Universal clues found in the musical melodies of 'starquakes'

In astronomy, a faint hum often carries hidden information about our universe. Some stars pulse with subtle fluctuations, and those signals can tell us a lot about how the Milky Way was formed. A new study links these gentle waves, or starquakes, to the complex processes taking place inside stars.

This connection offers a richer picture of stellar aging and how matter that is recycled by stars shapes our galaxy’s overall design.

Starquakes reveal stellar interiors

Study lead author Dr. Claudia Reyes from The Australian National University and UNSW Sydney refers to these pulses as musical notes that reflect a star’s true character.

Researchers measure tiny changes in brightness and convert them into frequencies for closer inspection.

“Starquakes occur in certain stars, leading to a continuous cycle of brightening and dimming. By carefully observing these tiny fluctuations in brightness, we can listen to a star’s musical rhythm,” explained Dr. Reyes.

Understanding red giant stars – the basics

Red giant stars are what happen when a star like our Sun runs low on fuel. After spending millions or even billions of years burning hydrogen in its core, the star starts to run out.

When that happens, gravity begins to crush the core, and the outer layers puff outward.

The star swells up – sometimes hundreds of times larger than its original size – and cools down on the surface, which gives it that reddish glow. It looks calm and glowing, but inside, it’s going through serious changes.

These stars don’t just sit around getting bigger, though. Inside, the core begins fusing helium instead of hydrogen, and the star can go through a few wild phases before it reaches the end of the line.

Some red giants eventually shed their outer layers, forming beautiful clouds of gas called planetary nebulae. What’s left behind is a tiny, dense white dwarf – the star’s former core, still glowing with leftover heat.

Starquakes help measure age and fusion

Experts rely on asteroseismology to interpret these oscillations, which reflect the density and temperature layers in a star.

This method can expose details about stellar mass, age, and even the fusion processes occurring deep within.

Solar-type stars vibrate in distinct ways depending on their core conditions and chemical makeup.

By mapping these vibrations, astronomers can place each star on a timeline that reveals its past and hints at potential changes in the future.

Role of open cluster M67

A team focused on open cluster M67, a stellar gathering believed to have formed from the same giant molecular cloud.

This cluster is notable because its stars share similar ages and elements, making comparisons more reliable.

Investigators looked at subgiant and red giant stars in M67 to capture their shifts in brightness frequencies.

They spotted a short window when the usual progression of frequencies halted before continuing on a new track.

New clues about how stars change

This pause, sometimes referred to as a plateau, highlights a significant adjustment in the star’s internal layers.

It suggests that certain fusion zones or structural layers might expand or contract in ways that change the star’s musical signature.

That insight opens a new door to measuring star ages more precisely. A small shift in frequency can indicate a major transition inside a star, and that transition marks an important milestone in its life cycle.

Starquake timing and galaxy growth

Stars funnel heavy elements into interstellar space once they move beyond certain phases of nuclear burning.

These elements enrich the raw material that shapes future stars, planets, and even life-supporting systems.

Precise timelines for when stars start and stop various fusion processes help astronomers see the bigger picture of galactic formation.

They can map the chemical trails that lead from one generation of stars to the next, revealing how the Milky Way acquired its current structure.

A window into the Sun’s future

Stars in M67 are sometimes compared to our Sun, but they are in later stages of development.

By watching their changes, scientists can predict how the Sun’s energy-producing layers might behave many millions of years from now.

Observing the starquake signals from these older siblings can warn us about potential instabilities or shifts in solar output.

It also reassures us that certain phases will unfold gradually, offering enough lead time to understand any impact on our planetary neighborhood.

Starquakes and stellar science

The plateau discovery demonstrates how subtle features in starquake data can refine age calculations.

This improvement benefits large-scale surveys that aim to chart our galaxy’s past by examining countless stars at various evolutionary stages.

Scientists are now combining data from observatories worldwide to see if similar patterns arise in other clusters.

Each cluster provides a small piece of a larger puzzle, and collectively they help us trace the path of star formation and chemical enrichment across cosmic distances.

The study is published in Nature.

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