Hisashi Homma
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View article: The Ni isotopic composition of Ryugu reveals a common accretion region for carbonaceous chondrites
The Ni isotopic composition of Ryugu reveals a common accretion region for carbonaceous chondrites Open
The isotopic compositions of samples returned from Cb-type asteroid Ryugu and Ivuna-type (CI) chondrites are distinct from other carbonaceous chondrites, which has led to the suggestion that Ryugu/CI chondrites formed in a different region…
View article: Pyrrhotites in asteroid 162173 Ryugu: Records of the initial changes on their surfaces with aqueous alteration
Pyrrhotites in asteroid 162173 Ryugu: Records of the initial changes on their surfaces with aqueous alteration Open
View article: Disequilibrium oxygen isotope distribution among aqueously altered minerals in Ryugu asteroid returned samples
Disequilibrium oxygen isotope distribution among aqueously altered minerals in Ryugu asteroid returned samples Open
Oxygen 3‐isotope ratios of magnetite and carbonates in aqueously altered carbonaceous chondrites provide important clues to understanding the evolution of the fluid in the asteroidal parent bodies. We conducted oxygen 3‐isotope analyses of…
View article: Hydrogen in magnetite from asteroid Ryugu
Hydrogen in magnetite from asteroid Ryugu Open
In order to gain insights on the conditions of aqueous alteration on asteroid Ryugu and the origin of water in the outer solar system, we developed the measurement of water content in magnetite at the micrometer scale by secondary ion mass…
View article: Analysis of Cation Composition in Dolomites on the Intact Particles Sampled from Asteroid Ryugu
Analysis of Cation Composition in Dolomites on the Intact Particles Sampled from Asteroid Ryugu Open
Characterization of the elemental distribution of samples with rough surfaces has been strongly desired for the analysis of various natural and artificial materials. Particularly for pristine and rare analytes with micrometer sizes embedde…
View article: Neodymium‐142 deficits and samarium neutron stratigraphy of C‐type asteroid (162173) Ryugu
Neodymium‐142 deficits and samarium neutron stratigraphy of C‐type asteroid (162173) Ryugu Open
We report Nd and Sm isotopic compositions of four samples of Ryugu returned by the Hayabusa2 mission, including “A” (first touchdown) and “C” (second touchdown) samples, and several carbonaceous chondrites to evaluate potential genetic rel…
View article: Nucleosynthetic s-Process Depletion in Mo from Ryugu samples returned by Hayabusa2
Nucleosynthetic s-Process Depletion in Mo from Ryugu samples returned by Hayabusa2 Open
Initial analyses of samples collected from two locations on the asteroid Ryugu indicated that the mineralogical, chemical, and isotopic characteristics of the Ryugu samples show similarities to carbonaceous chondrites, particularly the Ivu…
View article: The Magnesium Isotope Composition of Samples Returned from Asteroid Ryugu
The Magnesium Isotope Composition of Samples Returned from Asteroid Ryugu Open
The nucleosynthetic isotope composition of planetary materials provides a record of the heterogeneous distribution of stardust within the early solar system. In 2020 December, the Japan Aerospace Exploration Agency Hayabusa2 spacecraft ret…
View article: Pervasive aqueous alteration in the early Solar System revealed by potassium isotopic variations in Ryugu samples and carbonaceous chondrites
Pervasive aqueous alteration in the early Solar System revealed by potassium isotopic variations in Ryugu samples and carbonaceous chondrites Open
View article: Water circulation in Ryugu asteroid affected the distribution of nucleosynthetic isotope anomalies in returned sample
Water circulation in Ryugu asteroid affected the distribution of nucleosynthetic isotope anomalies in returned sample Open
Studies of material returned from Cb asteroid Ryugu have revealed considerable mineralogical and chemical heterogeneity, stemming primarily from brecciation and aqueous alteration. Isotopic anomalies could have also been affected by delive…
View article: The Oxygen Isotopic Composition of Samples Returned from Asteroid Ryugu with Implications for the Nature of the Parent Planetesimal
