【Research Highlights】 Ryugu’s Parent Body Formed Earlier Than the Parent Bodies of Other Carbonaceous Chondrites

A paper entitled “The parent bodies of Ryugu and Ivuna formed before those of other carbonaceous chondrites”, authored by Associate Professor Noriyuki Kawasaki, a former member of the Astromaterials Science Research Group and currently affiliated with Hokkaido University, has been published in the journal Science.

By analyzing chromium isotopes in carbonate minerals contained in Ryugu particles (A0058 and C0002) allocated to the initial analysis team, the researchers found that these minerals formed through aqueous alteration as early as approximately 2 million years after the formation of CAIs (calcium-aluminum-rich inclusions), the oldest solid materials in the Solar System. This age predates the formation ages of chondrules found in other carbonaceous chondrites and suggests that Ryugu’s parent body was among the earliest bodies in the Solar System, having formed before the parent bodies of other carbonaceous chondrites.

Original article:

Journal：  Nature
Title：  The parent bodies of Ryugu and Ivuna formed before those of other carbonaceous chondrites
Author：  Kawasaki, N. et al.
DOI：  doi.org/ 10.1126/science.adw4498
URL：  https://doi.org/10.1126/science.adw4498
Available online：  September 10, 2026

Press Release: Hokkaido University:
https://www2.sci.hokudai.ac.jp/faculty/wp/wp-content/uploads/2026/09/260911_pr2.pdf