17 dead stars ignited ahead of schedule. The ZTF telescope, named after astronomer Fritz Zwicky, caught their faint light in the first hours after the explosion. Astronomers had long suspected that a thermonuclear explosion of a white dwarf (an ultra-dense star remnant the size of Earth) could produce a short precursor — like a smoldering fuse before a firework. But capturing it only succeeded now, after sifting through thousands of candidates and keeping 1792 reliably observed in early stages.
It turned out that such impatient stars live in galaxies with many young stars. That means the second star in the pair was massive and short-lived. Scientists tested two ignition scenarios. First: helium ignites on the surface first, and the shockwave detonates carbon in the core. Second: an ejection hits the companion star. The data agrees better with the first scenario, but it's not certain yet. If we can measure this fuse, we'll know distances in the Universe more accurately.
The brightest excess among the candidates, in supernova ZTF18abxxssh, was spotted less than a day after the last non‑detection. Its early brightness in the first two days exceeded expectations by 10%, as if the star decided to announce itself in advance.
In Arthur C. Clarke's novel 'Rendezvous with Rama', a supernova is used as a beacon for interstellar navigation. An early excess could serve as a more precise trigger for spacefaring civilizations — a sort of warning signal a few days before the blinding flash.