Science

A starquake and a Stradivarius: Scientists "listen" for the Milky Way's age

A earthquake on a burning-hot ball of light signals just how old all of this is.

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On December 27, 2004, a blast of energy suddenly erupted 50,000 light-years from Earth. It was so powerful that it disrupted radio transmissions for a tenth of a second. The massive explosion, which released more energy than the Sun releases over 150,000 years, was likely caused by an earthquake that took place on a burning-hot ball of light.

If it had occurred within 10 lightyears from Earth, then our planet would have suffered a mass extinction, the BBC reported at the time.

The cause for that radio disruption, was, to put it simply, a “starquake.”

Scientists this week reported they have finally figured out how to answer a longstanding cosmic question — how old is the Milky Way? — by measuring the power of starquakes.

A study, published in the journal Monthly Notices of the Royal Astronomical Society used records of starquakes to measure the age of the galaxy that contains our solar system.

How old is the Milky Way? Scientists may finally have an answer.NASA

The data about starquake energy proves that asteroseismology — using starquakes to identify the internal structures of stars — is a reliable method to estimate the age of the cosmos and its material.

When does a starquake occur?

Starquakes occur when a dense star has its crust ripped wide-open, possibly when sudden changes take place in its magnetic field. The star will produce a fireball of radiation, which are some of the brightest flashes of high-energy photons ever observed.

The team of scientists behind the new study used data gathered by NASA’s Kepler space telescope, which launched in the year 2009 and recently retired in October, 2018, and observed around 530,506 stars.

They then measured the soundwaves produced by the starquakes, and the frequencies helped them identify certain characteristics of the stars— including how old they are.

"It’s a bit like identifying a violin as a Stradivarius by listening to the sound it makes

“It’s a bit like identifying a violin as a Stradivarius by listening to the sound it makes,” Dennis Stello, an associate professor at the University of New South Wales, and co-author of the study, said in a statement. “The quakes generate soundwaves inside the stars that make them ring, or vibrate.”

Antonio Stradivari examining his work. Scientists compared listening to a starquake like listening to a Stradivarius violin.Public Domain

Other studies have looked at the gas composition of stars in order to figure out their age, with the older stars having heavier elements in their makeup.

Instead of listening to the soundwaves produced by the starquakes, the team of scientists behind this new study looked at the changes in the brightness of the stars, which are caused by movements on their insides, as they undergo starquakes.

The particular stars that this new study make up the Milky Way’s thick disc. (The galaxy is made up of a thin and thick disc, much like most other spiral galaxies.) The stars in the thick disc are believed to be older than the ones formed along the thin disc, and astronomers speculate that the thick disc was formed first in the Milky Way, and ceased its star formation. The thin disc then formed shortly afterwards, and began its own star formation process.

An artist's impression of the Milky Way's thin and thick disc.NASA/JPL Caltech/R.Hurt/SSC

Therefore, the stars of the thick disc likely began popping up in the Milky Way during the galaxy’s infancy. Based on the recent findings, the age of the thick disc was estimated to be around 10 billion years old.

The Milky Way, believed to be one of the oldest galaxies of the universe, might be between 10 to 13.5 billion years old.

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