What are stellar earthquakes that make the stars move

Gaia aims to build the largest and most accurate 3D spatial catalog ever made of the observable universe / Ship:ESA/ATG medialab/Milky Way:ESA/Gaia/DPAC/IGO/A. Moitinho

In 2013 the European Space Agency (ESA), launched a unique space mission: Gaia Space Observatory, a spacecraft designed specifically for astrometry – the science of measuring the positions, distances, and motions of stars with a precision never seen before.

Scientists claim that the mission aims to build the largest and most accurate 3D spatial catalog ever made of the observable universe, with a total of approximately two billion astronomical objects, mainly stars, but also planets, comets, asteroids and quasars, among other fascinating objects from the vastness of space.

This week, ESA released a new update of data collected by Gaia in the last three years, after having observed 10 million stars and space objects, which caused the publication of several scientific papers on some of the discoveries made. This data set has become the largest catalog to date of binary stars, thousands of objects in the solar system, such as asteroids and the moons of planets, and millions of galaxies and quasars located outside the Milky Way.

Map of the Milky Way, photographed by ESA
Map of the Milky Way, photographed by ESA

One of the most surprising discoveries he made Gaia unintentionally and without it being the focus of its main mission was the detection of stellar earthquakes or ‘Starquakes’, which consists of small movements recorded on the surface of a star that change their shape and could provide new insights into the inner workings of these distant suns.

Marcelo Miller Bertolami, astronomer from La Plata and independent researcher from Conicet explained to Infobae the work that Gaia has been doing since it was launched nearly 10 years ago. “Gaia is an ESA space telescope whose objective is to determine the distance of the stars with great precision. Observe the sky, seeing the position of the stars precisely. The Earth is changing its position in space. And so do the stars. Gaia is a medium rare telescope. It is not a conventional telescope, like Hubble is. Its main advantage is how polished its silicon carbide mirrors are for observing stars and objects at great distances. They are polished at a very high pressure: 10 nanometers, which is 10 millionths of a millimeter. Almost the separation of atomsMiller Bertolami explained.

The latest data release from the European Gaia mission reveals our galaxy, the Milky Way, in new colors.  (Image credit: ESA/Gaia/DPAC)
The latest data release from the European Gaia mission reveals our galaxy, the Milky Way, in new colors. (Image credit: ESA/Gaia/DPAC)

“His work allows several parallel studies, fundamentally on the stars and the origin of the Milky Way. By knowing the distance, one can know the intrinsic brightness of the stars. This will also allow us to improve the age of the stars and the very history of our galaxy. Gaia measures each star many times. In addition to measuring positions, it measures brightness. Measure several million stars multiple times. Each star, on average, will be measured about 70 times, which allows us to observe how their brightness changes”, added the astronomer.

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The discovery of stellar earthquakes is quite surprising since the spacecraft was not designed to do such a job.”, assured a reference of world astronomy, such as Dr. Conny Aerts, of the Catholic University of Leuven, in Belgium, at a press conference of the European Space Agency (ESA) on Monday, June 13, in which he participated Infobae. “These vibrations cause the stellar gas to move up and down. And the brightness of the star changes as a function of time. Then it makes the stars twinkle in the sky”, the expert completed.

It can thus be determined whether the stars have pulsations. With the precision of Gaia, this determination of the period of oscillation of the stars can be made. They are variations in brightness that occur due to the vibration of the star itself. And that vibration tells us about earthquakes or earthquakes. And depending on how they are made, on their changing core, they vibrate in different ways. When a star vibrates, there are variations in the star’s brightness over time. And that is in charge of studying asteroseismology, a branch of astronomy that is very booming these days.”, assured Miller Bertolami.

The expert clarified that Although the material with which stars are formed is usually similar, such as hydrogen and helium, over time, the universe has “got dirty”, due to heavier chemical elements that can originate with material from planets, comets, asteroids, and other dying stars. “Each star changes its internal chemical composition. Today the sun generated more helium than when it was born due to the nuclear generation of the last 5 billion years that it has, “said Miller Bertolami.

