Scientists Use Stellar 'Quakes' to Uncover Secrets of Stars' Inner Workings

Scientists Study Stellar 'Quakes' to Reveal the Hidden Interiors of Stars

Stars don't simply shine — they hum with subtle vibrations that reveal much about their inner structures. These "stellar quakes," akin to seismic activity on Earth, provide researchers with valuable insights into the hidden layers of stars. By observing the ripples of gas on a star's surface, scientists can explore the turbulent outer layers, known as the convective envelope, where hot gas rises, cools, and sinks in a continuous cycle of energy transfer.

"Stellar quakes occur in stars with bubbling outer layers, similar to boiling water," explained Claudia Reyes, who conducted the research as a Ph.D. student at the University of New South Wales. "As these bubbles of hot gas rise and burst, they send waves through the entire star, causing it to vibrate in specific patterns. These vibrations, known as acoustic oscillations, can be detected by measuring slight variations in the star's brightness."

Just as seismic waves help scientists study Earth's interior, these stellar quakes provide a method for probing the internal structure of stars. "Each star has its own unique resonant frequencies, determined by its internal structure and physical properties," said Reyes, now a postdoctoral fellow at the Australian National University. "Larger stars produce deeper, slower vibrations, while smaller stars vibrate at higher frequencies."

One of the critical tools for understanding these vibrations is "small frequency spacing," a feature that helps scientists estimate the amount of hydrogen fuel a star, like the Sun, still has. The fusion of hydrogen into helium at a star's core is what fuels its energy and drives its lifecycle. By studying this, scientists can gain insights into a star's age and evolution.

Stars undergo complex changes over billions of years. While it is difficult to track the aging process of individual stars, scientists can study star clusters — groups of stars that formed at the same time and share similar compositions. "More massive stars evolve faster than smaller ones, so by examining star clusters, we can observe a broad range of evolutionary stages," Reyes explained.

Reyes and her team focused on studying stellar quakes in 27 stars from the open cluster Messier 67 (M67), a group of over 500 stars. M67 is one of the oldest known open clusters, with an age similar to the Sun’s, and includes about 100 Sun-like stars, along with many red giants and white dwarfs.

“M67 was of particular interest because it has a chemical composition similar to the Sun's," Reyes said. "This allowed us to probe the fundamental physics deep within these stars, under extreme conditions, and build more reliable models of star evolution." These findings will help scientists better predict how stars like the Sun will evolve as they age, offering a more accurate understanding of stellar life cycles.

Through the study of stellar quakes, scientists are gaining unprecedented access to the internal workings of stars, helping to unlock the mysteries of how stars evolve over time.

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