New evidence supports planet ‘rejuvenation’ theory

Scientists have discovered infrared light surrounding a white dwarf that could support the theory that massive, ageing planets can regain their infrared glow.

Rejuvenated planetMAIN

Artist’s concept showing the hypothetical ‘rejuvenated’ planet with its infrared glow. Image credit: NASA/JPL-Caltech

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Astronomers have found new evidence to support a theory that massive planets could ‘rejuvenate’ and regain the youthful, infrared glow that they lose as they begin to age.

The theory suggests that planets as big as Jupiter could accumulate mass from their dying stars, causing them to heat up as a result of friction created by the falling material, making them swell and glow red again.

“When planets are young, they still glow with infrared light from their formation,” says Michael Jura of the University of California, Los Angeles (UCLA). “But as they get older and cooler, you can’t see them anymore. Rejuvenated planets would be visible again.”

New research using NASA’s Spitzer Space Telescope has led scientists closer to confirming this theory for the first time.

The study looks at a white dwarf, which is a dead star, called PG 0010+280.

Infrared light was discovered around the star by Blake Pantoja at UCLA while he was looking at data from NASA’s Wide-field Infrared Survey Explorer (WISE).

Scientists then looked at Spitzer observations of the same star from 2006, which also showed infrared light.

It was initially supposed that the light could come from a disk of material surrounding the white dwarf, thought to have been formed by the dead star’s gravitational pull chewing up material from a nearby asteroid.

But Spitzer data for PG 0010+280 did not fit with simulated models for asteroid disks, leading the team to infer that the infrared light is either coming from a brown dwarf – a ‘failed’ star – or a rejuvenated planet.

“I find the most exciting part of this research is that this infrared excess could potentially come from a giant planet, though we need more work to prove it,” says Siyi Xu of UCLA and the European Southern Observatory in Germany.

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“If confirmed, it would directly tell us that some planets can survive the red giant stage of stars and be present around white dwarfs.”