Speaker
Description
Chlorine (Cl) and potassium (K) are essential elements for life, yet their cosmic origins remain poorly understood. Current Galactic chemical evolution models underestimate the production of Cl and K by up to an order of magnitude (e.g., Kobayashi et al. 2020). However, these light odd-Z elements have not been clearly detected at their production sites, preventing direct observational tests of their nucleosynthetic origins. Here, we present X-ray observations of the core-collapse supernova remnant Cassiopeia A, led by XRISM/Resolve. For the first time in the X-ray band, we detect Cl and K, together with a possible signature of P, alongside neighboring even-Z elements (XRISM Collaboration 2025). Notably, we measure a K/Ar abundance ratio 1.2–1.3 times the solar value, indicating efficient production of odd-Z elements in this event. Such yields are expected to depend on progenitor properties, including rotation (Limongi et al. 2018), as well as dynamic stellar-evolution processes such as shell mergers (Ritter et al. 2018; Issa et al. 2026). In this presentation, we will present XRISM/Resolve results in combination with complementary observations from previous X-ray missions, and discuss their implications for nucleosynthesis in Cassiopeia A.
| Category | Observation |
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