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When our sun goes into death throes in about five billion years, it will burn our planet and then dramatically turn into a dead ember known as a white dwarf. But the fate of more distant planets like Jupiter or Saturn is less clear.
Wednesday in the journal Nature, astronomers reported that they’ve observed an exciting preview of our solar system’s afterlife: a Jupiter-sized planet orbiting a white dwarf about 6,500 light-years from here.
Known as MOA-2010-BLG-477Lb, the planet has an orbit comparable to Jupiter. The discovery not only offers a glimpse into our cosmic future, it also raises the possibility that any life on “surviving” worlds could withstand the death of their star.
“While there is a fair amount of evidence of rocky planetary debris orbiting white dwarfs, we have very few data points for pristine planets,” said Joshua Blackman, a postdoctoral researcher at the University of Tasmania and lead author of the study.
“The fate of our solar system will likely be similar to MOA-2010-BLG-477Lb,” he added in an email. “The sun will become a white dwarf, the inner planets will be swallowed up, and larger orbiting planets like Jupiter and Saturn will survive.”
The planet was first detected due to the light-distorting effects of the gravitational field, a phenomenon known as microlensing. Dr. After years of searching for its host star with the Keck II telescope in Hawaii, Blackman and colleagues concluded that it orbits a white dwarf too faint to observe directly.
Astronomers using a different method reported last year Detecting another pristine Jupiter-like planet orbiting a white dwarf known as WD 1856 b. But MOA-2010-BLG-477Lb surrounds the hidden stellar shell about three times the distance between Earth and the sun, making it the first planet known to have a Jupiter-like orbit around a white dwarf. By contrast, WD 1856 b orbits its white dwarf every 1.4 days, suggesting that its star migrated to its current position after its death, but the exact mechanics of this journey still being hashed.
Andrew Vanderburg, an assistant professor of physics at the Massachusetts Institute of Technology, who led the team that discovered WD 1856 b, said the results of the new study look solid. He also noted that planets with wide orbits around white dwarfs are likely more abundant than those found in narrow orbits, but the latter group is easier to detect.
Dr. “If I had to guess, I’d say theirs is a much more common population because he just has to stay there and nothing happens to him,” Vanderburg said. “This seems like the most likely outcome to me, at least at this point in the history of the universe.”
New discoveries may offer insight into the search for extraterrestrial life and the potential habitability of white dwarf systems. Lisa Kaltenegger, director of the Carl Sagan Institute at Cornell University, has suggested that some life-bearing star systems may experience what she calls herself. “a second creation” where new organisms emerge in the reconstructed fallout of a white dwarf system.
As part of the team that discovered WD, Dr. “I find the work exciting because it adds to the growing evidence that planets can survive the death of their stars, which raises intriguing questions about the future of the cosmos,” Kaltenegger said. 1856 b, in an e-mail. “If planets can survive the death of their stars, can life survive?”
As dying stars transform into a phase called red giants, they emit harmful radiation and create turbulence in their systems that can destroy life. But there are some speculative scenarios that could preserve the habitability of white dwarf systems.
Dr. “There’s a lot of things that need to go right,” Vanderburg said. He imagines a planet far away from a red giant star, which then moves inward after the star becomes a white dwarf, holding “enough water to potentially be a nice place to live” when the star transforms into a white dwarf.
Because white dwarfs are small and faint, such a planet must be in very close orbit for liquid water to exist. However, if life does emerge on a world like Jupiter’s moon Europa, which may contain a subterranean ocean heated by Jupiter’s tidal forces, it could potentially survive at a greater distance from the star.
Dr. “If humanity is somehow still around five billion years later, we probably would have a better chance of surviving the red giant phase of the sun on Jupiter’s moon than on Earth,” Blackman said.
While the existence of life around white dwarfs remains a matter of speculation, next-generation observatories, such as James Webb Space Telescope and Nancy Grace Roman Space Telescopecan help provide concrete answers to some of these evocative questions. As more robust planets orbit white dwarfs become visible, scientists will get a clearer picture of the life and afterlife of these mysterious systems.
Dr. “This is the first detection using microlensing of a planet orbiting a white dwarf,” Blackman said, “almost certainly not the last.”
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