The colossal cosmic cloud known as the Eye of God Nebula, or the Helix Nebula, may have destroyed a Jupiter-like planet that wandered too close to it, according to a new study.
Astronomers may have solved a long-held mystery surrounding the nebula and a strange signal of X-rays coming from within.
What is the Eye of God Nebula?
The Eye of God Nebula – or the Helix Nebula – is a huge cloud of material formed by a dying star.
It's a type of object known as a planetary nebula, which get their name from the fact that most of them appear spherical (not because they have anything to do with planets).
A planetary nebula is the late stage of a star that has used up most of its fuel and begun ejecting its outer layers into space, resulting in a round, puffed-out shape.
What's left behind is a dying stellar ember known as a white dwarf.
X-ray mystery
Astronomers have long known about a strange source of X-rays coming from the dying star.
As far back as 1980, X-ray observatories detected a strange signal coming from the core of the Helix Nebula.
The Einstein X-ray Observatory and ROSAT telescopes found that highly energetic X-rays were coming from the white dwarf.
This dying star, named WD 2226-210, is just 650 lightyears from Earth, making it our closest planetary nebula.
The problem is, white dwarfs don't normally give off strong X-rays.
Armed with newer X-ray space observatories like NASA’s Chandra X-ray Observatory and the European Space Agency's XMM-Newton, astronomers believe they've solved the mystery.
Eye of God Nebula, the planet killer?
Data from Chandra and XMM-Newton may have revealed the source of the X-rays coming from WD 2226-210.
"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," says Sandino Estrada-Dorado of the National Autonomous University of Mexico, lead author of the study.
"We might have finally found the cause of a mystery that’s lasted over 40 years."
Astronomers already knew there was a Neptune-sized planet in a close orbit around the white dwarf.
It orbits the dying star in less than three days.
And this latest study reveals there may have been a planet like Jupiter even closer to the star.
This large gas giant may have originally orbited far from WD 2226-210, but migrated inwards due to gravitational interactions with other planets in the system.
It may have wandered too far and been torn apart by the gravity of the white dwarf.
"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," says 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."
The study shows the X-ray signal has remained largely the same in terms of its brightness between 1992, 1999 and 2002.
But the data suggests there may be a subtle, regular change in the signal every 2.9 hours.
This could indicate that the remains of the planet are still there, orbiting close to the white dwarf.
Could this destroyed body even have been another star, rather than a planet?
The astronomers say that such stars would be about the same size as a Jupiter-like planet, but more massive, making it likely to have been torn apart by the white dwarf.
Increasing the search
The team behind the study of WD 2226-210 say it's similar in terms of x-ray emissions to two other known white dwarfs that are not within planetary nebulae.
One may be sucking material from a planet in orbit, but without destroying it entirely.
The other is probably dragging material from the remnants of a planet onto its surface.
These three white dwarfs could indicate a newly-discovered class of object.
"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," says co-author Jesús Toala of the National Autonomous University of Mexico.
A paper describing these results appears in The Monthly Notices of the Royal Astronomical Society and is available at arxiv.org/abs/2412.07863.
