On August 1 (Tue.) and 2 (Wed.), 2023, we held an astronomy lab for students from Matsumoto Fukashi High School in Nagano Prefecture and Kariya High School in Aichi Prefecture. The students estimated the distance to galaxies from photographs of galaxies and used the recession velocity of those galaxies to determine the age of the Universe.
Joint Press Release
Shogo Tachibana (Professor, Department of Earth and Planetary Science)
Takeshi Iizuka (Associate Professor, Department of Earth and Planetary Science)
A research team led by Associate Professor Wataru Fujiya of the Graduate School of Science and Engineering, Ibaraki University, Associate Professor Noriyuki Kawazaki and Professor Hisayoshi Yurimoto of the Graduate School of Science, Hokkaido University, Professor Tetsuya Yokoyama of the Department of Earth and Planetary Science, Graduate School of Science, Tokyo Institute of Technology, and Professor Shogo Tachibana of the Graduate School of Science, University of Tokyo, has analyzed samples from the asteroid Ryugu samples recovered by the Hayabusa2 spacecraft, and have elucidated the evolution of oxygen concentrations and gas molecular species present on Ryugu.
In this study, we examined the abundance ratios of carbon and oxygen isotopes in the carbonate minerals (calcite and dolomite) in Ryugu’s samples. The results showed that the isotope ratios of both carbon and oxygen in calcite varied greatly among the different particles, while those in mafic calcite varied little. These results suggest that calcite formed early in the alteration process at Ryugu, when temperatures and oxygen concentrations were rising and the fraction of gas species was changing, while the calcite was formed at higher temperatures and with a relatively high fraction of carbon dioxide in the gas, while the system was in equilibrium.
Such isotopic compositions of carbonate minerals have not been reported in previous meteorite studies. This suggests that Ryugu and its meteorite parent bodies were composed of different materials and evolved in unique environments.
The results were published online in Nature Geoscience on Wednesday, July 10, 2023.
For more information, please see
Graduate School of Science web: https://www.s.u-tokyo.ac.jp/ja/info/8544/
Publication URL: https://www.nature.com/articles/s41561-023-01226-y
Joint Press Release
Motohide Tamura, Professor, Department of Astronomy)
More than 5,000 exoplanets have been discovered so far, but most of them were discovered through indirect observations, and only about 20 of them were directly imaged by direct imaging, which captures light from exoplanets directly. This is because direct imaging has so far been used to search for exoplanets blindly by observing a large number of objects, because it is not possible to narrow down the target of observation.
However, the advent of satellites that can precisely measure the positions of fixed stars on the celestial sphere has overcome this situation. Using precise astrometry data from the Gaia satellite launched by the European Space Agency and its predecessor, the Hipparcos satellite, it became possible to obtain indirect evidence for the existence of a planet from the wobble (accelerated motion) of a star and directly image promising objects using large telescopes and super-compensation optics. This is the first time that a direct imaging method has become possible using large telescopes and super-compensation optics.
An international research team led by researchers from the University of Tokyo’s Graduate School of Science has now successfully discovered a new exoplanet, HIP 99770 b, by direct imaging using this technique and the Subaru Telescope’s supercompensating optics instrument (see Figures 1 and 2). This exoplanet orbits the star HIP 99770, which is 130 light years away in the constellation Cygnus and is visible to the naked eye with an apparent brightness of 4th magnitude, 17 times the distance between the Sun and Earth. By taking into account the stellar wobble data, the mass of the exoplanet was estimated to be 15 ± 1 times the mass of Jupiter, which is a much more precise estimate for an exoplanet found by direct imaging.
Planets discovered with this technique are ideal for demonstrating the high-contrast observations that will be made with the ground-based Very Large Telescope in the future. It is also a promising technique for imaging Earth’s twin in the future.
The results of this research were published as Currie et al. “Direct Imaging and Astrometric Detection of a Gas Giant Planet Orbiting an Accelerating Star” in the US The results of this research were published in the U.S. scientific journal Science on April 13, 2023.
Professor Motohide Tamura of the Department of Astronomy participated in this research.
For more information, please visit the website of NAOJ Hawaii Observatory and NAOJ. The results are also available at the Center for Astrobiology.
Following enormous collisions, such as asteroid impacts, some amount of material from an impacted world may be ejected into space. This material can travel vast distances and for extremely long periods of time. In theory this material could contain direct or indirect signs of life from the host world, such as fossils of microorganisms. And this material could be detectable by humans in the near future, or even now.
