Institute of Astronomy, Univ. of Tokyo

News

AUGUST 7, 2025 Press Release: The galaxy was grainier than expected just after birth; A research team including members from the University of Toronto and the University of Tokyo has revealed that a faint, young galaxy, which existed about 900 million years after the Big Bang, exhibits a fragmented structure resembling a "bunch of grapes," composed of at least 15 compact star clusters. Despite this fragmented appearance, the galaxy as a whole displays smooth rotational motion of its gas. This structure was unexpected, as it deviates significantly from previous observations and numerical simulation predictions. The galaxy studied is representative of typical galaxies from that era, suggesting that similar structures may be hidden in many others. These findings could lead to a significant revision of our understanding of galaxy formation in the early universe.
July 1, 2025 Press Release: Galaxies Grow Stars with Gas from Outside; A research group led by Maki Nagata, a graduate student in the Department of Astronomy at the Graduate School of Science, The University of Tokyo, has discovered ten molecular clouds in the nearby barred spiral galaxy M83 that are moving at velocities significantly different from the galaxy’s disk rotation. This study systematically investigates high-velocity clouds (HVCs) composed of molecular gas, which had not previously been observed flowing into the galactic disk in nearby galaxies. Detecting the inflow of such high-density gas from outside the galaxy is expected to provide key insights into how galaxies sustain star formation over long timescales.
May 22, 2025 Press Release: A fierce storm in a giant barred spiral galaxy 11 billion years ago; ALMA has obtained detailed images of the gas distribution and motion in the barred spiral structure of a monster galaxy. The results reveal that this galaxy, which existed in the early universe, looks very similar to barred spiral galaxies in the present-day universe, but the gas within its barred structure is blowing violently and causing intense star formation. This is an important research result that adds new knowledge to the history of galaxy growth and evolution.
May 13, 2025 News: Japan–Chile Summit Discusses Cooperation in Space and Astronomy; On May 11, 2025, Prime Minister Shigeru Ishiba held a summit meeting lasting approximately 70 minutes with President Gabriel Boric Font of the Republic of Chile, who was visiting Japan as a guest for Expo 2025 Osaka, Kansai. The two leaders shared a sense of cultural closeness, particularly through their mutual interest in Japanese literature. Notably, they expressed hopes for further collaboration in the fields of space and astronomy, citing the commemorative ceremony marking the completion of the University of Tokyo Atacama Observatory (TAO) telescope site. Click here for the TAO webpage regarding this news.

Photo: quoted from the webpage of Ministry of Foreign Affairs of Japan
Mar 24, 2025 News: Associate Professor Shigeyuki Sako has been awarded the Shoichiro Yoshida Memorial Nikon Astronomy Achievement Award; Associate Professor Shigeyuki Sako of the Institute of Astronomy has been awarded the 2024 Shoichiro Yoshida Memorial Nikon Astronomy Achievement Award. This prestigious award, presented annually by the Japan Astronomical Foundation, honors researchers who have made remarkable contributions to the advancement of astronomical observation methods, particularly those involved in the development of cutting-edge astronomical instruments. The system, named "Tomo-e Gozen" — after the legendary warrior associated with Kiso — continues to operate at Kiso Observatory, capturing an impressive average of 8 terabytes of data per night. This unprecedented data stream has significantly contributed to the advancement of time-domain astronomy in Japan.
Feb 12, 2025 News: Big Data Science in the Beautiful Night Sky of Kiso; The ceremony celebrating the 50th anniversary of Kiso Observatory was held on December 8, 2024, at the Cultural Hall of Kiso Cultural Park in Kiso County, Nagano Prefecture, with many distinguished guests in attendance. Kiso Observatory was established in 1974 and has since fostered many astronomers and made significant astronomical contributions. As the only domestic observatory operated by the University of Tokyo, it has been dedicated to research and education, and in recent years has also focused on social engagement and regional collaboration.
SEP 30, 2024 News: Succeeded in photography of Comet Tsuchinshan-Atlas at TAO summit facility!; The University of Tokyo Atacama Observatory (TAO) will attempt to photograph Comet Tsuchinshan-Atlas in the early morning hours of September 30 to October 4, 2024 in Chilean time.If we are successful in photography of Comet Tsuchinshan-Atlas, it will be posted on this website.

