Exoplanet may have gotten ‘facelift’ through stellar regeneration

Chuck Bednar for redOrbit.com – @BednarChuck

A team of astronomers have found tentative evidence that an extrasolar gas giant may have received the intergalactic equivalent of a facelift due to a hypothetical phenomenon called stellar rejuvenation, during which material from a dying sun caused it to swell and warm up.

According to Discovery News, stellar rejuvenation has thus far been “pure conjecture,” but now NASA researchers have reportedly found a distant planet in orbit around a white dwarf called PG 0010+280 that might have regained its youthful infrared glow as a result of this phenomenon.

The candidate planet was detected using the Spitzer Space Telescope, and its appearance is that of a planet several billion years younger than its actual age, they explained in a statement. When planets are young, they still glow with infrared light, but as they grow older and cooler, that glow disappears. Rejuvenated planets, however, would be visible again.

Possible evidence that planets can survive the red giant stage

When a star runs out of fuel, it becomes a red giant, and strong stellar winds will eject the star’s plasma layers into space, Discovery News explains. Ultimately, it will create a planetary nebula with a small, dense white dwarf in the core. So what happens to the plasma that was shot out into space? One theory says that it may fall back down onto far off gaseous exoplanets.

These planters would have been cooling off over the billions of years since they first formed, but if they accumulated stellar plasma from a dying star, they would once again become much hotter, increase in mass, and appear to be younger than they truly are. While this remains just conjecture at this point, new research may have uncovered the first actual proof of this phenomenon.

Researchers from UCLA first found unexpected infrared light around PG 0010+280 as they were looking at data from the NASA Wide-field Infrared Survey Explorer (WISE) – a discovery that was confirmed in follow-up observations made with Spitzer in 2006. At first, they believed that the extra infrared light was coming from a disk of material around the white dwarf, but recently, roughly 40 addition disks have been spotted around these dead stars.

In most cases, these disks are believed to have formed by asteroids that traveled to close to the white dwarfs and wound up being shredded, but the Spitzer data for PG 0010+280 didn’t seem to fit with this model. It could be that the infrared light is originating from a nearby companion “failed” star (a brown dwarf), or it could be coming from 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,” explained UCLA’s Siyi Xu. “If confirmed, it would directly tell us that some planets can survive the red giant stage of stars and be present around white dwarfs.”


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