HISAKI Project Team
Profile Information
- Affiliation
- Graduate School of Science, Japan Aerospace Exploration Agency
- Degree
- 修士（学術）(東京大学)博士（理学）(東京大学)
- ORCID ID
https://orcid.org/0000-0003-2273-0103- J-GLOBAL ID
- 201601015297652541
- researchmap Member ID
- 7000017299
Research Areas
2Research History
7-
Aug, 2020 - Present
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Apr, 2016 - Jul, 2020
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Aug, 2013 - Mar, 2016
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Apr, 2009 - Jul, 2013
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Oct, 2003 - Mar, 2009
Education
4-
Apr, 1996 - Mar, 1998
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Apr, 1993 - Mar, 1996
Awards
2Papers
148-
Publications of the Astronomical Society of Japan, Apr 10, 2024Abstract The Japan Astrometry Satellite Mission for INfrared Exploration (JASMINE) is a planned M-class science space mission by the Institute of Space and Astronautical Science, the Japan Aerospace Exploration Agency. JASMINE has two main science goals. One is Galactic archaeology with a Galactic Center survey, which aims to reveal the Milky Way’s central core structure and formation history from Gaia-level (∼25 ${\mu} $as) astrometry in the near-infrared (NIR) Hw band (1.0–1.6 ${\mu} $m). The other is an exoplanet survey, which aims to discover transiting Earth-like exoplanets in the habitable zone from NIR time-series photometry of M dwarfs when the Galactic Center is not accessible. We introduce the mission, review many science objectives, and present the instrument concept. JASMINE will be the first dedicated NIR astrometry space mission and provide precise astrometric information on the stars in the Galactic Center, taking advantage of the significantly lower extinction in the NIR. The precise astrometry is obtained by taking many short-exposure images. Hence, the JASMINE Galactic Center survey data will be valuable for studies of exoplanet transits, asteroseismology, variable stars, and microlensing studies, including discovery of (intermediate-mass) black holes. We highlight a swath of such potential science, and also describe synergies with other missions.
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Astronomy & Astrophysics, Aug 23, 2023
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Monthly Notices of the Royal Astronomical Society, Apr 7, 2023Abstract We have conducted numerical simulations to reproduce the observed optical energy profile of the 15 October 2021 (UT) impact flash on Jupiter, which was the largest and the most well-observed flash event detected by ground-based movie observations. The observed long-duration (∼5.5 s) optical emission can be reproduced by an impact of an object with an exceptionally small angle of entry relative to the horizontal. The apparent lack of the impact debris feature despite the large impact object was possibly due to the shallower angle of entry (≤12○), which resulted in the lower ablation per unit volume at altitudes higher than 50 km, and the volume densities of the ablated materials were too low to allow the debris particulates to coagulate. The absence of temporal methane absorption change in the observed flash spectrum is consistent with the best-fit results. The model better fits the observed optical energy profile for weaker material (cometary and stony) cases than for metallic ones. Based on the simulation results, prospects for future observations of impact flashes are discussed.
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Proceedings of SPIE, Ground-based and Airborne Instrumentation for Astronomy IX, 12184, Aug 29, 2022MIMIZUKU is the first-generation mid-infrared instrument for the TAO 6.5-m telescope. It has three internal optical channels to cover a wide wavelength range from 2 to 38 mu m. Of the three channels, the NIR channel is responsible for observations in the shortest wavelength range, shorter than 5.3 mu m. The performance of the NIR channel is evaluated in the laboratory. Through the tests, we confirm the followings: 1) the detector (HAWAII-1RG with 5.3-mu m cutoff) likely achieves similar to 80% quantum efficiency; 2) imaging performance is sufficient to achieve seeing-limit spatial resolution; 3) system efficiencies in imaging modes are 2.4-31%; and 4) the system efficiencies in spectroscopic modes is 5-18%. These results suggest that the optical performance of the NIR channel is achieved as expected from characteristics of the optical components. However, calculations of the background levels and on-sky sensitivity based on these results suggest that neutral density (ND) filters are needed to avoid saturation in L'- and M'-band observations and that the ND filters and the entrance window, made of chemical-vapor-deposition (CVD) diamond, significantly degrade the sensitivity in these bands. This means that the use of different window materials and improvements of the detector readout speed are required to achieve both near-infrared and long-wavelength mid-infrared (>30 mu m) observations.
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PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN, 74(4) 877-903, Aug, 2022We report the results of video observations of tiny (diameter less than 100 m) near-Earth objects (NEOs) with Tomo-e Gozen on the Kiso 105 cm Schmidt telescope. The rotational period of a tiny asteroid reflects its dynamical history and physical properties since smaller objects are sensitive to the Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) effect. We carried out video observations of 60 tiny NEOs at 2 fps from 2018 to 2021 and successfully derived the rotational periods and axial ratios of 32 NEOs including 13 fast rotators with rotational periods less than 60 s. The fastest rotator found during our survey is 2020 HS7 with a rotational period of 2.99 s. We statistically confirmed that there is a certain number of tiny fast rotators in the NEO population, which have been missed with all previous surveys. We have discovered that the distribution of the tiny NEOs in a diameter and rotational period (D-P) diagram is truncated around a period of 10 s. The truncation with a flat-top shape is not explained well by either a realistic tensile strength of NEOs or the suppression of YORP by meteoroid impacts. We propose that the dependence of the tangential YORP effect on the rotational period potentially explains the observed pattern in the D-P diagram.
Misc.
133-
宇宙科学技術連合講演会講演集(CD-ROM), 66th, 2022
Presentations
28-
Asteroid Science in the Age of Hayabusa2 and OSIRIS-REx, Nov, 2019
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EPSC-DPS Joint Meeting 2019, Sep, 2019
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Mid-infrared Astronomy --- Past 20 years & Future 20 years, Aug, 2019
Teaching Experience
1-
惑星学特別講義Ⅱ (神戸大学)
Professional Memberships
5Research Projects
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科学研究費助成事業 基盤研究(A), 日本学術振興会, Apr, 2020 - Mar, 2024
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科学研究費助成事業 基盤研究(A), 日本学術振興会, Apr, 2019 - Mar, 2024
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Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C), Japan Society for the Promotion of Science, Apr, 2020 - Mar, 2023
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Grants-in-Aid for Scientific Research, Japan Society for the Promotion of Science, Apr, 2017 - Mar, 2020
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Grants-in-Aid for Scientific Research, Japan Society for the Promotion of Science, Apr, 2015 - Mar, 2020
