Planet orbiting dead star gives glimpse into the aftermath of the Sun’s demise

  • Artist’s rendition of a newly-discovered Jupiter-like exoplanet orbiting a white dwarf, or dead star. This system is evidence that planets can survive their host star’s explosive red giant phase and is the very first confirmed planetary system that serves as an analog to the fate of the Sun and Jupiter in our own solar system. Image by W. M. Keck Observatory/Adam Makarenko

A Maunakea telescope has discovered a distant solar system that could indicate what our own solar system will look like after the Sun dies.

Researchers using the W. M. Keck Observatory on Maunakea detected a white dwarf star near the center of a galaxy orbited by a planet much like Jupiter.

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White dwarf stars are the eventual fate of “main sequence” stars, which include the Sun. As the star burns off the last of the hydrogen in its core, it expands into a red giant star before eventually collapsing into a white dwarf star about the size of the Earth.

When the Sun dies, it will expand to thousands of times its size, encompassing the orbits of Mercury, Venus and, most likely, Earth, destroying the planet. But because the newly discovered white dwarf still has at least one orbiting planet, that process could leave outer planets like Jupiter intact.

“This evidence confirms that planets orbiting at a large enough distance can continue to exist after their star’s death,” Joshua Blackman, the study’s lead author and astronomy postdoctoral researcher at the University of Tasmania in Australia, said in a statement. “Given that this system is an analog to our own solar system, it suggests that Jupiter and Saturn might survive the Sun’s red giant phase, when it runs out of nuclear fuel and self-destructs.”

The planet orbiting the white dwarf is estimated to be about 40% more massive than Jupiter, which is itself more than 300 times more massive than the Earth.

The Sun is expected to begin its transformation into a red giant in approximately 5 billion years, at which point Earth will become uninhabitable. However, the new study suggests that in the future, what remains of humanity could find refuge among the moons of Jupiter or Saturn.

“If humankind wanted to move to a moon of Jupiter or Saturn before the Sun fried the Earth during its red supergiant phase, we’d still remain in orbit around the Sun, although we would not be able to rely on heat from the Sun as a white dwarf for very long,” said David Bennett, co-author of the study and senior research scientist at the University of Maryland.

That said, it is still unclear whether all Jupiter-like planets will outlive their host stars.

NASA’s upcoming Nancy Grace Roman Telescope mission — an orbiting space telescope expected to launch in 2027 — is intended to directly image distant giant planets, which will help determine whether it is common for such planets to survive, or if they tend to be destroyed as their star dies.

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“This is an extremely exciting result,” said John O’Meara, chief scientist at Keck Observatory, in a statement. “It’s wonderful to see today an example of the kind of science Keck will be doing en masse when Roman begins its mission.”

Email Michael Brestovansky at mbrestovansky@hawaiitribune-herald.com.

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