This nucleus of dead exoplanet could be a preview of the future of the Earth



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The Earth is enjoying the best eons of the sun's life, but that friendly yellow balloon in the sky will not last forever. No matter what we do, the sun will one day destroy the world, leaving a fractured planetary body orbiting a dead star. Astronomers have discovered a distant star system that could offer a preview of Earth's future. It is a white dwarf star with a destroyed planetary core spinning around it.

Stars like our sun have a lifespan measured in billions of years. With 4.6 billion years, the sun is a middle-aged star. It has not changed dramatically in approximately 4 billion years and will remain in its current state for another 4 to 5 billion years. However, energy production will increase over time and in a billion years could make the Earth inhospitable to humans. The real show begins in about five billion years when the sun drains its hydrogen fuel and expands into a red giant. This will destroy the Earth, but maybe not the way we expected.

This happened to the star known as SDSS J122859.93 + 104032.9 in the distant past. This system is 410 light years away. This object is a white dwarf, an ultra-dense stellar nucleus of "degenerated matter by electrons" that remains after the outer layers of the star are thrown into space. Without a normal electron orbital around atoms, gravity can compress the material into a white dwarf like J122859 until it is the size of Earth with 70 percent of the solar mbad.

The Earth, as seen to propitiate its eventual destruction.

Astronomers studied this stellar system using the Gran Canarias Telescope (GTC) of 34.1 feet (10.4 meters) in the Canary Islands. The team determined that the planetary core has a width of approximately 370 miles (600 km) with a density of at least 7.7 grams per cubic centimeter. A little lower and would have been torn by the gravity of the star, as it orbits very close, only 123 minutes per revolution. Its properties are similar to the iron core of the Earth, so the team believes that it is the shell of an ancient destroyed planet. It suggests that dying stars might not completely annihilate their planets, but break them into pieces, leaving only the dense nuclei.

The team used a spectroscopic technique to detect the planetary core around J122859, which is not as accurate as the transit method employed by Kepler. However, it works on more objects. There are six other known white dwarf systems that could have detectable planetary cores.

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