A team of Polish scientists captured a rare explosion that happens around every 10,000 to one million years. The explosion itself is called a Classical Nova. Researchers were able to observe the before, during and after of the ‘classical nova’ explosion providing evidence of the unique event.

Polish astronomers, based in Chile, were performing a sky survey that intended the detection of dark matter. But they obtained much more, discovering the process of a classical nova explosion. Results are published in the science journal Nature as researchers collected images for the “Optical Gravitational Lensing Experiment“,  discovering they had a timeline that captured the rare event.

Since the team had collected several images throughout the years, they were able to observe the system before and after the eruption. Image Credit: NASA
Since the team had collected several images throughout the years, they were able to observe the system before and after the eruption. Image Credit: NASA

Back in 2009, the team of researchers led by  Ph.D. student Przemek Mróz spotted the explosion that caught their attention in first place.

“Thanks to our long-term observations, we saw the Nova a few years before and after the explosion,” said Przemek Mróz to BBC news.

What is a Classical Nova explosion?

The rare event commonly happens in a binary system, which is when two stars are orbiting each other at close range. In this case, the two stars are about the size of Earth’s sun, are distanced by one solar radius and one of them is considered a ‘white dwarf’ star.

The distance between the stars is too tight that it only takes five hours to orbit each other and start again, researchers explained. A white dwarf is a remain of a common star and is locked in an orbit cycle with a “red dwarf” which is an active and regular star.

The white dwarf tends to feed on the active star since this one is continuously transferring matter. Every 10,000 to a million years, the white dwarf has fed on so much matter that it reaches a critical point, and a thermonuclear explosion occurs, which is what the Polish astronomers observed.

NASA's Fermi Space Telescope was able to capture the exact moment of a nova, called Classical Nova. Image Credit: NASA
NASA’s Fermi Space Telescope was able to capture the exact moment of a nova, called Classical Nova. Image Credit: NASA

Previous research had estimated that when a classical nova occurs, the explosion takes place, but the system remains untouched. Nonetheless, the white dwarf stays in position minus the significant amount of matter. Since the system remains the same, the process starts all over again, and this is what scientists call the “Hypothetical hibernation theory.”

“The entire system survives the nova explosion, so the whole process starts again. After thousands of years, our Nova will awake and explode again, but no one will be able to see it,” explained lead author Mr. Mróz.

This hibernation theory supports that when a classical nova is going to occur the white dwarf star goes almost numb and stops feeding on the active star. But after the explosion, the ‘feeding’ is higher and more stable. Researchers discovered that something in the binary system had changed after the blast. And before the classical nova occurred, the mass transfer between the red dwarf and the white dwarf was little.

After the bright explosion, researchers observed the mass transfer between the stars is now bigger and also stable. Which means the binary system changed after the classical nova occurred and the hibernation theory is supported.

In another phenomenon called ‘Supernova,’ the process is similar, but the explosion is so big that the whole system collapses and disappears. According to NASA, Supernova explosions are very common in galaxies, but not on our Milky Way because dust blocks astronomer’s views.

An artist's depiction of a classical nova as seen from space. Image Credit: Phys
An artist’s depiction of a classical nova as seen from space. Image Credit: Phys

The last Supernova explosion was observed in 1604 by astronomer Johannes Kepler in the Chandra telescope, discovering the remains of an explosion that had happened hundred of years before.

What does the discovery mean for astronomers?

If the Polish team is right, this would be the first time the hibernation theory is spotted and supported by graphic evidence, which would mark a before and after in astronomy and confirm the long-discussed theories.

The discovery has stimulated a conversation between astronomers from around the world, as BBC reports, an astronomer from the Southhampton University believes is still too early to make assumptions.

The scientist Christian Knigge assured the explosion is still cooling down, and the end of the outburst is still happening, so more time is needed as well as more evidence on the subject. However, the astronomer assures preliminary evidence is leading to the hibernation theory, but only time will tell.

“I would say it is the best hypothesis we have, it is somewhat controversial, but no one has proposed anything equally good,” said Polish lead-author, Mróz, ” We’re not saying that our observations confirm a hibernation scenario, but the are in accord with predictions,” said the P.h.D.

Source: Nature