The fate of our solar system when the sun dies is a topic of great interest and concern. As the sun transitions into a white dwarf about a billion years after the red giant stage ends, the rest of the planets in our solar system will continue to orbit the dead star. But what will happen to our solar system's largest planets, such as Jupiter and Saturn? A recent study offers a preview of what may await our solar system's fate. The study focuses on a giant exoplanet, WD 1856 b, which was detected in 2020 orbiting a dead white dwarf star. The planet is seven times larger than its Earth-size star and completes one orbit around the dead star every 34 hours, at a distance of less than 2 million miles. This close proximity to its host star has baffled astronomers, as they were unsure how the planet survived its host's destruction. The study's findings suggest that huge planets can survive the demise of their host stars in ways previously thought impossible. The planet's tight orbit and the lopsided relative sizes of WD 1856 b and its host star motivated the researchers to investigate further. They used the James Webb Space Telescope to capture the latest glimpses of the planet and measure its atmosphere, mass, and temperature. The results showed that the planet originally orbited the star from a safer, much greater distance. But WD 1856 b heated up while migrating inward after the star died. The researchers have two competing theories about how WD 1856 b ended up in its current, tight orbit. The "engulfment model" suggests that the planet was actually swallowed by the host star as it ballooned in size before dying but managed to survive. The "gravitational interaction model" alternatively proposes that WD 1856 b avoided the star's death throes, but the gravitational influence of other objects in the system pushed it closer to the white dwarf. The team's data seems to indicate that heating of the planet occurred about 1 billion years ago, which might rule out the chances of engulfment. The abundance of methane in the planet's atmosphere adds another line of evidence that the planet didn't go through engulfment during the red giant phase. The study's findings have sparked debate among astronomers, with some expressing skepticism about the result that the planet was "reheated" during stellar evolution. However, the study's authors argue that the planet's survival and continued evolution after the death of its host star is a testament to the resilience of planetary systems. As the sun transitions into a white dwarf about a billion years after the red giant stage ends, the rest of the planets in our solar system will continue to orbit the dead star. The study's findings offer a preview of the fate that may await our solar system's largest planets, and highlight the importance of continued research into the dynamics of planetary systems.
