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Dead Planet Orbiting Dead Star Offers Glimpse Of What Could Happen To Earth

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A fragment of a planet that survived the explosion of its host star has been discovered in shockingly close orbit of its dead host.

This strange tableau offers a glimpse of what Earth and the solar system could look like once the sun expires.

Planet Fragment Orbits Dead Star

In a new study published in the journal Science, astronomers report a planetesimal orbiting a dead star 410 light-years away. It was spotted floating in a disk of debris around a white dwarf, which is the remnant ultra-dense core of a dead, burnt-out star.

This debris disk was the original subject of the team's observations using the Gran Telescopio Canarias. During their observations, the researchers found a stream of gas emanating from a solid object within the disk.

The object is estimated to be from just over half a mile (1 kilometer) to a few hundred miles in size. It completes a full orbit every two hours, which means it is extremely close to the burnt-out core.

Mysterious Earth-Like Fragment

Evidence suggests that this mysterious object is a piece of a now-dead planet that used to be part of the star's system. Now, it survives in incredibly tight orbit around the stellar corpse.

In a press release from the university, lead author Christopher Manser of the University of Warwick's Department of Physics reveals that the original star would have been twice the mass of the sun. Now, the white dwarf is only about 70 percent of the sun's mass.

This compact size means that the white dwarf is extremely dense, which makes the planetary fragment's tight orbit all the more amazing to the scientists.

"The white dwarf's gravity is so strong — about 100,000 times that of the Earth's — that a typical asteroid will be ripped apart by gravitational forces if it passes too close to the white dwarf," Manser explains.

His co-author Boris Gaensicke agrees, pointing out that the planetesimal was discovered so deep in the white dwarf's gravitational field, a space where the scientists were not expecting to find anything alive.

There are only two reasons for its survival: either it's extremely dense and/or it has considerable internal strength holding the object together. As such, the team surmises that the planetesimal is likely composed of iron and nickel.

A Potential Future Of The Solar System

The study authors say that their unique discovery potentially foretells the future of the solar system.

Stars age and develop into red giants, Manser explains, which involves the sun eventually destroying Mercury, Venus, and Earth. All the planets beyond Earth will likely survive and simply move further.

"The general consensus is that 5-6 billion years from now, our Solar System will be a white dwarf in place of the Sun, orbited by Mars, Jupiter, Saturn, the outer planets, as well as asteroids and comets," Manser adds. "Gravitational interactions are likely to happen in such remnants of planetary systems, meaning the bigger planets can easily nudge the smaller bodies onto an orbit that takes them close to the white dwarf, where they get shredded by its enormous gravity."

Aside from predicting the future of the solar system, the study findings also highlight the value of using spectroscopy in discovering planets and planetesimals further out in the universe.

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