It’s the end of the world, not quite as we know it.
Scientists of the University of Warwick and other universities are studying the impact that white dwarfs – end-of-state stars that have burned through all their fuel – have on planetary systems like our own solar system.
When asteroids, moons and planets come close to white dwarfs, their great gravity tears these tiny planetary bodies into smaller and smaller pieces, which continue to collide and eventually grind them into dust.
While the researchers said Earth will likely be swallowed up by our host star, the Sun, before it becomes a white dwarf, the rest of our solar system, including asteroids between Mars and Jupiter, as well as moons of Jupiter, could eventually be shredded by the sun in a white star form.
Dr Amornrat Aungwerojwit of Naresuan University in Thailand, who led the study, said: “Previous research has shown that when asteroids, moons and planets come close to white dwarfs, the great gravity of these stars breaks these small planetary bodies into smaller and smaller pieces tear.”
Collisions between these pieces eventually grind them into dust, which eventually falls into the white dwarf, allowing researchers to determine what type of material the original planetary bodies were made of.
Prof Boris Gaensicke, from the Department of Physics at the University of Warwick, said: “The simple fact that we can detect debris from asteroids, perhaps moons or even planets orbiting a white dwarf every few hours is quite amazing. , but our study shows that the behavior of these systems can evolve rapidly, within a few years.
“While we think we are on the right track in our studies, the fate of these systems is much more complex than we could ever imagine.”
For the new research, scientists examined changes in the brightness of stars for 17 years and shed light on how these bodies are disrupted. They focused on three different white dwarfs, all of which behaved very differently.
The first white dwarf studied – known as ZTF J0328-1219 – appeared stable and “well-behaved” over the last few years, but the authors found evidence for a major catastrophic event around 2010.
Another star – known as ZTF J0923+4236 – has been shown to dim irregularly every few months, showing chaotic variation on timescales of minutes during these dimmer states, before brightening again.
The third white dwarf analyzed – WD 1145+017 – was shown by Massachusetts Institute of Technology (MIT) in 2015 to behave close to theoretical predictions, with large variations in numbers, shapes and depths of transits. Surprisingly in this latest study the transits are now completely gone.
“The system generally brightens very slightly as the dust produced by catastrophic collisions around 2015 dissipates,” Gaensicke said. “The unpredictable nature of these transits can drive astronomers crazy – one minute they’re there, the next they’re gone. And that indicates the chaotic environment they are in.”
When asked about the fate of our own solar system, Gaensicke said: “The sad news is that Earth will probably just be swallowed up by an expanding sun before it becomes a white dwarf.
“For the rest of the solar system, some of the asteroids located between Mars and Jupiter, and perhaps some of Jupiter’s moons, could become dislodged and move close enough to the eventual white dwarf to undergo the fragmentation process we investigated.”
This study is published in the journal Monthly Notices of the Royal Astronomical Society (MNRAS).
