Nuclei in the Cosmos (NIC XVII)

Proposed Lunar Measurements of r-Process Radioisotopes to Distinguish the Origin of Deep-sea 244Pu

19 Sept 2023, 14:30

15m

Oral Radioactivity and meteorites Radioactivity and meteorites

Speaker

Xilu WANG

Description

The astrophysical sites where r-process elements are synthesized remain mysterious: it is clear that neutron-star-mergers (kilonovae, KNe) contribute, and some classes of core-collapse supernovae (SNe) are also possible sources of at least the lighter r-process species. The discovery of ${}^{60}$Fe on the Earth and Moon implies that one or more astrophysical explosions have occurred near the Earth within the last few Million years (Myr), probably SNe. Intriguingly, ${}^{244}$Pu has recently been discovered in deep-sea deposits spanning the past 10 Myr, a period that includes two ${}^{60}$Fe pulses from nearby supernovae. ${}^{244}$Pu is among the heaviest r-process products, and we consider whether it was created in the supernovae, which is disfavored by nucleosynthesis simulations, or in an earlier kilonova event that seeded ${}^{244}$Pu in the nearby interstellar medium that was subsequently swept up by the supernova debris. We discuss how these possibilities can be probed by measuring ${}^{244}$Pu and other r-process radioisotopes such as ${}^{129}$I and ${}^{182}$Hf, both in lunar regolith samples returned to Earth by missions such as Chang'e and Artemis, and in deep-sea deposits.

Presentation materials

3. NIC2023_xwang.pptx