Two dwarf stars spotted that could explode in 22 billion years!

Astronomers have spotted two huge white dwarf stars which they say are destined to explode together in a supernova.

This is because of how close together the stars are, and it's the first time something like this has been seen and identified

When it happens, from Earth it would appear about 10 times brighter than the moon in the night sky.

But it's not something we need to worry about, as researchers calculate that it will take place approximately 22.6 billion years from now.

The two stars are part of our Milky Way galaxy and are about 160 light-years from Earth.

A light-year is the distance light travels in a year - 5.9 trillion miles, or 9.5 trillion km.

This means that although the stars are relatively close in space terms, they're still very very far away!

In fact experts aren't even sure if Earth, which is currently about 4.5 billion years old, would definitely still exist then.

What is a dwarf star?

White dwarfs are among the most compact objects in the sky. They are stars with up to eight times the mass of our sun. Mass is a measure of how much matter there is in an object

Because their mass will become so big, gravity will cause them to collapse and blow off their outer layers in a "red giant" stage, eventually leaving behind a compact core roughly the same size around as the Earth.

Why will the stars explode?

One of the reasons is because of how big these particular dwarf stars are.

Researchers used data from four telescopes to study them, and found that one of the white dwarfs has a mass about 83% that of our sun and the other about 72%.

James Munday, a PhD researcher at the University of Warwick is the lead author of the study published in the journal Nature Astronomy.

He said that no other known white dwarf has a larger combined mass.

"They are both about as big as the Earth," he explained. "Their masses when they were regular stars were probably around three to four times the mass of the sun." So they were pretty big!

The white dwarf stars are part of the Milky Way galaxy

The other reason is because of how close the two huge dwarf stars are to each other.

They are about 25 times closer to each other than our solar system's innermost planet Mercury is to the sun, completing an orbit every roughly 14 hours.

James added: "From time to time we find systems where two white dwarfs closely orbit each other.

"In a wider orbit, they could indeed live stably without any catastrophic future, but here we know that the explosion will light up our side of the galaxy."

What will happen to these two dwarf stars?

Another researcher on the team Pelisoli explained: "White dwarfs are made up of layers, much like an onion. Their inner layer is a core of carbon and oxygen, surrounded by a helium layer and finally by a hydrogen layer."

When they get closer to each other, the heavier of the two white dwarfs will begin to draw material from the lighter one's outer layer and increase in mass because of its greater gravitational strength.

This will cause a chain of events which will cause 4 different explosions. These explosions are expected to take about four seconds, start to finish. That will be a big bang!