Tetsuya Yokoyama

The parent bodies of Ryugu and Ivuna formed before those of other carbonaceous chondrites

Most carbonaceous chondrite (CC) meteorites contain abundant chondrules, millimeter-scale spherical inclusions of previously molten material. Ivuna-type carbonaceous chondrites (CIs) do not contain chondrules, nor do samples of the carbonaceous asteroid Ryugu. CIs and Ryugu share...

Ryugu and Bennu preserve primordial isotopic heterogeneity absent from the meteorite record

Ivuna-type (CI) carbonaceous chondrites are commonly used as proxies for the composition of the planet-forming disk because their chemical abundances resemble those of the solar photosphere. However, their isotopic uniformity may reflect pervasive alteration and isotopic averagin...