Violent stellar collision near early solar system created actinides

The collision of two giant dead stars 4.7 billion years ago created most of the curium and plutonium that has ever existed in the solar system. This new finding goes against previous studies that suggested that frequent supernovae have produced a constant stream of radioactive heavy elements.

Most elements are produced inside stars through nuclear fusion. But for elements heavier than iron, this process becomes inefficient, requiring more energy than it releases.