“Music” by Starquakes – the enormous vibrations caused by bursting gas bubbles that wavy throughout the bodies of many stars – can reveal much more information about the history of the stars and their internal functions than scientists thought.
in New research published in Natureanalysed the frequency signatures of Starcasts across a wide range of giant stars in the M67 star cluster, almost 3,000 light years from Earth.
During most journeys traveling through huge stages of the star lifecycle using observations from the K2 missions in Kepler Space Telescope, it has been a rare opportunity to track star evolution.
In doing so, we found that when the outer layer of turbulence reaches deep and sensitive areas, these stars get stuck “playing the same part of the song.”
This discovery reveals new ways to understand the history of stars and the history of the entire galaxy.
Starquakes sound
On most stars (like our sun), which have a foaming outer layer like boiling water, the star occurs. Hot gas bubbles rise and burst on the surface, sending ripples across the star that causes them to vibrate in a certain way.
By looking for subtle variations in star brightness, these vibrations occurring at specific “resonant frequencies.” By studying the frequency of each star in a group called clusters, we can adjust it The unique “songs” of the cluster.
Our research challenges previous assumptions about the frequency of giant stars resonance and reveals that it offers deeper insights into stellar interiors than previously thought. Furthermore, our research has opened up new ways to decipher the history of our galaxy.
Star cluster melody
Astronomers have long tried to understand how our Sun-like stars evolve over time.
One of the best ways to do this is to study the clusters. This is a group of stars that are formed together and share the same age and composition. The cluster, called the M67, attracts a lot of attention as it contains many stars with chemical compositions similar to the sun.
Starcues reveal what lies beneath the surface of the stars, so that earthquakes help us study the interior of the Earth. Each star “sings” a melody at a frequency determined by its internal structure and physical properties.
Larger stars produce deeper and slower vibrations, while smaller stars produce higher pitches. And you never play a note with just one star. Each one resonates with a full-spectrum sound from within it.
Amazing Signature
Among important frequency signatures are what are called small intervals. This is because the resonance frequencies are very close. On young stars such as the Sun, this signature can provide clues as to the amount of hydrogen that the star still remains to burn at its core.
With the Red Giants, things are different. These old stars have exhausted all the hydrogen in their core and are now inert.
However, hydrogen fusion continues in the shell surrounding the core. It has long been assumed that such small spacing of stars provides little new information.
A stalled note
When measuring the small spacing of stars in the M67, I was surprised to see that they revealed changes in the star’s internal fusion region.
The interval increased as the hydrogen combustion shell thickened. They shrunk as the shell moved inwards.
Then we found something else that was unexpected. At certain stages, small intervals stopped. It was like a record that skips notes.
We discovered that this stall appears at certain stages in the life of a giant star. It is when its outer envelope, the “boiling” layer that transports heat, grows very deeply, accounting for about 80% of the star’s mass. At this point, the inner boundary of the envelope reaches a very sensitive area of the star.
This boundary is very turbulent, causing a sudden shift in the speed of sound. And that sudden change affects the way sound waves pass through the stars. It was also found that stall frequency is clearly determined by star mass and chemical composition.
This gives us a new way to identify stars during this phase and estimate age with improved accuracy.
Galaxy history
Stars are like a fossil record. They can connect our galaxy stories by carrying traces of the environment they formed and studying them.
The Milky Way grew by merging with smaller galaxies and forming stars at different times in different regions. Higher age estimates across Galaxy can help reconstruct this history in greater detail.
Clusters like the M67 also offer a glimpse into our own future of the sun, providing insight into the changes we experience over billions of years.
This discovery provides new tools and new reasons to revisit the data you already have. Years of earthquake observations from the whole Milky Way allow us to return to these stars and “listen” again. This time I know what to ask.
Claudia ReyesPostdoctoral Fellow, Research School Astronomy & Astrophysics, Australian National University
This article has been republished conversation Under the Creative Commons license. Please read Original article.
