June 24, 2021

Found the corpse of a planet like Earth | Science

Found the corpse of a planet like Earth | Science

Representation of the white dwarf, in the center, and the planetary fragment that orbits it. GETTY

Solar system, within 5,000 million years. The sun has died. Before dying, he swallowed Mercury, Venus and Earth. Mars It is the last rocky planet that still exists. It is an enigma if part of the devastated planets survived and continue orbiting the corpse of its star.

An international team of astronomers has found another star that allows us to travel to the future of our solar system and answer that question. It is 400 light years away and it is a white dwarf, a sun-like star that exhausted its hydrogen fuel billions of years ago. Using the Gran Telescopio de Canarias, one of the largest optical observatories in the world, astronomers have managed to study the composition of the gas cloud that surrounds the star.

"The main reason why we study these stars is that the Sun will end up being one of them," explains Paula Izquierdo, a researcher at the Institute of Astrophysics of the Canary Islands and co-author of the study published today in Science. "When the planets closest to the Sun are engulfed, the tidal forces[[Secondary effect of gravity]they will end up dismembering them. Once the sun shrinks again and becomes a white dwarf, it will be surrounded by a cloud of debris very similar to what we see now, "he says.

In the work released Thursday, astronomers describe the spectral lines that emit the gases found around the star, called SDSS J122859.93 + 104032.9, and confirm that there is a solid body from which metals are evaporating that can have up to 600 kilometers in diameter. The rock, which would be the equivalent to the skeleton of a corpse planet, orbits so close to its star that it turns around approximately every two hours. Its temperature is about 1,700 degrees and gases suggest that it is made mainly of iron, like the Earth's core.

The astrophysicist Paula Izquierdo with the Great Telescope and the Canaries in the background on the left.
The astrophysicist Paula Izquierdo with the Great Telescope and the Canaries in the background on the left.

The rocky fragment "must be very dense" -explains Boris Gaensicke, researcher at the University of Warwick (United Kingdom) and co-author of the study- "that is why we propose that it be made of iron and nickel". "If it were pure iron it could survive in the orbit in which it is without disintegrating. It is also possible that it contains iron and other consistent materials, which would mean that it could be a large fragment of the nucleus of a planet whose original diameter was at least hundreds of kilometers, since that is the limit from which these bodies begin to generate heavy elements, "he details.

Last year, this same team was the first to discoverthese planetariums around a white dwarf. They were rock fragments in full decomposition. In that case, the alignment was adequate and its transit could be observed in front of the star. The new method used in this study, based on the light emitted by gases, opens the door to discover many more dead solar systems without needing them to be correctly aligned with the Earth.

"One of our next goals is to find and analyze all the white dwarfs some 130 light-years away from the Earth. We will choose those that present metals for a more detailed analysis. Thanks to new instruments that will be installed in several ground-based telescopes, including William Herschel de La Palma [Canarias], we can better study these stars and their planetary remains, which in turn will help us to better understand the end of our own solar system, "concludes Izquierdo.

Luca Fossati, from the Institute of Space Studies, in Vienna, explains in a comment to the study another derivative of this finding. "Because these planetary fragments can be remnants of the core of rocky planets, studying the light spectrum of white dwarfs like this can help us determine the chemical composition and abundance of metals in the planetary nuclei," he says. This includes our own planet, since it is impossible to reach its core to find out exactly what it is made of.


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