Astronomers have discovered two white dwarf stars hurtling towards a violent explosion. Located 160 light-years from Earth within the Milky Way galaxy, these stellar remnants are destined for four explosive detonations. The discovery offers a glimpse into the dramatic fates awaiting some of the universe’s most fascinating objects.
White dwarfs represent the final stage of evolution for stars up to eight times the mass of our sun. After exhausting their hydrogen fuel, they collapse under their own gravity, shedding their outer layers in a “red giant” phase. What remains is an incredibly dense core, roughly the size of Earth – a white dwarf.
The two white dwarfs in this binary system are gravitationally bound, spiraling ever closer. This proximity sets the stage for a cataclysmic event. As they draw nearer, the immense gravitational forces will trigger a series of explosions, culminating in a final, powerful detonation.
Researchers used data from four ground-based telescopes to study this binary system. One white dwarf has a mass about 83% that of our sun and the other about 72%. No other known white dwarf binary has a larger combined mass.
“Their masses when they were regular stars were probably around three to four times the mass of the sun,” said University of Warwick astrophysicist Ingrid Pelisoli. “They are both about as big as the Earth, with one having a diameter 20% larger and the other 50% larger.”
As the binary system loses energy, the fact that they are so massive and so close ensures their demise over a large timescale. When they get closer to each other, the heavier white dwarf will begin to draw material from the lighter one’s outer layer, increasing in mass past the threshold beyond which a white dwarf experiences a thermonuclear explosion.
This will set the stage for a complex explosion called a type 1a supernova, involving a quadruple detonation. The quadruple detonation is expected to occur approximately 22.6 billion years from now and will appear from Earth about 10 times brighter than the moon in the night sky.
This discovery marks the first time a binary system apparently headed for such a fate has been identified. If the two white dwarfs were far enough apart, they could survive in perpetual peace. However, their close proximity guarantees a catastrophic future, with the explosion lighting up our side of the galaxy.
Source: https://www.independent.co.uk/space/white-dwarf-star-explosion-astronomy-b2729559.html