A grisly discovery indicates that it is one of the oldest planetary systems in our galaxy

In the atmosphere of an ancient dead star, astronomers have discovered the remains of Earth-like planets that perished long before our planet was born.

Astronomers have found the remains of a real massacre in space. It is a small white dwarf surrounded by planetary debris. Researchers suspect that the star and its planetary debris are over ten billion years old. This makes it one of the oldest planetary systems discovered in the Milky Way so far.

white dwarf star
As a star ages, hydrogen fusion in the star’s core stops and it swells. Then a red giant is created. When the star then blows off its outer layers of gas and dust, the core contracts, leaving a white dwarf. The star has reached the end of her life. Most stars in the universe, including our sun, will one day turn into a white dwarf. This is, as you can imagine, a hostile process, which greatly affects planets orbiting such a star. Most planets will be pulled towards the star and swallowed.

Study
In the new study, the researchers took a closer look at two unusual white dwarfs. “Because 97% of stars will eventually turn into white dwarfs – and so this type of star is ubiquitous in the universe – it’s very important to know more about them,” said Abbigail Elms. One strange white dwarf studied by the researchers turns out to be strikingly blue, while the other is the palest and reddest ever found in our cosmic backyard. Both stars appear to be polluted with planetary debris. Thanks to spectroscopic and photometric data collected by powerful telescopes, the researchers succeeded in determining the age of the white dwarfs. The “red” star, located 90 light years away, turns out to be no less than 10.7 billion years old. About 10.2 billion years ago, it transformed into a white dwarf. The “blue” star is only slightly younger.

Red Star
Further analysis indicates that the red star houses the alkali metals sodium, lithium, and potassium, among others. This makes the ancient star the oldest metal-contaminated white dwarf ever discovered. Additionally, researchers suspect that the planets that once orbited this star managed to sustain themselves for a very long time. The planets may have been destroyed late in the star’s transformation process. The researchers conclude that it is one of the oldest planetary systems ever discovered in our Milky Way.

blue Star
The blue star was also accompanied by planets. This star, after analysis, turns out to be contaminated by planetary debris which has a composition similar to the Earth’s continental crust. The team concludes that the star’s blue color may be due to its unusual atmosphere, which consists of a mixture of helium and hydrogen.

Not unique
The discovery of these metal-contaminated stars shows that Earth is not unique: there are other planetary systems with planetary celestial bodies similar to Earth. “In this study, we found ancient stellar remnants in the Milky Way that contain the remains of Earth-like planets,” Elms says. “It’s amazing to think that this happened around ten billion years ago. These planets then collapsed long before our Earth saw the light of day.

Mystery
Astronomers can determine the abundance of certain metals in the original planetary body by analyzing a star’s spectrum. By then comparing these quantities to planets in our own solar system, scientists can paint a picture of what those planets looked like – before the star died and turned into a white dwarf. But in the case of the red star, this proves to be particularly difficult. “The red star is a mystery,” says Elms. “The accumulated planetary debris is rich in lithium and potassium and unlike anything we know of in our own solar system. This makes it a very interesting and at the same time rare white dwarf, partly due to its ultra-cool surface temperature, its age and the fact that it is magnetic.

While the stars offer new insight into white dwarfs, they also raise new questions. “When these ancient stars formed more than 10 billion years ago, the universe was much less rich in metals than it is today,” said researcher Pier-Emmanuel Tremblay. “That’s because metals form in evolved stars and from massive stellar explosions. Thus, the two white dwarfs studied provide an exciting window to study planet formation in a metal-poor, gas-rich environment – ​​an environment very different from the conditions that prevailed when our own solar system was forming.