NASA Found an Exoplanet Orbiting Around a Dead Star

White dwarfs are the remnants of stars just like our Sun who exhaust their fuel and collapse into very dense cores, usually the size of Earth or even smaller. Finding a large planet somehow orbiting one of these stellar corpses is beyond rare and raises new questions about when a planetary system truly “dies”.

The exoplanet itself is roughly the size of Jupiter, and laps its host star in just 34 hours; over 60 times faster than Mercury laps the Sun. What’s most bizarre about this system is that because white dwarfs are so small, the planet is actually much bigger than the star itself. Because of this, the planet can block all of the starlight from reaching Earth, making it easier to detect than smaller planets.

The discovery has caused confusion because the formation of a white dwarf is almost always violent and chaotic for any orbiting planet. When Sun-like stars age and begin dying, they first expand into red giants, which often engulf the entire inner system before eventually collapsing back down and forming a white dwarf. Because of this, astronomers thought it would be impossible for any planets to survive such an event, and yet WD 1856 b seems to have done just that.

Researchers think that the planet likely formed much farther away from the star than it is now, and eventually migrated inwards after the star’s violent death. This kind of migration is actually more common than many people realize - Jupiter and Saturn have migrated closer to the Sun in the distant past. Migrations can be caused by gravitational interactions with other planets, or even with nearby star systems.

Discoveries like this are crucial because white dwarfs give us a unique opportunity to study the evolution of planets, which can help us learn the fate of our own. Future observations could tell us if smaller worlds like Earth also survive the deaths of Sun-like stars.