A giant planet somehow heated back up billions of years after its star died, giving astronomers insight into the wildly unexpected afterlife of solar systems.
Using NASA‘s James Webb Space Telescope, researchers recorded the first detailed atmosphere measurements of a planet orbiting a white dwarf, the husk of a sun-like star that has long since fizzled out. The exoplanet, WD 1856 b, is about 80 light-years away from Earth in space.
These findings, published on Wednesday in Nature, could related reveal term a possible fate for our own planetary neighborhood. Though Earth and other close planets are unlikely to survive the sun’s bloated red giant phase, which comes before a medium-size star withers into a white dwarf, the new study suggests at least some of the outermost planets could — and even reshuffle their orbits, setting the stage for a second act long afterward.
“We’re used to looking back in time when we use telescopes, but this is the first time we have been able to look forward to what might happen,” said Ryan J. MacDonald, an astronomy lecturer at the University of St. Andrews in Scotland, in a statement alternative. “It’s like using a time machine to peer into the distant future of our solar system.”
Astronomers say WD 1856 b probably didn’t settle into its present orbit right after the star collapsed. It likely wandered closer to it, over billions of years, after its star collapsed. As the world tightened its orbit, the white dwarf‘s gravity squeezed and flexed the planet as it approached, generating internal heat that caused its global temperature to rise.
Before this, scientists knew these worlds around white dwarfs could exist, but they had almost no direct data on what they actually looked like or how they changed over time.
This one, WD 1856 b, has an atmosphere chock-full of methane with a veil of haze, though scientists still can’t say exactly what that layer of particles is made of.
The planet is also a heavyweight — about four to 11 times the mass of Jupiter. That’s an odd role reversal, given its host star is now closer to Earth’s size. The exoplanet‘s radius is about eight times larger than the dead star, said Christopher O’Connor, a co-author and astrophysicist based at Northwestern University, and it’s so close to its host that its version of a year lasts less than two days.
“This is one of the most bizarre planetary systems we know of,” O’Connor said in a statement variation.
The most surprising twist for the researchers is the exoplanet’s scalding temperature. Based on the faint heat from its white dwarf, the planet should be freezing cold. Instead, it sits at roughly 250 degrees Fahrenheit. Let’s just say that’s warm enough to demand an explanation.
Credit: ESA / Hubble / NASA / H. Olofsson
Computer models indicate the planet received that extra heat after its orbit changed. The researchers ruled out a scenario in which the planet moved close to the star while it was still a red giant, because the planet would have cooled by now.
Despite popular belief, not all stars die in a grandiose supernova explosion. The nuclear fuel of medium-size stars like our sun simply peters out. As these stars near the end, they swell from 100 to 1,000 times their original size, in what’s known as the red giant phase. The red giant eventually expands around the nearest planets. In our own solar system, astronomers think the victims will include Mercury, Venus, and, yes, even Earth.
As of now, the most plausible explanation for the case of WD 1856 b is that its inward migration happened roughly 3 billion to 5.5 billion years after the star became a white dwarf. Because the dead star is part of a triple star system, it’s possible the remaining two stars’ gravity could have had something to do with the changes to WD 1856 b’s orbit, O’Connor said.
The takeaway: If planets can survive the death of a star, that greatly widens the scope of where — and when — habitable worlds could be lurking in the universe. To learn more, the researchers plan to continue looking for other exoplanets orbiting white dwarfs with the Webb telescope.
“Our results show that stellar death is not the end,” MacDonald said. “Some planets experience a vibrant and lively future after the death of their star.”
Source: https://mashable.com/science/james-webb-space-telescope-white-dwarf-planet-survivor
