The Helix Nebula May Actually Be The Real 'Death Star' - Here's Why

All good things must come to an end, and that is even true for planets. Recent research has uncovered what appears to be the grizzly death of an exoplanet in the nearby Helix Nebula, which seems to have been devoured by a dying star.

Researchers have been detecting X-ray signals coming from the center of the Helix Nebula since the 1980s, but they were never sure of the cause. Now, data from two X-ray telescopes, NASA's Chandra X-ray Observatory and the European Space Agency's XMM-Newton, has uncovered the grim fate of a planet there.

The Helix Nebula is called a planetary nebula (confusingly, this name has nothing to do with planets but is a historical artifact arising from a mistake by scientists in the 19th century), which means it is formed around the core of a dying star. As the star throws off layers of material from its outer edges, this gas and dust form a bubble shape that spreads out from the center.

At the center of the nebula is the culprit of this mystery: the small, dim remaining core of a star called a white dwarf.

It is this white dwarf, named WD 2226-210 and located just 650 light-years from Earth, that is giving off the X-rays. And new data shows that these signals could be the final remnants of what was once a planet in the star's orbit.

Scientists believe that a Jupiter-like planet once orbited the star and that it could have been pulled inward over time before being torn apart by the star's epic gravity.

"We think this X-ray signal could be from planetary debris pulled onto the white dwarf, as the death knell from a planet that was destroyed by the white dwarf in the Helix Nebula," explained lead author of the paper published in "The Monthly Notices of the Royal Astronomical Society," Sandino Estrada-Dorado of the National Autonomous University of Mexico. "We might have finally found the cause of a mystery that's lasted over 40 years."

There is known to be another planet in the same system, a Neptune-sized planet that is orbiting extremely close to the star, with a year there lasting less than three Earth days, so the idea that there could have been another planet there at some point in the past is not unreasonable.

The theory goes that as this Jupiter-sized planet was ripped up, pieces of it were drawn in by the star's gravity, and as they fell onto the white dwarf's surface, they became extremely hot, causing them to give off X-rays.

"The mysterious signal we've been seeing could be caused by the debris from the shattered planet falling onto the white dwarf's surface, and being heated to glow in X-rays," said co-author Martin Guerrero of The Institute of Astrophysics of Andalusia in Spain. "If confirmed, this would be the first case of a planet seen to be destroyed by the central star in a planetary nebula."

This finding isn't only a grizzly curiosity. It is also an important way for scientists to learn about how planets evolve over time and eventually die.

Although this is the first case of its type to be discovered, the researchers believe that there may be more star systems like this one out there. They also considered the possibility that the object that was destroyed and dropped matter onto the white dwarf could have been another star rather than a planet, though stars that are as small as a Jupiter-sized object are denser and more massive, so they are less likely to have been ripped apart by gravitational forces.

"It's important to find more of these systems because they can teach us about the survival or destruction of planets around stars like the Sun as they enter old age," said co-author Jesús Toala of the National Autonomous University of Mexico.

There are two other known white dwarfs that give off similar patterns of X-rays to WD 2226-210, though these are not located in planetary nebulae. These two other white dwarfs are thought to be also experiencing a rain of material onto their surfaces that comes from nearby planets is the throes of destruction, but perhaps at a different speed to this one.

As these three objects give off intermittent X-ray signals, they are known as variable objects, and the researchers believe that they may constitute a new group of objects within this classification.