Scientists: Dwarf stars feed on remnants of the ancient Earth-like world

by time news

The main-sequence life of a star like the Sun might not end in a supernova like more massive stars, but it wouldn’t be an ordinary issue; When a star runs out of fuel and becomes unstable, it grows to an extremely massive size before exploding from its outer matter while the core collapses into a tiny, extremely dense white dwarf.

For the Sun, that red giant phase could extend to Mars; A process that can destabilize and destroy planets.

We’ve seen white dwarf stars with planets, indicating that they can survive the process (or form after it). But, increasingly, scientists have discovered that many exoplanets are devoured by this white dwarf, according to the specialized scientific website “Science Alert”, citing data from the Royal Astronomical Society Periodic.

According to the association, the “pollution” caused by planetary elements in the atmosphere of white dwarf stars, whose study is known as dead planet science, could be the reason for this. Now, astronomers have discovered the oldest known example of this; It is manifested by an exoplanet devoured by a white dwarf that formed 10.2 billion years ago.

About 90 light-years from Earth, the white dwarf is incredibly small and faint, and its color is more unusual than any other white dwarf star. A second, unusually blue white dwarf star formed 9 billion years ago.

The new study team also found that both stars face constant pollution by inundating planetary debris.

However, while the red star (named WD J2147-4035) is the oldest polluted white dwarf discovered to date, the blue star (named WD J1922 + 0233) is probably more interesting, as elements in its atmosphere indicate that it is It eats a planet very similar to Earth.

“We found the oldest stellar remnants in the Milky Way contaminated with Earth-like planets,” says astrophysicist Abigail Elms at the University of Warwick, UK. Earth,” explaining, “We can dissect the chemical composition of the star’s atmosphere from the light produced by the star. where not all wavelengths are emitted equally; Some are stronger and some are weaker. This is because the elements can absorb and re-emit light, changing the spectrum of the light coming out of the star. It’s not immediately clear which elements play a role, but scientists are gaining experience in identifying the absorption and emission features on the spectrum associated with the elements.”

When the European Space Agency’s Gaia space observatory identified the unusually colored white dwarfs, Elms and his colleagues subjected the two strange spheres to various studies.

Because white dwarf stars no longer function by fusing elements in their cores, their temperatures are slowly declining at a known rate; And that by measuring the temperatures of the two stars, the researchers were able to measure the time since their formation from the death of a sun-like star. Next, the scientists subjected the spectra of the stars to analyzes in order to determine the compositions of their atmospheres; They found sodium, lithium, potassium and possibly carbon on the red star, while they found sodium, calcium and potassium on the blue star.

Because white dwarfs are so gravitational, heavy elements like this should disappear into the white dwarf’s interior undetected very quickly; This indicates that the material that produces these elements is still falling on the stars from the clouds of debris around them.

In the case of WD J2147-4035, the team determined that the pollution may have been the remnants of a planetary system that orbited the star before its death and survived the throes of stellar death, and is now slowly falling over billions of years; Since the star turned into a white dwarf more than 10 billion years ago, this makes it the oldest known planetary system in the Milky Way (although it has broken up and disappeared).

Meanwhile, the contaminated debris of WD J1922 + 0233 has a composition similar to Earth’s continental crust, indicating an Earth-like planet orbiting a sun-like star that lived and died billions of years before the formation of the solar system; It’s like the galactic fossil record that can tell us what the Milky Way’s planetary systems were like eons before this intrigued us.

For his part, says astrophysicist Pierre Emmanuel Tremblay at the University of Warwick, “When these ancient stars formed more than 10 billion years ago, the universe was less rich in minerals than it is now; Where minerals form in advanced stars and giant stellar explosions. The observed white dwarfs provide an exciting window for planet formation in a mineral-poor, gas-rich environment that was different from conditions when the solar system was formed.


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