The Oxygen Isotopic Composition of Samples Returned from Asteroid Ryugu with Implications for the Nature of the Parent Planetesimal Open
We present oxygen isotopic analyses of fragments of the near-Earth C b -type asteroid Ryugu returned by the Hayabusa2 spacecraft that reinforce the close correspondence between Ryugu and CI chondrites. Small differences between Ryugu sampl…
View article: Abundant presolar grains and primordial organics preserved in carbon-rich exogenous clasts in asteroid Ryugu
Abundant presolar grains and primordial organics preserved in carbon-rich exogenous clasts in asteroid Ryugu Open
Preliminary analyses of asteroid Ryugu samples show kinship to aqueously altered CI (Ivuna-type) chondrites, suggesting similar origins. We report identification of C-rich, particularly primitive clasts in Ryugu samples that contain preser…
View article: Carbonate record of temporal change in oxygen fugacity and gaseous species in asteroid Ryugu
Carbonate record of temporal change in oxygen fugacity and gaseous species in asteroid Ryugu Open
View article: Hydrogen Isotopic Composition of Hydrous Minerals in Asteroid Ryugu
Hydrogen Isotopic Composition of Hydrous Minerals in Asteroid Ryugu Open
Rock fragments of the Cb-type asteroid Ryugu returned to Earth by the JAXA Hayabusa2 mission share mineralogical, chemical, and isotopic properties with the Ivuna-type (CI) carbonaceous chondrites. Similar to CI chondrites, these fragments…
View article: Author Correction: Contribution of Ryugu-like material to Earth’s volatile inventory by Cu and Zn isotopic analysis
Author Correction: Contribution of Ryugu-like material to Earth’s volatile inventory by Cu and Zn isotopic analysis Open
View article: Oxygen isotopes of anhydrous primary minerals show kinship between asteroid Ryugu and comet 81P/Wild2
Oxygen isotopes of anhydrous primary minerals show kinship between asteroid Ryugu and comet 81P/Wild2 Open
The extraterrestrial materials returned from asteroid (162173) Ryugu consist predominantly of low-temperature aqueously formed secondary minerals and are chemically and mineralogically similar to CI (Ivuna-type) carbonaceous chondrites. He…
View article: Contribution of Ryugu-like material to Earth’s volatile inventory by Cu and Zn isotopic analysis
Contribution of Ryugu-like material to Earth’s volatile inventory by Cu and Zn isotopic analysis Open
View article: Ryugu's nucleosynthetic heritage from the outskirts of the Solar System
Ryugu's nucleosynthetic heritage from the outskirts of the Solar System Open
Little is known about the origin of the spectral diversity of asteroids and what it says about conditions in the protoplanetary disk. Here, we show that samples returned from Cb-type asteroid Ryugu have Fe isotopic anomalies indistinguisha…
View article: Ryugu’s nucleosynthetic heritage from the outskirts of the Solar System
Ryugu’s nucleosynthetic heritage from the outskirts of the Solar System Open
Little is known about the origin of the spectral diversity of asteroids and what it says about conditions in the protoplanetary disk. Here, we show that samples returned from Cb-type asteroid Ryugu have Fe isotopic anomalies indistinguisha…
View article: The Solar System calcium isotopic composition inferred from Ryugu samples
The Solar System calcium isotopic composition inferred from Ryugu samples Open
CO CV CM CI Ryugu A Ryugu C 0.0 0.5 1.0 1.5 44/40CaSRM915a (age corrected) The Hayabusa2 spacecraft has returned samples from the Cb-type asteroid (162173) Ryugu to Earth. Previous petrological and chemical analyses support a close link be…
View article: Presolar Stardust in Asteroid Ryugu
Presolar Stardust in Asteroid Ryugu Open
We have conducted a NanoSIMS-based search for presolar material in samples recently returned from C-type asteroid Ryugu as part of JAXA's Hayabusa2 mission. We report the detection of all major presolar grain types with O- and C-anomalous …
View article: Samples returned from the asteroid Ryugu are similar to Ivuna-type carbonaceous meteorites
Samples returned from the asteroid Ryugu are similar to Ivuna-type carbonaceous meteorites Open
Carbonaceous meteorites are thought to be fragments of C-type (carbonaceous) asteroids. Samples of the C-type asteroid (162173) Ryugu were retrieved by the Hayabusa2 spacecraft. We measured the mineralogy and bulk chemical and isotopic com…