Los Starquakes were discovered in a subset of observations focused on the distribution of variable stars in the Milky Way galaxy., that is, stars whose brightness changes over time. “Blinking stars offer astronomers a very powerful tool to study their internal physics and chemistry,” said Aerts. “It is like earthquakes on Earth. Seismologists love earthquakes if they are not too violent, because they allow us to understand what is happening inside our planet. And asteroseismologists do the same thing, but with the stars.”

on the hunt for exoplanets

The two new exoplanets, HD 260655 b and HD 260655 c, are larger than Earth.
The two new exoplanets, HD 260655 b and HD 260655 c, are larger than Earth.

The data published by the ESA generated multiple published scientific studies. One of them It is the one that has the Argentine as a participant Nicolás Unger, graduate in Physics from the UBA and doctorate in astrophysics and exoplanets.

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I study the universe and look for planets outside our solar system. For this, Gaia is a very important mission, since it not only generates the largest catalog of stars, which today has more than 1800 million, but it is also very precise to measure their position, which is what we call astrometry in astronomy. That allows us to know where the stars are in the sky and the distance between them and us”, he explained. Unger to Infobae.

These observations are very useful for finding exoplanets, since if one observes that if a star moves in a circular way in the sky, it means that there is an object that is orbiting it around. Analyzing the type of movement we can deduce if it is a planet or another star that orbits around it. Recently, the third Gaia data release was published, featuring the first catalog of exoplanets. An investigation in which I was able to participate,” said the specialist in worlds not neighboring Earth.

The Gaia space observatory is a spacecraft designed specifically for astrometry
The Gaia space observatory is a spacecraft designed specifically for astrometry

Of all the stars that Gaia observes, some are extracted that we think may host exoplanets. Those stars are calculated what the orbit of that exoplanet would be. So, we extract its orbit and pass it through a validation filter since the measurement made today by Gaia is the first of its kind and needs permanent checks. My job is that. Review and validate Gaia data. We do this by looking to see if that exoplanet had already been discovered by some other method. For that we use the radial speed that consists of measuring the speed of the star. If one sees the oscillatory movement in the star through time, we can deduce that there is an exoplanet. This is a very studied technique, with which the first exoplanet was discovered, for example” specified Unger, who has been working with Gaia today in Geneva, together with collaborators from Italy and Spain.

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In August 2015, Gaia completed its first year of science observations, during which he recorded 272 billion positional or astrometric measurements, 54.4 billion photometric data points, and 5.4 billion spectra. On September 14, 2016, ESA released its first Gaia dataset. which included positions and G-magnitudes of approximately one billion stars based on observations from July 25, 2014 to September 16, 2015.

All-sky map of the Milky Way in motion using Gaia data.  (LAPORTE ET AL)
All-sky map of the Milky Way in motion using Gaia data. (LAPORTE ET AL)

On April 25, 2018, ESA published a second data set that included the positions of approximately 1.7 billion stars, as well as a measure of its overall brightness in optical wavelengths. Now, with this third report, astronomers are partying and promise to reveal more surprises captured by Gaia. Gaia’s June 13 data release also contains the largest dataset ever compiled of binary star systems in our galaxy., that is, pairs of stars (or stars and black holes) that orbit each other. “This is something that the astronomical community is very excited about because binary stars, for example, are the only way you can measure the mass of stars directly,” said Anthony Brown, an astronomer at Leiden University, the Netherlands.

The name Gaia originally derived as an acronym for Global astrometric interferometer for astrophysics. This reflected the optical interferometry technique that was originally planned for use on the spacecraft. Although the working method evolved during the studies and the acronym is no longer applicable, the name Gaia was kept to give continuity to the project. The total cost of the mission is around 1 billion dollars, including manufacturing, launch and ground operations, for a mission that will take 15 years to complete. Although since its detectors are not degrading as fast as initially expected, the mission could be extended.

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