New gas-giant planet found orbiting white dwarf star

Astronomers have discovered evidence of a gas-giant planet orbiting a white dwarf star in the Milky Way.

Models have suggested planets of this size in a similar orbit might have been able to survive the death of their host stars from the giant phase into white dwarfs.

But no such planet has previously been observed.

The new research indicates the gas-giant, Jupiter-mass planet is orbiting a white dwarf star in a wide orbit in the Milky Way.

White dwarfs are stars that have burned up all of the hydrogen they once used as nuclear fuel.

White Dwarf System (W M Keck Observatory/Adam Makarenko/PA)
White Dwarf System (W M Keck Observatory/Adam Makarenko/PA)

Joshua Blackman, from the University of Tasmania, Australia, and colleagues determined that it formed at the same time as its host star.

According to the study, the planet managed to survive after the star stopped burning hydrogen in its core.

Gas-giant planets orbiting white dwarfs are typically thought to move to orbits five or six astronomical units (AU) away but this planet is around 2.8 AU from its star.

The researchers say their findings provide evidence that planets can survive the giant phase of their host star’s evolution, and support the prediction that more than half of white dwarfs will have similar planetary companions.

The findings are published in Nature.