Astronomers captured the first timelapse images of a thermonuclear fireball exploding out of a nova star enabling them to observe the whole event as it occurred.
An international team of researchers collaborated from University of Sydney’s Institute for Astronomy with the Georgia state university scientists who run the Centre for High Angular Resolution Astronomy (CHARA) array in Southern California and who were also able to make the fine measurements necessary to map the event.
Novae happen when an exotic dense star commonly referred to as a white dwarf absorbs the matter from a nearby companion star with its intense gravitational field.
The white dwarf continuously absorbs hydrogen from its companion , forming an ocean on its surface and after drawing about as much mass as Saturn , the pressure reaches a threshold which follows a huge explosion and the entire stellar surface turns into one humungous hydrogen bomb hurling a fireball out into space and propelling a formerly dim, obscure star system into prominence as a nova in our night skies.
The level of the expansion was enthralling , covering the size of the Earth’s orbit within a single day and encompassing Jupiter’s orbit in less than two weeks.
A lot of special technology was involved to image the whole event. The array was able to produce the first pictures of a nova at the early fireball stage which actually occurred 15,000 years ago, but the star is 14,800 light years from our Sun.
The observations recorded were quite insightful as it showed how the structure of the ejected material evolves as the gas expands and then cools. Initially the fireball was roughly the size of the Earth’s orbit but after 43 days , it had expanded nearly 20 times to the size of Neptune’s orbit. This also revealed that the explosion was not entirely spherical rather the fireball was more elliptical in nature. It was also observed that the outer cooler layers were more brighter especially due to dust grains which emitted light at infrared wavelengths.
This finding depicts that the actual expansion of the fireball is more complicated than previously predicted and the most astonishing thing is , despite the severity of the detonation , the star emerges almost in its entirety.