia and lead investigator on the study.
The radio data showed that the star experienced a strong increase in mass loss in the final years before it exploded.
Astronomers estimate that the star lost material at a rate of up to 0.4 percent of the Sun’s mass per year during this period. According to the research team, this level of mass loss is consistent with stars in close binary systems. “Radio observations allowed us to view the final decade of the star’s life before the demise,” Baer-Way added.
The study also combined radio and X-ray data to confirm that the material was released between about 0.7 and 3 years before the explosion. These measurements provide direct evidence of how conditions around a star change shortly before it becomes a supernova.
Binary systems and future radio studies of supernovae
The results support the idea that Type Ibn supernovae are linked to interactions between two closely orbiting stars. In this case, the exploding star likely had a compact companion that pulled material away over time, forming a dense disk of gas around the system.
When the explosion occurred, the fast-moving debris collided with this disk, producing the radio emission detected by the VLA.
“Our study probes the material ejected years before the explosion,” said A.J. Nayana of the University of California, Berkeley, a co-lead investigator. “It reveals that the star underwent an intense phase of mass loss in the final years of its life.”
This helps explain why Type Ibn supernovae show strong signs of interaction with nearby material.
Another researcher, Wynn Jacobson-Galan of Caltech, noted the broader impact of the work. “This study has opened up a new way to constrain the end points of certain massive stars,” he said, pointing to the value of regular radio follow-up observations.
The discovery shows that radio telescopes can capture information not accessible at other wavelengths. Future surveys using instruments like the VLA and GMRT may detect more events like SN 2023fyq, improving understanding of rare supernova types and the role of binary systems in stellar death.
Stay tuned for more updates.