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We're cheerful astronomers and university students exploring radio observational astrophysics on interstellar and circumstellar mediums.

We are studying "dark sides" of stellar evolution in radio wavelengths using a special observational technique so-called "interferometry".

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Team's introduction video (produced in 2020 April)

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Our team's keywords

1. Death and birth of stars

We are studying special periods of transition phases between the "main sequence" stage of stars and the stage when the material that will form next-generation stars is distributed into circumstellar spaces through circumstellar envelopes of evolved and dying stars. Because such phases of death and birth of stars are much shorter than the main sequence stage, it is difficult to study the objects in such situations of stars without excellent strategies to look for the target stars and "stellar objects" and comprehensive knowledge of physics, chemistry, and mathematics as tools for quantitative analysis and discussion.

2. Interstellar and circumstellar matters

The matters that would be released from evolved and dying stars and will be collected to form the next generation of stars are distributed in huge volumes of the Milky Way (Amanogawa) Galaxy and external galaxies. Large sky surveys are one of our challenging issues for elucidating the whole picture of the "re-cycling" of cosmic matter. In particular, it is crucial to explore its "hierarchical" structures from one astronomical unit (1 au=150 million-kilometers) to one kilo-parsec (kpc=200 million-au) for understanding how the gas and dust in the interstellar and circumstellar matters are distributed and collected on specific timescales.

3. Radio interferometry

High quality radio images of studied celestial objects can be nowadays synthesized using the "interferometry technique". Image synthesis in higher sensitivity needs a larger aperture area of a radio telescope or, alternatively, a larger number of small telescopes whose received radio signals are correlated or synchronized with each other. Higher angular resolution of images is yielded with a larger diameter of a telescope or longer "baselines" between small telescopes that shall observe the same target at the exactly same time. Continental and intercontinental interferometry is possible in "very long baseline interferometry" (VLBI) technique, in which the individual "stations" have accurate clocks (frequency standards) and a high-speed signal transmission and recording systems as well as a telescope (or telescopes) whose coordinates on Earth have been monitored accurately and regularly.

4. International collaborations

The large sky surveys and VLBI observations described above need international or global collaborations. They have been constructed through exchanges in fresh information, research ideas, observation opportunities, and direct visits over years and decades. The present information technologies enable us to intensively and effectively communicate with foreign colleagues towards establishments of research teams and organizations. Fluent communications in English language will provide our global views in not only astronomy and astrophysics but also a wider variety of friendship and human activities.


Our teams's used facilities

VLBI Exploration of Radio Astrometry


Four 20 m dish telescopes in Japan, that are specially equipped with the dual-beam receiving system, dedicated for high precision trigonometry of radio sources, and have been operated since 2002.

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45 m telescope of Nobeyama Radio Observatory

NRO 45 m telescope

Millimeter large telescope operated since 1982 to observe 20--116~GHz emission in high sensitivity.

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East Asian VLBI Network


New VLBI network that is composed of Japanese, Korean, and Chinese telescopes including VERA, Nobeyama, FAST, etc., and has been scientifically operated since 2018.

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Atacama Large Millimeter-submillimeter Array


Imaging millimeter and submillimeter emission in 10 milli-arcsecond resolution.

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Space VLBI


Russia-lead space VLBI program conducted with the spacecraft of 10 m telescope, operated during 2013--2019, and ground radio telescopes.

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Australian SKA Pathfinder


Australian Precursor of the Square Kilometre Array (SKA), equipped with phased-array feeds with a fiew-of-view of 30 square degrees.

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Square Kilometre Array


World's largest radio telescope array whose construction started in 2022.

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Our teams's projects

EAVN Synthesis of Stellar Maser Animations


Decadal, intensive monitoring observations of circumstellar SiO and H2O masers with EAVN since 2018.

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Finest Legacy Acquitisions of SiO and H2O Maser Ignitions by Nobeyama Generation


Intensive monitoring observations of silicon-monoxide and water masers associated with "water fountain" sources.

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Nearby Evolved Star Survey in Nobeyama


Comprehensive radio mapping of the circumstellar envelopes around nearby long period variable stars using the Nobeyama 45 m telescope during 2017--2023.

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Hybrid Integration Project in Nobeyama, Triple-band Oriented


Upgrading the optics with a triple-band simultaneous observing system and the VLBI backend system in the Nobeyama 45 m telescope.

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Square Kilometer Array


Contributions to new constructions of the world's largest radio astronomy facility.

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