2023ApJ...948..113W

²⁴⁴Pu has recently been discovered in deep-sea deposits spanning the past 10 Myr, a period that includes two ⁶⁰Fe pulses from nearby supernovae. ²⁴⁴Pu is among the heaviest r-process products, and we consider whether it was created in supernovae, which is disfavored by nucleosynthesis simulations, or in an earlier kilonova event that seeded the nearby interstellar medium with ²⁴⁴Pu that was subsequently swept up by the supernova debris. We discuss how these possibilities can be probed by measuring ²⁴⁴Pu and other r-process radioisotopes such as ¹²⁹I and ¹⁸²Hf, both in lunar regolith samples returned to Earth by missions such as Chang'e and Artemis, and in deep-sea deposits.