On the first day of photography, September 30, 2024 at 04:48-06:30 (CST), we succeeded in taking a still photograph and a time-lapse video of the comet! The photo shows Comet Tsuchinshan-Atlas at 6:09 a.m. on September 30 (CST).

※The following credit is required for use of the photograph. “Photographed by TAO Project, The University of Tokyo/Akio Nakanishi”
May 2, 2024 News: The University of Tokyo Atacama Observatory (TAO) Telescope Site Completion Ceremony Holds; The University of Tokyo Atacama Observatory (TAO) Project is to construct the 6.5m optical-infrared telescope at summit of Cerro Chajnantor, an altitude of 5,640 m (18,500 ft) in the Atacama Desert of northern Chile. As the construction work at the telescope site progresses, and the summit facilities including the enclosure have been completed, a commemorative ceremony was held on April 30, 2024 in Santiago, the capital of the Republic of Chile, to celebrate the completion of the TAO telescope site and to pray for safety and success in the operation of the TAO telescope. Link to Graduate School of Science.
January 30, 2023 Press Release: First in the world! AI-generated map of the molecular gas cloud distribution in the Milky Way galaxy; A research group led by Shinji Fujita, a Research Fellow at the Graduate School of Science, University of Tokyo, has identified approximately 140,000 interstellar molecular clouds from detailed observations of the Milky Way galaxy using the National Astronomical Observatory of Japan's Nobeyama 45m radio telescope. Using artificial intelligence, they estimated the distance of each of the clouds, calculated the size and mass of interstellar molecular clouds in the Milky Way galaxy, and successfully drew the most detailed distribution of interstellar molecular clouds in the Milky Way galaxy's disk. This research is expected to have an impact on various astronomical studies, such as the calculation of the frequency of "collisions between interstellar molecular clouds," which are considered important events in creating large stars and star clusters.
November 28, 2022 Press Release: Toward unveiling the cosmic mystery of Fast Radio Bursts; Since 2007, astronomers have been observing fleeting bursts of bright, energetic radio waves lasting milliseconds to microseconds in space. They call them Fast Radio Bursts (FRBs). But what produces these high-energy bursts baffles astronomers. To understand the origins of FRBs, a team of scientists led by Bunyo Hatsukade, an Assistant Professor at the University of Tokyo, probed the molecular gas of their host galaxies.
August 9, 2022 Press Release: Very Fast Optical Flashes from Red Dwarfs Revealed by Video Observations; Video observations by Tomo-e Gozen have discovered 22 very fast and powerful optical flares from red dwarfs, which have been difficult to be detected. Such very fast and powerful flares are likely to be produced by instantaneous energy release of strong magnetic fields, potentially giving an impact on planetary habitability around red dwarfs.
July 13, 2022 Press Release: Fast rotations of near-Earth asteroids revealed by video observations; Tomo-e Gozen carried out video observations of 60 tiny (diameter less than 100 m) near-Earth asteroids (NEAs) and successfully derived rotational periods and axial ratios of 32 NEAs. The distribution of the tiny NEAs in a diameter and rotational period (D-P) diagram is truncated around a period of 10 s. The dependence of the tangential YORP effect on the rotational period potentially explains the observed pattern in the D-P diagram.
May 18, 2022 Press Release: Detection of Highly Correlated Optical and X-ray Time Variations in SS Cygni; Tomo-e Gozen and the X-ray telescope NICER on the International Space Station carried out simultaneous high-speed observations of the dwarf nova SS Cyg. Highly correlated optical and X-ray variations and optical lags ranging from 0.3 to 3.1 s were successfully detected.

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