Prof. Shogo Tachibana of UTOPS gave a lecture at the Winter School “Small bodies of the Solar System and their link with extraterrestrial samples” held in Les Houches, France from February 4 (Sun.) to February 9 (Fri.), 2024.
For details, please refer to the following URL.
https://leshouches2024.sciencesconf.org/
Translated with www.DeepL.com/Translator (free version)
Joint Press Release
Masahiro Hoshino (Professor, Department of Earth and Planetary Sciences )
Takanobu Amano, Associate Professor, Department of Earth and Planetary Science
A research group led by Masanori Iwamoto, Project Assistant Professor at the Institute for Fundamental Physics, Kyoto University, Yosuke Matsumoto, Associate Professor at the International Advanced Research Institute, Chiba University, Takanobu Amano, Associate Professor at the Graduate School of Science, University of Tokyo, Masahiro Hoshino, Professor at the Graduate School of Science and Engineering, Kyushu University, and Shuichi Matsukiyo, Professor at the Interdisciplinary Graduate School of Science and Engineering, Kyushu University, has successfully reproduced high-speed radio bursts using the supercomputer “Fugaku”.
A fast radio burst is the largest radio explosion in the universe, which suddenly shines in radio waves for a very short time. They are believed to originate from shock waves formed around neutron stars with extremely strong magnetic fields called magnetars, but until now there has been no theoretical support for this belief. The results of this very large-scale simulation of the shock wave by Fugaku have demonstrated for the first time that the radio waves in the simulation are consistent with previous observations and correctly reproduce fast radio bursts.
Since the radio signals of fast radio bursts contain information about the universe they pass through, it is thought that they can be used as a tool to explore the evolution and structure of the universe. To this end, it is important to understand where and how fast radio bursts are generated, and this research is expected to make great strides in this direction and to have a ripple effect on other fields such as cosmology.
The results of this research were published online in the U.S. international journal Physical Review Letters on January 16, 2024.
For more information, please refer to the following
Graduate School of Science web: https://www.s.u-tokyo.ac.jp/ja/press/10211/
Publication URL: https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.132.035201
On Tuesday, January 23, 2024, Professor Shogo Tachibana of UTOPS gave a talk on Ryugu and Hayabusa2 to fifth graders at Nakamura Elementary School in Nerima Ward, Tokyo.
From the first to the fourth period, we went around to each class and interacted with energetic children.
Please refer to the following URLs 「宇宙のお話１」「宇宙のお話２」 for the scenes of the day.
Joint Press Release
Shogo Tachibana (Professor, Department of Earth and Planetary Science, ISAS)
Since the surface of an asteroid is not covered by an atmosphere, solar winds and cosmic dusts fall on the asteroid and change the chemical composition and other characteristics of materials on the asteroid’s top surface. A research team led by Assistant Professor Megumi Matsumoto and Professor Tomoki Nakamura of the Department of Earth Sciences, Graduate School of Science, Tohoku University, in collaboration with Ritsumeikan University, Kyoto University, the University of Tokyo, and others, observed the surface of rock particles brought back from the asteroid Ryugu by the Hayabusa2 probe using a scanning electron microscope, and found that the surface of the asteroid is covered with molten materials of 5 to 20 micrometers in size, formed when small cosmic dust particles hit the asteroid. The team discovered several melts of 5 to 20 micrometers in size, which were formed by the impact of small cosmic dust particles on the asteroid’s surface. 3D CT observation and chemical composition analysis of the melts revealed that they were formed by the melting and mixing of dust from the impacting comet and Ryugu’s surface material at high temperatures.
Comets form in the distant part of the solar system and are known to contain a large amount of organic matter that could be the material for life. The formation of molten material from cometary dust impacts likely occurred in the orbit of the present-day asteroid Ryugu about 5 million years ago, suggesting that Ryugu was supplied with cometary dust containing organic matter from distant parts of the solar system until very recently.
The results of this study were published on January 19, 2024 in Science Advances, a journal published by the American Association for the Advancement of Science (AAAS).
For more information, please refer to the following
Graduate School of Science web: https://www.s.u-tokyo.ac.jp/ja/press/10185/
Publication URL: https://www.science.org/doi/10.1126/sciadv.adi7203
On January 20 (Sat.) and 21 (Sun.), 2024, we held an astronomy training for students from Suwa Seiryo High School, Suwa Futaba High School, Matsumoto Misuzugaoka High School in Nagano Prefecture, and Ena High School in Gifu Prefecture. The students estimated the distance to galaxies from photographs of galaxies and used the recession speeds of these galaxies to determine the age of the universe.
Joint Press Release
Shogo Tachibana (Professor, Department of Earth and Planetary Science, ISAS)
Reflection spectra of asteroid recovered samples and meteorites provide clues to identify the constituent materials of asteroids from observationally obtained reflection spectra of asteroids.
