The oscillations of stars caused by “stellar earthquakes” may hold the key to unraveling their evolution and the history of our galaxy. Scientists analyzing data from the Kepler Space Telescope have found that vibrations from red giants in the M67 star cluster reveal unexpected details about their inner world. The results of the study are published in the journal Nature.
Stellar earthquakes: music of the interior
Most stars, including the Sun, constantly “shake” due to processes similar to boiling water. Hot bubbles of gas rise from the depths, explode at the surface, and generate waves that make the star vibrate at resonant frequencies. These fluctuations, visible as changes in brightness, resemble the unique melody of each star. By studying them, astronomers obtain data on the mass, age, and chemical composition of the luminaries.
Stuck melody
The M67 cluster (NGC 2682) is located 3,000 light-years away. It is an ideal laboratory: its stars have solar chemical composition and formed almost simultaneously. Researchers used data from the Kepler telescope’s K2 mission to trace how stars evolve during the red giant phase. It turned out that their resonant frequencies do not just reflect size, but also underlying changes in thermonuclear processes.
The main surprise of the study is the discovery of a “halt” in the change in frequencies. When the outer layers of the star, where hydrogen combustion takes place, reach 80% of its mass, their oscillations suddenly stabilize. It’s like a record looping on a single note. The reason is a sharp change in the speed of sound at the boundary between the core and the shell of the star. This “pause” allows the mass, age and chemical composition of the giants to be accurately determined.
From stars to galactic history
“Stellar Symphonies” is not just about physics. Each star has the mark of the environment of its birth. The Milky Way formed by absorbing smaller galaxies, and accurate data on the ages of stars will help recreate this process. For example, M67 gives an idea of the Sun’s future: in billions of years, our star will also swell to a red giant, and its oscillations will become part of the galactic “score”.
The study surpasses previous notions: resonant frequencies were much more informative than thought. Now scientists can “learn to listen” to stars in a new way by analyzing existing data from telescopes. This opens the way to creating a more detailed map of the Milky Way’s life – one note of a stellar symphony at a time.
Stellar earthquakes, as it turns out, are not just spectacular phenomena. They have become a scientific sonographer, allowing us to look into the deepest layers of stars and decipher the history of the galaxy. And if previously we were only trying to distinguish individual notes, now we have the score for an entire space opera.
We previously reported on how a giant star appeared to be covered in sun-sized spots.
According to Science Alert
