Researchers in the Department of Physics & Astronomy at Texas Tech University recently used audio to represent the spectacular explosion of a star in deep space while also delving into the data to better understand how the phenomenon unfolded.
The explosion of NovaV612 Scuti, also known as ASSASSN-17hx, was discovered in 2017 and observed by astronomers around the world. Those observations produced data allowing researchers to study how the eruption changed over time. At Texas Tech the work has been led by undergraduate student Pragati Acharya under the guidance of Assistant Professor Elias Aydi .
By transforming the nova's changing light into audio, the team has added a new dimension to understanding how the explosion unfolded.
"This sonification allows people not only to see the changing brightness of the explosion, but also to hear its evolution," Aydi said. "In other words, we can now offer audiences a way to experience what a stellar explosion might 'sound' like when astronomical data are translated into audio."
The findings have been accepted for publication in the journal Monthly Notices of the Royal Astronomical Society (Oxford Press).
A nova occurs when a dense stellar remnant, known as a white dwarf, pulls material from a companion star. As that material builds up on the white dwarf's surface, it can trigger a sudden thermonuclear explosion, causing the system to brighten dramatically.
Aydi explained that although scientists have long studied these explosions, recent discoveries have changed how researchers understand these event
These discoveries led astronomers to explore how novae could produce such energetic radiation. One explanation centers on shock waves. During a nova eruption, gas can be ejected at different speeds. Later faster-moving material may collide with gas ejected earlier, creating powerful shocks.
The shocks also heat the surrounding gas, causing it to radiate at visible wavelengths. Recent studies have shown that much of the visible light typically observed from novae, long thought to come primarily from nuclear reactions on the surface of the white dwarf, may instead originate, at least in part, from the shock-heated gas.
To investigate the eruption, the researchers used spectroscopy, a technique that separates light into different wavelengths, much like spreading light into the colors of a rainbow. This allows astronomers to measure how strongly the object emits at different wavelengths and to track the motion of gas during the explosion.
Astronomers around the world observed V612 Scuti using spectroscopy and shared their data with the broader scientific community. The Texas Tech team used those observations to examine when the brightness jumps occurred, what caused them and how the gas moved during the eruption.
Aydi said the team found evidence that new ejections occurred with each jump in the light curve. By studying shifts in the spectra, they were also able to calculate the velocity of the material. Over several months of observations, they found that the gas increased significantly in velocity with each major jump.
The team decided to take the analysis a step farther.
"We had high-resolution spectra, which measure intensity versus frequency, and we said, 'We can actually convert this extensive set of data into an equivalent of sound.'" Aydi said. "So, we converted the intensity of light into sound pitch and the frequency of light into frequency of sound."
Acharya carried out much of the data analysis, including creating the figures for the paper and producing the sonification. She said she gained valuable experience in coding, spectroscopy and astronomical data analysis.
"I realized how it works bit by bit, code by code, and what the sonification script actually does," she said. "When I did it all by myself and changed the wavelengths into frequencies and produced a sound, it felt like the best thing I had ever done, and it's something I will never forget."
