Astronomers have captured rare images of a tiny star before, during and after it exploded as a “classical nova“.
These violent but poorly understood events begin with a white dwarf, the dead remnant of an average star like our Sun, is locked in tight orbit with a regular, active star.
“The distance between those two stars is very small – actually one solar radius,” Mr Mróz said. “Imagine that inside the Sun, you have two stars that are orbiting each other.”
So tight is their orbit, which in this case takes just five hours, that the dwarf steadily steals gas from its larger companion.
That extra matter builds up on the surface of the white dwarf until it kicks off a runaway, explosive thermonuclear reaction. Crucially, however, this blast only rips off the extra material; the white dwarf is left behind.
“That means that the explosion we observed changed the properties of the binary.”
In fact, Mr Mróz and his colleagues argue that their results support a “hibernation” model for classical novae. This means that during the lengthy wait between explosions, the system goes almost completely dark and the white dwarf stops stealing gas altogether.
That model predicts a slow, sputtering transfer of matter between the stars before the explosion, and a relatively fast and bright transfer afterwards – which is precisely what the Polish researchers believe they have captured.
Other astronomers are less convinced.
“The thing is still just cooling down at the moment – it’s not yet steady. So we don’t yet know what the long-term brightness is going to be, post outburst, because really we’re still seeing the end of the outburst,” commented Christian Knigge from the University of Southampton.
Like any scientist, anywhere – he wants to see more data.
“This is very circumstantial,” Prof Knigge told BBC News.
But he added: “As observations, as a test bed for our theories of how these explosions work – this really is fantastic.
“We can really measure what the brightness and the conditions were before the eruption; we can use this to inform how we model the eruption; we have a nice measure of how long it takes to decline – and we’re going to keep following this.
“I do think this data is going to shed light on classical nova theory – but from my perspective it’s too early to claim that this is a clear case of a hibernating system that’s now erupted.”