[P-PS06] Planetary Sciences

[PPS06-16] Cosmic-Ray Bath in a Past Supernova Gives Birth to Earth-Like Planets

*Ryo Sawada¹, Hiroyuki Kurokawa¹, Tetsuo Taki¹ (1.The University of Tokyo)

Keywords:formation of the solar system, protoplanetary disks, supernovae, nucleosynthesis

A fundamental question in astronomy is the prevalence of systems that host Earth-like planets—rocky worlds with little water. One key to understanding the conditions for forming Earth-like planets is the presence of extinct short-lived radionuclides (SLRs; 10Be, 26Al, 36Cl, 41Ca, 53Mn, and 60Fe) in the solar system. Their radioactive-decay heat is considered crucial in forming rocky planets. However, no known single mechanism can simultaneously reproduce the abundance of all these SLRs. Here, we propose an ‘immersion’ scenario as the unified origin of these SLRs. Specifically, immersion of the protosolar disk in cosmic rays, confined within the shock wave of a nearby supernova, leads to 10Be and 41Ca nucleosynthesis, 36Cl, 53Mn, and 60Fe being injected from the supernova ejecta, and 26Al being sourced from both. Our immersion model shows that a supernova occurring at approximately 1 pc away can reproduce the early-solar-system abundances of all the SLRs inferred from meteorite analysis. We estimate that a solar-mass star forming in a star cluster typically experiences one nearby supernova (at ∼1 pc) during its lifetime, supporting the feasibility of the immersion scenario. This study further suggests that solar-system-like SLR abundances are common, implying that Earth-like planets may be ubiquitous in our galaxy.