When you hear the words vacuum and dust in a sentence, you may groan at the thought of having to do the housework. But in astronomy, these words have different connotations. Vacuum of course refers to the void of space. Dust, however, means diffuse solid material floating through space. It can be an annoyance to some astronomers as it may hinder their views of some distant object. Or dust could be a useful tool to help other astronomers learn about something distant without having to leave the safety of our own planet. Professor Tomonori Totani from the University of Tokyo’s Department of Astronomy has an idea for space dust that might sound like science fiction but actually warrants serious consideration.
“I propose we study well-preserved grains ejected from other worlds for potential signs of life,” said Totani. “The search for life outside our solar system typically means a search for signs of communication, which would indicate intelligent life but precludes any pre-technological life. Or the search is for atmospheric signatures that might hint at life, but without direct confirmation there could always be an explanation that does not require life. However, if there are signs of life in dust grains, not only could we be certain, but we could also find out soon.”
The basic idea is that large asteroid strikes can eject ground material into space. There is a chance that recently deceased or even fossilized microorganisms could be contained in some rocky material in this ejecta. This material will vary in size greatly, with different-sized pieces behaving differently once in space. Some larger pieces might fall back down or enter permanent orbits around a local planet or star. And some much smaller pieces might be too small to contain any verifiable signs of life. But grains in the region of 1 micrometer (one-thousandth of a millimeter) could not only host a specimen of a single-celled organism, but they could also potentially escape their host solar system altogether, and under the right circumstances, maybe even venture to ours.
“My paper explores this idea using available data on the different aspects of this scenario,” said Totani. “The distances and times involved can be vast, and both reduce the chance any ejecta containing life signs from another world could even reach us. Add to that the number of phenomena in space that can destroy small objects due to heat or radiation, and the chances get even lower. Despite that, I calculate around 100,000 such grains could be landing on Earth every year. Given there are many unknowns involved, this estimate could be too high or too low, but the means to explore it already exist so it seems like a worthwhile pursuit.”
There may be such grains already on Earth, and in plentiful amounts, preserved in places such as the Antarctic ice, or under the seafloor. Space dust in these places could be retrieved relatively easily, but discerning extrasolar material from material originating in our own solar system is still a complex matter. If the search is extended to space itself, however, there are already missions that capture dust in the vacuum using ultralight materials called aerogels.
Tomonori Totani, “Solid grains ejected from terrestrial exoplanets as a probe of the abundance of life in the Milky Way,” International Journal of Astrobiology: March 22, 2023, doi:10.48550/arXiv.2210.07084.
Link (Publication)
Joint Press Release
Shogo Tachibana, Professor at the Institute of Space and Planetary Science (ISAS) / Specially Appointed Professor at the Institute of Space and Astronautical Science (JAXA)
An international research group led by Associate Professor Yasuhiro Oba of the Institute of Low Temperature Science, Hokkaido University, Senior Researcher Yoshinori Takano of the Japan Agency for Marine-Earth Science and Technology (JAMSTEC), and Professor Hiroshi Naraoka of the Graduate School of Science, Kyushu University, has successfully detected uracil, a nucleobase contained in all RNA of Earth life, in particles from the asteroid Ryugu brought back by the asteroid probe “Hayabusa2 They succeeded in detecting uracil, a nucleobase contained in the RNA of all life on Earth, in a particle from the asteroid Ryugu brought back by the Hayabusa2 spacecraft. In addition, vitamin B3 (niacin), an important coenzyme related to the metabolism of life, was also detected in the same sample.
In December 2020, the asteroid Ryugu sample was delivered to Earth by the asteroid probe Hayabusa2, making it the world’s first sample collected directly from a carbonaceous asteroid to be analyzed in a laboratory (published in Science on February 10, 2022). The Soluble Organic Molecules Analysis Team, one of the initial analysis subteams, has previously demonstrated the presence of various organic compounds, such as amino acids and carboxylic acids, in Ryugu samples (published in Science on February 24, 2023). In this study, we focused on nitrogen-containing cyclic organic compounds (nitrogen heterocyclic compounds) and verified their presence in Ryugu samples in detail.
