Astronomers have picked up the first-ever radio signals from aType Ibn supernova, a rare kind of stellar explosion tied to massive stars that shed helium-rich material shortly before they die. The event, SN 2023fyq, is now giving scientists an unusually direct look at what a star was doing in its final years, not just the explosion itself.
Type Ibn supernovae are still pretty mysterious because they don’t show up often and are usually only observed after the fact. They come from massive stars that lose a lot of helium-rich gas right before dying, building up a dense cloud around them. Researchers at the University of Virginia College and Graduate School of Arts & Sciences point out that this material ends up shaping how the explosion looks and evolves, even though it’s created before the star actually blows up.
Most of what astronomers knew before this came from optical light, which mainly shows the aftermath of the explosion. That’s useful, but it doesn’t really reveal what the star was doing in its final years. The new study, published in The Astrophysical Journal Letters, switches things up by using radio waves, which can trace the interaction between the expanding debris and the gas surrounding the star.
Radio Waves Reveal the Hidden Surroundings
The signal was detected with the National Science Foundation’s Very Large Array in New Mexico. Over about 18 months, researchers tracked faint radio emission from SN 2023fyq. The data, reported in The Astrophysical Journal Letters, covers frequencies from 3 to 35 GHz and spans from 58 to 525 days after the explosion.
What’s producing the signal is basically a collision. The supernova’s shockwave is slamming into helium-rich material that the star had already shed. That impact generatesradio waves, which in turn map out how much material is sitting around the star and where it’s distributed.
Raphael Baer-Way, the lead author and a Ph.D. student at the University of Virginia, described it in a release as a way to look back in time.
“We were able to use radio observations to ‘view’ the final decade of the star’s life before the explosion,” he said, explaining that the strongest clues come from the last few years when the star was losing mass more aggressively.
Rebuilding The Star’s Final Years
The radio light patterns suggest the star didn’t just lose a steady wind of material, it went through a more intense phase near the end. The research team said that the most active period likely happened in the last five years before the explosion. Baer-Way compared the data to something like a reconstruction of the star’s final timeline.
“We were able to use radio observations to ‘view’ the final decade of the star’s life before the explosion. It’s like a time machine into those last important years, especially the final five when the star was losing mass intensely,” he stated.
The key idea is simple physics: denser gas produces stronger radio emission when it is hit by the blast wave. Researchers are studying how the explosion interacts with everything the star left behind.
A Possible Binary Star Behind The Chaos
One of the big questions is why the star lost so much material so quickly. The team at the University of Virginia thinks a binary companion might be involved. Baer-Way pointed out that it’s hard to explain this level of mass loss with a single star acting alone. A nearby companion could have pulled or disrupted the outer layers through gravity, speeding up how fast the star shed material before it went supernova.
The study also highlights something broader: radio astronomy is becoming a bigger deal for studying stellar deaths. Maryam Modjaz, professor at the University of Virginia and co-author on the work, said that:
“Raphael’s paper has opened a new window to the universe for studying these rare, but crucial supernovae, by revealing that we must point our radio telescopes much earlier than previously assumed to capture their fleeting radio signals.”
