Planets Orbiting Dead Stars Foretell the Solar System’s Far-Future Fate

In the distant future—about six billion or seven billion years hence—the sun will start to die, swelling up into a bloated red giant. In a span of several hundred million years it will blow away its outer layers, lose about half its mass and leave behind its überhot, überdense, super small core: a white dwarf.

The inner planets will be toast when this happens. Mercury, Venus and most likely even our precious Earth will be literally consumed by the sun and vaporized as their once benevolent host star literally overruns and engulfs them. But what of the outer planets, such as Jupiter and Saturn? They should survive the ordeal, being so far removed from the solar system’s center. Until now, though, there was scant direct observational evidence that such outer worlds can endure the death throes of their sunlike stellar host.

Using the James Webb Space Telescope (JWST), a team of astronomers led by Susan Mullally at the Space Telescope Science Institute targeted four white dwarfs, hoping to get direct images of any large planets that might still orbit them. Two came up empty, but the other two show evidence of extant giant exoplanets still orbiting them. To be clear, these planets have not yet been confirmed, but if the research pans out, they will act as a glimpse into the future of our sun and its worlds—and that future is not exactly a comforting one. The group’s research, which was posted to the preprint server arXiv.org last month, has been accepted for publication in the Astrophysical Journal Letters.

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The four white dwarfs were chosen for JWST’s scrutiny because there seemed to be good chances that they had possessed planets in their pre-red-giant phases—and that any planets still lingering around them should be straightforward to see. They’re relatively near to the sun in the galaxy, making planets around them easier to spot; from too far away the planets and host stars would blend into a single blob. Also, these white dwarfs are young enough that any extant planets should still be glowing in the infrared from the leftover heat of their formation—that is, the younger they are, the warmer they are and the easier JWST can spot them.

Most importantly, though, previous…