Exoplanetary cemeteries: strange space rocks were discovered – Science – life

Astronomers have recently discovered unprecedented types of rocks, made up of an unusual proportion of minerals, and found them in the remnants of cosmic worlds that shattered the dying stars of the domains. Research indicates that these exoplanets are built from a much wider range of materials than previously thought.

Source: Sputnik

Photo: Profimedia

Photo: Profimedia

In a new study, researchers studied 23 white dwarfs, small and dense remnants of dead stars of low and medium mass, 650 light-years from the Sun. When these stars died and became white dwarfs, they scattered their exoplanets into orbit.

The atmosphere of these white dwarfs contains the interior of the worlds they have destroyed. The researchers worked on the relationship of different elements in the atmosphere of white dwarfs by analyzing the light emitted by stars, and then calculated the most likely mineral composition.

Researchers have found that only one of the white dwarfs contains the remains of an exoplanet with a geological composition similar to that of Earth. In other dead stars, they found remnants of exoplanets made of rocks that have never been seen on our planet or in the rest of the solar system.

“While some exoplanets that once orbited white dwarfs look like Earth, most have exotic rock types for the solar system. They have no direct counterparts to the solar system,” said lead author Xi Xu, a National Laboratory astronomer. of Optics. Infrared astronomy in Arizona. in a statement.

Exoplanetary cemeteries

White dwarfs are astronomical objects that form when major stars, such as the Sun, run out of fuel to burn and offer to turn into red dunes before submerging by their own weight in supercondensed stellar nuclei. refrigerated. During this process, these dying stars release a cloud of overheated gas that swallows the planets around them.

Some exoplanets can withstand this cosmic game, but most are ejected from their orbit and then scattered by the white dwarf’s strong gravitational field. This is known as tidal perturbation: when a planet splits, a white dwarf drags planetary debris within a process known as accretion.

Normally, the atmosphere of the white dwarf contains only hydrogen and helium, because all these elements sink into the superdense core of the star. Thus, when light emitted by stars indicates the presence of other heavier elements, researchers assume that it must have come from the accretion of exoplanets.

Scientists have estimated that about 25 percent of all white dwarfs contain the remains of dead exoplanets or are so-called contaminated white dwarfs. These exoplanet cemeteries have become a serious topic among astronomers because scientists can use them to establish the properties of the bodies that once contained them.

Reconstruction of rock types

In the new study, researchers focused on contaminated white dwarfs that already had accurate measurement data showing the proportion of magnesium, calcium, silicon and iron in their atmosphere. Astronomers believe that these elements are common in the core and shell of exoplanets, which make up most of the planets beneath the outer crust. By calculating the proportion of these elements, scientists can identify the minerals that would form the rocky bowels of the planets.

To do so, they used calculations that previously “worked very well” to “classify the rocks on Earth” with similar data, said co-author Kate Putirka, a geologist at California State University, reports “Live Science.”

However, the results revealed that the “surprising” majority of the minerals that made up these exoplanets were very different from what they expected, Putirka said.
“On Earth, the rocks of the shell mainly consist of three minerals, olivine, orthopyroxene, and clinopyroxene,” Putirka said. But the proportion of elements in most contaminated white dwarfs has shown that none of these minerals are likely to form, “Sputnik added.

Instead, other minerals would be formed from different formulations of periclase and quartz rich in magnesium, which is a crystalline mineral made of silicon dioxide, different from those predicted on other inner planets in the solar system, Putirka said. This contradicts the above assumptions that exoplanets would be more similar to those we see in the solar system.

These minerals are so different from what we know that researchers had to create new names to classify them, such as “quartz pyroxenites” and “periclase dunites.” However, it is unclear how many new minerals exist in these white dwarfs. “New experiments are needed to fully understand the mineralogy of the new compositions,” Putirka said.

Interior versus exterior

In the past, studies of the atmosphere of polluted white dwarfs had focused on whether exoplanets have a continental crust like that of Earth.

Scientists believe that the continental crust is vital to sustaining life on the planet because it provides a stable structure for evolution.

Therefore, the probability that exoplanets have crusts could answer questions about the possibility of extraterrestrial life or the ansam to find an Earth-like exoplanet.

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