What are delta Scuti stars and how did the scientists figure out their rhythm?
"Previously we were finding too many jumbled up notes to understand these pulsating stars properly", he said. "TESS has shown us that's not true for all of them".
Astronomers have measured the brightness of several thousand pulsating stars, identifying the regular rhythms in 60 the most striking of them.
Sound waves travel through a star's interior at speeds that change with depth, and they all combine into pulsation patterns at the star's surface. The so-called delta (δ) Scuti stars present seemingly random spectra of pulsation overtones, making it very hard to interpret the pulsations to glean clues about their internal structures. Data objects 1.5-2.5 times the mass of the Sun. Since then, astronomers have identified thousands more like Delta Scuti, many with NASA's Kepler space telescope, another planet-hunting mission that operated from 2009 to 2018. When studying the pulsations of this class of stars, astronomers had previously detected many pulsations, but had been unable to determine any clear patterns. TESS monitors large swaths of the sky for 27 days at a time, taking one full image every 30 minutes with each of its four cameras.
The data that came from NASA's TESS enabled astronomers to get past the noise of the universe and observe patterns and a sense of order within the internal sounds of stars. Those changes can happen in minutes.More news: Kids' COVID-Linked Ailment Is Not Your Typical Kawasaki Disease
"From here we had to cut through the noise, leaving us with the clear patterns of the 60 stars identified in the study".
"This really is a breakthrough".
"Asteroseismology is a powerful tool by which we can understand a broad range of stars", Professor Bedding said.
From these measurements we can glean a much more accurate idea about the age and mass of the star.
The team also found that a number of the stars appeared to pulse at frequencies that harmonized with other nearby stars, the first time anyone has documented the phenomenon with Delta Scuti stars. These stars not only expand and contract, maintaining a spherical shape (radial pulsation), but also occasionally become elongated (predelnye ripple) that zahumlje rhythm changes in brightness. Others occur as opposite hemispheres alternatively expand and contract.More news: Sadiq Khan: TfL services will be cut without immediate Government grant
However the sample of 60 stars observed here are all younger than roughly 500 million year, many of them less than 200 years - in comparison the Sun is 4.6 billion years old. Bedding's team used the TESS observations to create an asteroseismic model of HD 31901 that supports the younger age.
"The signals from these stars have been a mystery for over a hundred years", said Daniel Huber, study co-author and assistant professor at the University of Hawaii's Institute for Astronomy. The pulsations occur more rapidly in the fledgling stars. That can shake up the pulsation patterns and make them hard to interpret.
Another factor may be TESS's viewing angle. The team's TESS data set included around 1,000 Delta Scuti stars, which means that some of them, by chance, must be viewed close to pole-on. "Now we can detect structure, more like listening to nice chords being played on the piano".
"Stars are like a musical instrument", Professor Bedding said.
For its primary mission that lasted two years, TESS was expected to find over 20,000 transiting exoplanets.More news: 'Scarface' Reboot Movie Will Be Directed by Luca Guadagnino