A Nearby Supernova: Recipe for Rocky Planets express
Just as yeast transforms flour into airy dough, a radioactive 'seasoning' from a supernova helps mold a rocky planet. But the dosage must be perfect: too much and the disk of cosmic dust gets blown away; too little and the planet remains loose and cold. Previously, it was thought that the explosion had to be so close that it would inevitably destroy the embryonic planetary system. However, new research has revealed an elegant trick: its invisible rays pierce the disk, collide with matter, and fabricate radioactive aluminum-26 right on the spot. At a distance of one parsec (about the distance to Proxima Centauri), the disk is not destroyed but instead receives exactly the amount of aluminum-26 found in meteorites. Calculations show that in typical stellar nurseries, at least one supernova is located at this distance. This means the recipe for forming exoplanets like Earth is not a cosmic fluke: it's the rule. The heat from aluminum-26, which has a half-life of just 717,000 years, melts the interior and separates the planet into core and crust. Perhaps this is exactly how our Earth came to be.
Original abstract
as written by the authors arXiv:2512.09660
A key question in astronomy is how ubiquitous Earth-like rocky planets are. The formation of terrestrial planets in our solar system was strongly influenced by the radioactive decay heat of short-lived radionuclides (SLRs), particularly $$^{26}$$Al, likely delivered from nearby supernovae. However, current models struggle to reproduce the abundance of SLRs inferred from meteorite analysis without destroying the protosolar disk. We propose the `immersion' mechanism, where cosmic-ray nucleosynthesis in a supernova shockwave reproduces estimated SLR abundances at a supernova distance ($$\sim$$1 pc), preserving the disk. We estimate that solar-mass stars in star clusters typically experience at least one such supernova within 1 pc, supporting the feasibility of this scenario. This suggests solar-system-like SLR abundances and terrestrial planet formation are more common than previously thought.
The heat from aluminum-26 melted the first asteroids, giving them a core and crust, like miniature Earths long before planets were born.