Astrophysicists have just pulled off a remarkable cosmic detection work, confirming the existence of a rare stellar system, which has long been speculated but never directly observed. They’ve traced a high-mass double white dwarf binary system on a collision course with one another, whose eventual fate is to explode as a type 1a supernova. Astronomers predict that the explosion, in the future, will shine ten times brighter than the Moon.
The type 1a supernova is quite an infrequent cosmic explosion, occurring only once in about 500 years. They occur when a white dwarf accumulates too much mass from the companion star and is then unable to withstand its own gravity, eventually triggering an explosion.
The double white dwarf binaries have long been considered a suitable candidate to study type 1a supernova. Now, researchers have confirmed the existence of such a binary star system just about 150 light years away, and intriguingly, right in the Milky Way.
Researcher at Warwick and leader of the investigation, James Munday, said, “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.”
Researchers quickly resorted to some of the biggest optical telescopes in the world to measure just how tight the binary system is. They discovered that the two stars are separated by just 1/60th of the distance between Earth and the Sun.
“I quickly realised that we had discovered the first double white dwarf binary that will undoubtedly lead to a type 1a supernova on a timescale close to the age of the universe,” said Munday.
With a combined mass of 1.56 times that of the Sun, James’ new pair system is the heaviest of its kind ever confirmed. Given the highly unstable mass, researchers assert that an explosion is inevitable. However, the explosion is not expected to occur for another 23 billion years, and even then, the cosmic event poses no threat to Earth.
Currently, the white dwarfs complete an orbit in roughly 14 hours. But, as gravitational waves drain their energy for billions of years, the duo will gradually lose orbital angular momentum, shortening the period to a mere 30 – 40 seconds.
Looking ahead to the explosion when supernova occurs, the event will transfer mass from one dwarf star to another. This will result in a complex supernova explosion through quadruple detonation (four explosions). Initially, the mass-gaining dwarf detonates, causing its core to blow up next. This explosion ejects matter in all directions, which collides with the companion white dwarf, triggering two more detonations.
The blast will release energy a thousand trillion times that of a nuclear bomb, which will ultimately eradicate the entire system.
This type 1a supernova will appear as a beam of light in the sky and may outshine some of the brightest objects, appearing 200,000 times as bright as Jupiter.
The research was published in Nature Astronomy.