These data revealed the internal structures of the stars, which could help understand what’s going on in billions of stars across the universe.
This particular class of stars is known as the Delta Scuti star. They take their name from a bright star, Delta Scuti, in the constellations of the Scutum and are each about 1.5 to 2.5 times the mass of our sun.
Previously, astronomers were unable to detect the pulsations in these stars, but were unable to determine a pattern.
Pulsations are natural resonances that come from the stars, formed by trapped waves similar to those of musical instruments. These sound waves travel from within the star to create pulsation patterns on their surface. For astronomers, these appear as changes in the brightness of the star.
A pulsating mystery
S pulsating astronomers can learn the key details about them.
These back and forth movements within the stars, called oscillations, can reveal their internal mechanisms. This is called asteroseismology, which is when we learn more about stars by measuring changes in star light.
It is similar to how earthquakes allow us to study the interior of the Earth in seismology.
For example, changes in the brightness of our sun have provided astronomers with information about its temperature and chemical composition, as well as the processes that occur within it.
Asterosismology has been used to understand stars such as our sun, mass stars, red giants and white dwarfs. But so far the stars of Delta Scuti have confused scientists.
This is because while “many stars pulsate along simple chords”, the melody of the Delta Scuti stars is much more complex, said Tim Bedding, lead author of the study and professor at the University of Sydney, in a statement.
Delta Scuti’s stars rotate once or twice a day, which is much faster and about a dozen times faster than our sun. This can shake the pulse patterns and make them difficult to interpret.
“The signs of these stars have been a mystery for over a hundred years,” said Daniel Huber, co-author and assistant professor at the Astronomy Institute of the University of Hawaii. “We knew that the changes in brightness of these stars are caused by sound waves traveling inside them, but we couldn’t make any sense of it.”
The TESS mission, designed to detect exoplanets or planets outside our solar system, around nearby stars, acquires data on the brightness of the stars. When astronomers used the TESS data, they could narrow their focus on 60 Delta Scuti stars, between 60 and 1,400 light years away from Earth, with clear pulsations of brightness. These pulsed regularly at high frequency.
The TESS data had to be processed through software, designed by Daniel Hey, co-author of the study and a doctoral student at the University of Sydney.
“We needed to process all 92,000 light curves, which measure a star’s brightness over time,” Hey said in a note.
“From here we had to cut the noise, leaving ourselves with the clear patterns of the 60 stars identified in the study. Using the open source Python library, Lightkurve, we were able to process all the light curve data on my university desktop computer in a few days” .
Observations from Maunakea’s W. M. Keck Observatory in Hawaii also revealed that regular patterns came from Delta Scutti stars that rotated slower than normal, which could help explain their frequency patterns. Follow-up observations were also conducted using the global network of the Las Cumbres Observatory.
Listening to heavenly heart beats
“Previously we were finding too many confusing notes to understand these pulsating stars correctly,” Bedding said.
“It was a mess, like listening to a cat walking on a floor. The incredibly accurate data of NASA’s TESS mission allowed us to cut the noise. Now we can detect the structure, more like listening to the beautiful chords played on the plan “.
Huber likened it to “the notes of a song that finally fell into place to play a beautiful melody”.
And the pulsations of the Delta Scuti stars can reveal their mass, age and internal structure.
“Our results show that this class of stars is very young and some tend to attend free associations. They have not yet had the idea of” social distance “rules,” Bedding said.
Young stars offer astronomers a chance to see how stars evolve, as well as the formation and evolution of the planets around them – a bit like peering back into the formation of our solar system, said Eric Gaidos, co- author and professor of the School of Ocean and Earth Science and Technology of the University of Hawaii.
“Some of the stars in our sample host planets, including beta Pictoris, just 60 light years from Earth and visible to the naked eye from Australia,” said Isabel Colman, co-author and PhD student at the University of Sydney, in a statement. “The more we know about stars, the more we learn about their potential effects on their planets.”
It is a turning point for researchers and they plan to continue staring at Delta Scuti with TESS in the future. Although TESS was designed to find exoplanets, there was also hope that it could help advance asterosismology – and it has only just begun.
“We are thrilled that TESS data is used by astronomers around the world to deepen our knowledge of stellar processes,” said George Ricker, co-author of the study and TESS Principal Investigator at the Kavli Institute for Astrophysics and Space Research. of the Massachusetts Institute of Technology in Cambridge in a statement.
“The results have opened up completely new horizons to better understand an entire class of stars.”
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