For the first time, a team of scientists have captured all phases of a classical nova explosion — before, during, and after the event. The event took place back in 2009, but at first the astronomers didn’t even realize they’d captured such an unusual occurrence. After going back and looking at the data, they spotted the nova and have now published the paper in the journal Nature.
You hear a lot more about supernovas because that’s something that many stars will go through eventually. That’s the explosion that kicks off the final stage in stellar evolution. It occurs when a massive star has exhausted its supply of fusion elements and can no longer support its own gravity. It collapses and causes a massive explosion. What’s left afterward is a stellar remnant — a neutron star, black hole, or white dwarf. Our sun will most likely become a white dwarf at the end of its life.
A nova, on the other hand, does not signal the death of a star and is much more rare. It occurs when a star of some sort collects material from a nearby companion. This increases the mass of the star and eventually results in a huge thermonuclear explosion. This can happen with various star types, but it’s most common when there’s a compact and highly dense stellar remnant in close proximity to a star still has not gone supernova. In the case of this observation, known as Nova Centauri 2009, researchers saw a white dwarf go nova after accreting matter from its binary companion red dwarf.
The astronomers were working with the Warsaw University Observatory on a completely different observation when they spotted the nova explosion. After that, they went back and looked at past images of that area of the sky, finding that the entire build-up had been captured in addition to the explosion and aftermath.
Studying the wealth of data, the researchers were able to see fluctuations in brightness as mass was being transferred to the white dwarf in the days leading up to the nova. They also watches as the rate of mass transfer shot up immediately following the explosion. The study states that the system is still brighter than it was before the nova, but it’s continuing to fade. Having a timeline of observational data leading up to the nova could allow astronomers to learn more about how these binary systems behave. It is believed that novas in systems like this one only occur every few million years, so it was lucky we were looking in the right place at the right time.
Now read: What is a supernova — or why stars explode, creating the universe as we know it