Our solar system might be pulled into the gravity of a white dwarf star, crushed and ground to dust, according to scientists from the University of Warwick.

Astrophysicists from Warwick and other universities have helped to answer what happens to planetary systems, like our solar system, when their host stars become white dwarfs. Our host star is the Sun.

White dwarfs are the end state of stars when they have burned all their fuel, offering insight into different aspects of star formation and evolution.

In the study researchers investigated the fate of asteroids, moons and planets which pass close to the white dwarfs, by analysing transits – which are dips in the brightness of stars caused by objects passing in front of them.

Unlike the predictable transits caused by orbiting planets around stars, transits caused by debris are oddly shaped, chaotic and disorderly. This suggests the fate of these bodies to be extremely catastrophic and violent.

Dr Amornrat Aungwerojwit of Naresuan University, who led the study, said: “Previous research had shown that when asteroids, moons and planets get close to white dwarfs, the huge gravity of these stars rips these small planetary bodies into smaller and smaller pieces.”

Collisions between these pieces eventually grind them into dust, which finally falls into the white dwarf, enabling researchers to determine what type of material the original planetary bodies were made from.

In this new research, scientists investigated changes in brightness of stars for 17 years, shedding insight into how these bodies are disrupted. They focused on three different white dwarfs which all behaved very differently.

Professor Boris Gaensicke, Department of Physics, University of Warwick, commented: “The simple fact that we can detect the debris of asteroids, maybe moons or even planets whizzing around a white dwarf every couple of hours is quite mind-blowing, but our study shows that the behaviour of these systems can evolve rapidly, in a matter of a few years.

“While we think we are on the right path in our studies, the fate of these systems is far more complex than we could have ever imagined.”

The first white dwarf (ZTF J0328−1219) studied appeared steady and “well behaved” over the last few years, but the authors found evidence for a major catastrophic event around 2010.

Another star (ZTF J0923+4236) was shown to dim irregularly every couple of months, and shows chaotic variability on time scales of minutes during these fainter states, before brightening again.

The third white dwarf analysed (WD 1145+017), had been shown by Massachusetts Institute of Technology (MIT) in 2015 to behave close to theoretical predictions, with vast variations in numbers, shapes and depths of transits. Surprisingly in this latest study, the transits are now totally gone.

“The system is, overall, very gently getting brighter, as the dust produced by catastrophic collisions around 2015 disperses”, said Professor Gaensicke. “The unpredictable nature of these transits can drive astronomers crazy – one minute they are there, the next they are gone. And this points to the chaotic environment they are in.”

When asked about the fate of our own solar system, Professor Gaensicke, said: “The sad news is that the 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 maybe some of the moons of Jupiter may get dislodged and travel close enough to the eventual white dwarf to undergo the shredding process we have investigated.”

This study is published today in the journal Monthly Notices of the Royal Astronomical Society (MNRAS).

Read the paper here: https://academic.oup.com/mnras


Notes to Editors

Images:



Caption: Clumps of debris from a disrupted planetesimal are irregularly spaced on an long and eccentric orbit around the white dwarf. Individual clouds of rubble intermittently pass in front of the white dwarf, blocking some of its light. Because of the various sizes of the fragments in these clumps, the brightness of the white dwarf flickers in a chaotic way.

Credit: Dr Mark Garlick/The University of Warwick

Contact details:

To speak to University of Warwick collaborators contact Annie Slinn, Communications Officer, University of Warwick. Tel: +44 (0)7392 125 605 Email: annie.slinn@warwick.ac.uk


Naresuan University contact: Dr Sukuny Ross, sukunyaj@nu.ac.th


9 April 2024