A research group led by graduate student Kana Amano (currently a visiting researcher) and Professor Tomoki Nakamura of the Department of Earth Sciences, Graduate School of Science, Tohoku University, researcher Moe Matsuoka of the National Institute of Advanced Industrial Science and Technology (AIST), and Professor Shogo Tachibana of the Department of Earth and Planetary Science, Institute of Space and Planetary Science, Graduate School of Science, the University of Tokyo, and their colleagues have been studying asteroid samples recovered by the asteroid probe Hayabusa2 from asteroid Ryugu sample recovered from the asteroid Ryugu by the asteroid explorer Hayabusa2, and measured the reflection spectrum of the sample by devising a way to prevent it from reacting with the Earth’s atmosphere. By comparing Ryugu samples, meteorites from the same type of asteroid as Ryugu, and experimentally heated meteorites, they showed that the reaction of the meteorites with water and oxygen in the Earth’s atmosphere changed their reflection spectra to be brighter than they were in space. Based on this achievement, it is expected that the accuracy of identifying the constituent materials of asteroids by observation will be improved by considering how the reflection spectra of meteorites can change due to their alteration on the ground.
This result was published in Science Advances, a journal published by the American Association for the Advancement of Science (AAAS), on December 7, 2023.
For more information, please refer to the following
Graduate School of Science web: https://www.s.u-tokyo.ac.jp/ja/press/10144/
Publication URL: https://www.science.org/doi/10.1126/sciadv.adi3789
Joint Press Release
Aki Takigawa (Associate Professor, Department of Earth and Planetary Science)
Shogo Tachibana (Professor, Department of Earth and Planetary Science, ISAS)
Icy bodies and comets born far from the sun contain large amounts of nitrogen compounds such as ammonium salts. Such nitrogen-containing solids are thought to be very important as material for life, but no evidence of their transport to the Earth’s orbital region has been found. In this study, we examined sand from Ryugu, an asteroid orbiting near Earth, using an electron microscope and discovered that the very surface of the sand is covered with nitrided iron (iron nitride: Fe4N). Iron nitride is found on the surface of a mineral composed of iron and oxygen atoms called magnetite. We hypothesized that the iron nitride was formed by a chemical reaction on the surface of the magnetite when a small meteorite containing a large amount of ammonia compounds from an icy body hit Ryugu. On the surface of the asteroid, oxygen is lost from the magnetite surface due to exposure to ionic winds (solar wind) from the sun, and metallic iron, which easily reacts with ammonia, forms on the very surface. This is assumed to have promoted the synthesis of iron nitride derived from ammonia on the surface of the magnetite. This micrometeorite may have come from an icy body in the distant solar system, and it is possible that a larger amount of nitrogen compounds than previously realized were transported to the solar system near Earth to provide the material for life.
This work was conducted by a group led by Dr. Toru Matsumoto, a specific assistant professor at the Hakubi Center, Kyoto University; Dr. Takaaki Noguchi, a professor at the Graduate School of Science; Dr. Ryo Miyake, an associate professor; Dr. Yohei Igami, an assistant professor; Dr. Mitsutaka Haruta, an associate professor at the Institute for Chemical Research; and international collaborators, and published online in the British international journal Nature Astronomy on November 30, 2023, in the It was published online in the British international journal Nature Astronomy on November 30, 2023.
Professor Shogo Tachibana and Associate Professor Aki Takigawa of the Department of Earth and Planetary Sciences participated in the research results.
For more information, please refer to the following
Graduate School of Science web: https://www.s.u-tokyo.ac.jp/ja/press/10130/
Publication URL: https://www.nature.com/articles/s41550-023-02137-z
Joint Press Release
Takeshi Iizuka (Associate Professor, Department of Earth and Planetary Science)
Shogo Tachibana (Professor, Department of Earth and Planetary Science, ISAS)
A research group led by Professor Tetsuya Yokoyama of the Department of Earth and Planetary Science, Faculty of Science, Tokyo Institute of Technology, Associate Professor Tsuyoshi Iizuka and Professor Shogo Tachibana of the Graduate School of Science, University of Tokyo, and Professor Hisayoshi Yurimoto of the Graduate School of Science, Hokkaido University has measured the isotopic composition of the Cb-type asteroid Ryugu, and found that intense water metamorphism and water circulation on Ryugu caused local heterogeneity in chromium isotopic composition, They found that local inhomogeneities in chromium isotopic compositions were caused by the intense water metamorphism and water circulation that occurred on Ryugu.
Initial analysis of Ryugu samples revealed that the chemical and mineral compositions of the Cb-type asteroid Ryugu are similar to those of Ivuna-type carbonaceous meteorites, but there is a slight discrepancy between Ryugu and Ivuna-type carbonaceous meteorites in terms of chromium nucleosynthesis origin isotopic anomalies, the cause of which has been awaited to be clarified. The research group has been waiting for the cause of the anomaly to be clarified.
The research group measured nucleosynthetic origin isotope anomalies of chromium (54Cr) and titanium (50Ti) in a total of five Ryugu samples. The results showed that the 54Cr isotopic anomaly varied significantly from higher to lower than the average value for Ivna-type meteorites. This variation is inversely correlated with that of chromium isotopes (53Cr) derived from radiolytic decay of manganese-53 (53Mn), a short-lived nuclide. The 54Cr isotopic anomaly in the combined Ryugu samples (7-24 mg) (about 90 mg) is consistent with the average value for Ivna-type carbonaceous meteorites. In the initial analysis of the Bennu samples brought back by OSIRIS-REx, it was found that it is desirable to analyze a certain amount of sample (>0.1 g) in order to avoid the influence of heterogeneity.
The results of this research were published online in Science Advances on November 9, 2023 Japan time.
For more information, please refer to the following
Graduate School of Science web: https://www.s.u-tokyo.ac.jp/ja/press/10087/
Publication URL: https://www.science.org/doi/10.1126/sciadv.adi7048