Using an ultra-sensitive analytical method developed by the research team, they succeeded in detecting uracil, one of the nucleobases contained in the RNA of all Earth life, and vitamin B3 (niacin), one of the coenzymes essential for the metabolism of life, in a Ryugu sample of about 10 milligrams. These detections provide a real picture of the chemical evolution of organic molecules and strongly support the theory that components supplied by extraterrestrial materials such as carbonaceous meteorites (i.e., asteroid fragments) were the materials for the ultimate mystery in science: how the first life on the primitive Earth was created before the birth of life. The results of this research are expected to be published in 2023.
For more information, please refer to the following
Graduate School of Science press release: https://www.s.u-tokyo.ac.jp/ja/info/8330/
Publication URL: https://doi.org/10.1038/s41467-023-36904-3
Joint Press Release
Professor Shogo Tachibana, Professor Seiji Sugita, Associate Professor Tomokatsu Morota, Special Staff Shizuho Furuya
Soluble organic molecules contained in the Ryugu sample brought back by Hayabusa2 were analyzed mainly by solvent extraction. Ryugu is a dark primitive asteroid belonging to the C-type asteroids, which are the most common in the asteroid belt, and is rich in hydrous minerals such as carbonaceous chondrite meteorites. Primitive carbonaceous chondrites are known to contain a variety of soluble organic molecules, including amino acids, and may have supplied preliving organic molecules that led to the birth of life to the early Earth and other celestial bodies. In this study, organic molecules contained in Ryugu surface samples obtained from the first touchdown sampling were analyzed by research teams from Japan, the U.S., and Europe. As a result, various organic molecules such as amino acids, amines, carboxylic acids, aromatic hydrocarbons, and nitrogen-containing cyclic compounds were detected. These organic molecules could be released from Ryugu’s surface and transported to other celestial bodies, or they could be used as organic resources.
For more information, please see
JAXA press release: https://www.jaxa.jp/press/2023/02/20230224-1_j.html
Graduate School of Science press release: https://www.s.u-tokyo.ac.jp/ja/info/8304/
Publication URL: https://www.science.org/doi/10.1126/science.abn9033
Joint Press Release
Professor Shogo Tachibana, Assistant Professor Taiga Okumura, Professor Yoshio Takahashi, Professor Seiji Sugita, Associate Professor Tomokatsu Morota, Special Staff Shizuho Furuya
The Solid Organic Matter Analysis Team, led by Professor Hikaru Yabuta of the Graduate School of Advanced Science and Engineering, Hiroshima University, analyzed the chemical composition, isotopic composition, and morphology of solid organic matter in the asteroid Ryugu sample brought back to Earth by the asteroid probe “Hayabusa2”. The non-destructive analysis of the Asteroid Ryugu sample (37 microparticles ranging in size from 200 to 900 μm) using various microspectroscopic techniques revealed that the types and proportions of chemical bonds comprising the organic matter in the sample were similar to those of the most primitive Ivuna-type carbonaceous chondrite (CI Group) and primitive Mighei-type carbonaceous chondrite (CM Group). Electron microscopic examination of them revealed nanometer-sized spherical organic matter and thinly spread irregularly shaped organic matter adjacent to or mixed with layered silicates and carbonates. Their coexistence with secondary minerals produced in Ryugu’s parent body is evidence that these organic materials also originated from reactions with liquid water in the parent body. The absence of graphite-like ordered structures in the Ryugu samples means that the organic matter in the Ryugu samples analyzed was not heated to high temperatures in the parent body interior or by impact.
In addition, the isotopic composition of the Ryugu sample revealed regions of deuterium and nitrogen15 concentrations. Such isotopic compositions are not found in terrestrial organic matter and are known to occur only in low-temperature environments of a few tens of Kelvin (minus 200°C or lower). Thus, the Ryugu organics analyzed are indeed of extraterrestrial origin, and at least some of these organics were formed in cryogenic environments such as interstellar molecular clouds and the outer protoplanetary disk.
For more information, please see
JAXA press release: https://www.jaxa.jp/press/2023/02/20230224-2_j.html
Graduate School of Science press release: https://www.s.u-tokyo.ac.jp/ja/press/2023/8303/
Publication URL: https://www.science.org/doi/10.1126/science.abn9057
Notice of cancellation
The symposium will be postponed due to the spread of the new coronavirus infection.
When the situation calms down, we would like to plan a similar meeting again
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We will hold the new Integrated Research System:
Collaborative Research organization for Space and Technology
(CROiSSanT) commemorative symposium on Monday 9th March at Koshiba Hall,
School of Science Bldg.1, The University of Tokyo.
