How Do White Dwarf Stars Shred Planets?

Though we know this is the fate of our star, what of the planets in our Solar system? But what exactly will happen to Earth long after we're gone. Astronomers from the University of Warwick in the UK took a stab at answering this question back in twenty nineteen and came up with a rudimentary warning guide for planets that

find themselves in this grim scenario. While our planet's fate isn't necessarily clear, the study, which is published in the journal Monthly Notices of the Royal Astronomical Society, revealed that when it comes to contending with a white dwarf star, only the tiniest worlds will survive. Why is that, Well, we know that many white dwarf star systems have quantities of dust surrounding them, and through spectroscopic measurements, dust has

been found polluting these star's atmospheres. The implication is clear. These star systems used to have rocky planets, plus asteroids and comets and orbit, but through extreme tidal interactions with their white dwarf, were torn to shreds and ground to dust. But why do planetary bodies get blended when they're in the orbit of a white dwarf. These exotic stellar objects contain nearly the entire mass of the dead star that they came from, in a blob of degenerate matter only

the size of Earth. With this extreme density comes an incredibly powerful gravitational field and tidal forces. Anything that strays too too close to a white dwarf will be pulled in by that powerful gravity. But there's a much wider zone of destruction around such a star within which planets

or other orbiting bodies will be destroyed. Within this zone, a planet, for example, will experience a much more powerful tidal force on the star facing side than on the side facing away, depending on what that planet is made of and how well it holds together due to its own gravity and a number of other factors. At a certain distance, the tidal shear through the planet will be too much, and it will be literally pulled like taffy

until it's pulled right apart. This is known as the destruction radiusmarked by an ominous dusty ring around a white dwarf. To understand where a variety of planets of different sizes might be safe, the researchers carried out dynamic simulations of different planets in orbit around a star like our Sun, as it dies and passes through the red giant phase

to become a white dwarf. This violent phase of a star's life will disturb the orbit of the planets around it, possibly dragging them to their dusty deaths or flinging them to wider orbits. Interestingly, the researchers found that it isn't just the mass and composition of planets that affect how sensitive they are to the tidal shear. It's also their

viscosity or the resistance they have to being deformed. Think if you had a glass of water and a glass of nacho cheese, If you poked the surface of the water, it would easily deform around your finger. You'd feel basically no resistance at all. This is low viscosity. Now, if you poked the nacho cheese, I mean, you'd still be able to deform its surface, but it would give you a little bit more resistance because it has a higher viscosity. Now, think about if you poke the glass itself, It's not

going to deform at all from a mere poking. Of the three, it has the highest viscosity under these particular circumstances. Anyway,

the physics is complicated. But back to white dwarfs. The researchers found that if all other variables were controlled for low viscosity, exoplanets of a similar consistency to say, Saturn's moon Enceladus, which they called a relatively homogeneous dirty snowball because of its thick iso layers surrounding a small core, would be dragged to its doom if it resides within anywhere up to five times of the white dwarf's destruction radius.

At the other extreme, a high viscosity world might live comfortably if it orbited the white dwarf at just twice its destruction radius. Recently, astronomers discovered a dense, heavy metal object around a white dwarf that's embedded inside a dusky disc. It's believed that this object, which isn't much bigger than a large asteroid, was the metal core of a larger planet that was destroyed by tidal shear, leaving its high

viscosity metallic core behind. As the search for exoplanets, that is planet's orbiting other stars becomes more sophisticated, we're going to observe more worlds in white dwarf star systems, So the researchers hope that these simulations will act as a guide that will help us understand what those exoplanets are made of. Although this simulation has provided some key insights to what it takes to avoid being dragged to a

dusty death, it only simulated relatively homogeneous objects. When it comes to our planet, the problem becomes more complex because of all the layers of atmosphere, water, rock, and inner metallic core that our planet contains. But in summary, it pays to be tiny and mighty and composed of heavy metals if you want to have a snug orbit around a white dwarf without being dragged to your death. As for Earth's fate, we'll have to wait and see, but in all honesty, you probably won't want to be there

when our red giant sun switches to broil. A note that long before the Sun runs out of hydrogen and puffs up into a red giant let alone before it becomes a white dwarf, it will become a lot hotter than it is now, irradiating the inner planets. This, combined with powerful solar winds, will likely blast away our atmosphere,

undoubtedly destroying any and all life that remains. So today's episode is based on the article white dwarfs can shred planets to pieces on HowStuffWorks dot com, written by Ian O'Neil. Brainstuff is production of iHeartRadio in partnership with hostuffworks dot Com and is produced by Tyler klang A. Four more podcasts from my heart Radio visit the iHeartRadio app, Apple Podcasts, or wherever you listen to your favorite shows