Ever wonder what our sun will look like in a few billion years? Or what our planet and the entire solar system has in store? Sure, it won’t happen in our lifetime, but because of the planet-like object scientists have discovered orbiting a white dwarf star, we can take a look at what our solar system will look like in about 5 billion years.
It’s been common in the last few decades to find planets beyond our own solar system orbiting stars. Just like our sun, these solar systems have main-sequence stars that get their energy from core nuclear reactions. When these stars run out of fuel, they become red giants.
When our sun begins this process, it will consume Mercury, Venus, and most likely Earth, as well, and expand into the solar system. Once the core collapses, it becomes a white dwarf, too. For those of you who may not know, a white dwarf is an extremely dense, faint star that’s about the size of a planet.
Planets that orbit white dwarfs gradually move closer to the star until they collide, smash, and become floating debris.
Christopher Manser, of the U.K.’s University of Warwick, published a study done with his colleagues in Science. They presented evidence of a small, intact planetary body orbiting the white dwarf SDSS J122859.93+104032.9.
“The gaseous planetary disc around this white dwarf was the first discovered, and is currently still the brightest disc known, making it great for observations,” Manser told Newsweek. “The observations were taken as a pilot test to see if we could detect anything happening on the time it takes material to orbit the white dwarf (roughly hours).”
The team was astonished to discover a planetesimal, which is a solid object formed through colliding rocks that have clumped together. The only way it wasn’t torn apart by the white dwarf’s gravitational pulls was because it was 370 miles in diameter and very dense. They’ve surmised that this planetesimal could be the core of one of the solar system’s planets.
“To survive so close to the white dwarf, the body either has to have a large density, or a high internal strength to avoid being ripped apart,” Manser said. “Currently, we cannot distinguish between the two, only that it requires some minimal amount of internal strength and a density around that of iron—if the internal strength is greater, our density estimate can be reduced.”
Scientists are fascinated to see a glimpse into the destiny of our own solar system. It seems as though the three inner planets will be destroyed while the rest stay intact.
“By studying systems like SDSSJ122859.93+104032.9, we can learn more about the future of the solar system, and the majority of all known exoplanetary systems, which orbit stars that will themselves eventually become white dwarfs,” Manser said. He also mentioned they plan to find more planetesimals like this one.
A professor in University College London’s physics and astronomy department who was not involved in the study, Jay Farihi, said the planetesimal was similar to a “ring moon”—an object orbiting in the disc of rock and dust surrounding the star.
“This likely means the disks or rings around white dwarfs are highly dynamical and changing environments that will continue to do interesting things and elucidate more exoplanetary science,” he said.
“Continued monitoring of these real-time events should give insight into the total masses of the rings, the planetary parent bodies that were disrupted or otherwise destroyed to create the dust and gas, and most of all how they compare to Earth and the terrestrial planets.”