Romeo and Juliet were a pair of doomed, star-crossed lovers. Now, astronomers have detected a pair of doomed star-crossed stars. Like Shakespeare’s famously unlucky couple, two white dwarfs spiraling around each other are on a course toward destruction.
Astronomers discovered that the stellar partners are separated by a distance of 1/60th — the difference between the Earth and the sun, they report in Nature Astronomy. This proximity will eventually destroy them.
Stellar Collision Course to Supernova
When gravity pulls them together they will explode as a type 1a supernova. This rare form of cosmic explosion is thought to be triggered when a white dwarf builds up too much mass, then falls victim to its own gravity. Astronomers have long theorized that two orbiting white dwarfs are the root of most type 1a supernova explosions.
This is the first sighting of such a phenomenon. Although astronomers had long predicted it, actually witnessing it provided a thrill.
“For years a local and massive double white dwarf binary has been anticipated, so when I first spotted this system with a very high total mass on our Galactic doorstep, I was immediately excited,” James Munday, a University of Warwick researcher and an author of the study, said in a press release. “With an international team of astronomers, four based at The University of Warwick, we immediately chased this system on some of the biggest optical telescopes in the world to determine exactly how compact it is.”
The short answer? It’s pretty compact.
Read More: White Dwarf Star Explosions May Offer Clues on Dark Energy
Stars Destined to Explode
The system represents the heaviest of its type ever confirmed. The two stars have a combined mass 1.56 times that of our Sun. With two stars with that much mass so close to each other, the stars are “destined to explode,” according to the press release.
We should be safe from that eruption though, for two reasons. First, even though the system, at about 150 light years away from Earth, is considered relatively close in cosmic terms, we should be well outside the blast zone. Second, it’s not predicted to happen for about another 23 billion years.
Still, when it happens, it should produce quite a bang. The astronomers predict a blast with the force of a thousand trillion trillion times that of a nuclear bomb. It almost goes without saying that’s enough power to destroy everything within the binary star system.
But there will be a long, slow, leisurely stellar dance before that detonation. The two white dwarfs now orbit each other in about 14 hours. That rate will incrementally increase over billions of years. Eventually, that process will take about 30 seconds to 40 seconds.
A Quadruple Detonation
At that point, their proximity and gravitational pull will have sped up the dance significantly. Once the two stars get to the point of no return, mass will shift from one white dwarf to the other. That will initiate not one, but four explosions — a quadruple detonation.
First, the star gaining the mass will see its surface explode. Its core will go off next. Those events will fling material in all directions, triggering the same double bang in the other white dwarf.
If there’s anyone around to witness the event, they will see light up to ten times as bright as the Moon and 200,000 times brighter than Jupiter.
Even though, like the ending of “Romeo and Juliet” the stars’ demise is quite predictable, that shouldn’t detract from the drama.
Read More: A Failed Star can Form Brown Dwarf Stars, Which Host Their Own Planetary Systems
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Before joining Discover Magazine, Paul Smaglik spent over 20 years as a science journalist, specializing in U.S. life science policy and global scientific career issues. He began his career in newspapers, but switched to scientific magazines. His work has appeared in publications including Science News, Science, Nature, and Scientific American.
