Scientists measure the distance of stars through their “music”

A team of astronomers used astronomy, the study of stellar oscillations, to precisely measure the distance of stars from Earth.

Their research examined thousands of stars and verified measurements made during the Gaia mission to study the nearby universe.

For most of us, they are the countless bright spots in the night sky all Stars.

But in fact, some of these points They are distant planets and suns Or even entire galaxies located billions of light-years away. What you look at depends on how far you are from Earth.

This is why measuring the precise distance of celestial objects is an important goal for astronomers One of the biggest challenges They are currently facing it.

With this goal in mind, the European Space Agency launched the Gaia mission ten years ago. The data collected by the Gaia satellite opens a window into the nearby universe, providing astronomical measurements – such as the position, distance from Earth and motion – of nearly two billion stars.

At EPFL (École Polytechnique Fédérale de Lausanne, Switzerland), the research group “Candlesticks and Standard Distances”, led by Richard AndersonIt aims to measure the current expansion of the universe and Gaia is considered a valuable tool.

“Gaia Increase by a factor of 10,000 “The number of stars whose variances are being measured, thanks to the huge increase in resolution over its predecessor, the European Space Agency's Hipparcos mission.”

Currently, scientists use Parallax to calculate distance Who are the stars. This method consists of measuring parallax angles, with the help of a satellite, through a form of triangulation between Gaia's position in space, the Sun and the star in question.

The farther away If it is a star, the measurement is more difficult, because the parallax is smaller the distance increases.

Despite Gaia's tremendous success, measuring parallax is complex and there are small systematic effects that must be examined and corrected for Gaia's parallax to reach its full potential.

This is what scientists from EPFL and the University of Bologna in Italy have been working on, through calculations conducted in More than 12,000 giant stars Flashing Red – The largest sample and most accurate measurements to date.

“We measured Gaia's parallaxes by comparing the parallaxes reported by the satellite with the parallaxes of the same stars that we determined using stellar seismology,” he says. Sania Khana scientist in Anderson's research group and lead author of the study published In astronomy and astrophysics.

Stellar earthquakes

In the same way that geologists study the Earth's structure through earthquakes, astronomers use them Astroseismologyspecifically the vibrations and oscillations of stars, to obtain information about their physical properties.

Stellar oscillations are measured as follows: Small differences in intensity Light is translated into sound waves, resulting in the frequency spectrum of these oscillations.

“The frequency spectrum allows us to determine how far away the star is, which allows us to get asteroid parallax variations,” Khan says. “In our study,We hear the “music” of a large number of stars -Some of them are 15,000 light-years away!

To convert sounds into distance measurements, the research team started from a simple fact. The speed at which sound waves propagate through space It depends on temperature and density From inside the star.

“By analyzing the frequency spectrum of stellar oscillations, we can estimate the size of a star, just as we can determine the size of a musical instrument by the type of sound it makes — think of the difference in tone between a guitar and a cello,” she says. Andrea Miglioprofessor at the Department of Physics and Astronomy at the University of Bologna and third author of the study.

Advanced analytics

After calculating the size of the star, astronomers determined its brightness and compared it with the brightness observed on Earth.

They then linked this information to temperature and chemical composition readings obtained through spectroscopy and subjected this data to sophisticated analyses. Calculate the distance to the star.

Finally, astronomers compared the parallax obtained through this process with that reported by Gaia, to verify the accuracy of the satellite's measurements.

“Astroseismology.” This is the only way to verify accuracy “The view of Gaia varies across the entire sky, for low- and high-density stars,” says Anderson. The future of this field is bright, as Khan highlights:

Space missions such as TESS and PLATO, which aim to discover and study exoplanets, will use astroseismology and provide the necessary data sets across increasingly wider regions of the sky.

“Methods like ours will play a crucial role in improving Gaia's parallax measurements, which will help us determine our place in the universe and benefit a number of subfields of astronomy and astrophysics,” Anderson concludes.