Dept. of Space Astronomy and Astrophysics

高橋 葵

タカハシ アオイ  (Aoi Takahashi)

基本情報

所属
国立研究開発法人宇宙航空研究開発機構 宇宙科学研究所 助教
学位
博士(理学)(2019年3月 総合研究大学院大学)

研究者番号
70851848
ORCID ID
 https://orcid.org/0000-0003-3881-3202
J-GLOBAL ID
202401009211368481
researchmap会員ID
R000065754

委員歴

 1

主要な論文

 28
  • Masaki Hanzawa, Shuji Matsuura, Aoi Takahashi, Ranga-Ram Chary, Kei Sano, Kohji Takimoto, Yuto Tome
    PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN 76(3) 353-364 2024年3月21日  
    Measuring the absolute brightness of the zodiacal light (ZL), which is the sunlight scattered by interplanetary dust particles, is important not only for understanding the physical properties of the dust but also for constraining the extragalactic background light (EBL) by subtracting the ZL foreground. We describe the results of high-resolution spectroscopic observations of the night sky in the wavelength range of 300-900 nm with the double spectrograph on the Hale telescope to determine the absolute brightness of the ZL continuum spectra from the Fraunhofer absorption line intensities. The observed fields are part of the fields observed by the Spitzer Space Telescope for the EBL study. Assuming that the spectral shape of the zodiacal light is identical to the solar spectrum in a narrow region around the Fraunhofer lines, we decomposed the observed sky brightness into multiple emission components by amplitude parameter fitting with spectral templates of the airglow, ZL, diffuse Galactic light, integrated starlight, and other isotropic components including EBL. As a result, the ZL component with the Ca ii lambda lambda 393.3, 396.8 nm Fraunhofer lines around 400 nm is clearly separated from the others in all fields with uncertainties around 20%, mainly due to the template errors and the time variability of the airglow. The observed ZL brightness in most of the observed fields is consistent with the modeled ZL brightness calculated by combining the most conventional ZL model at 1250 nm based on the Diffuse Infrared Background Experiment and the observational ZL template spectrum based on the Hubble Space Telescope. However, the ecliptic plane observation is considerably fainter than the ZL model, and this discrepancy is discussed in terms of the optical properties of the interplanetary dust accreted in the ecliptic plane.
  • Aoi Takahashi, Takayuki Kotani, Masayuki Kuzuhara, Takeru Nakajima, Riku Urago, Kou Hosokawa, Shotaro Tada, Motohide Tamura, Jun Nishikawa, Akitoshi Ueda, Takuya Takarada, Teruyuki Hirano, Takuma Kokusho, Eiko Kozaki, Takahiro Nagayama, Takahiro Sumi, Daisuke Suzuki, Hibiki Yama, Tomoyasu Yamamuro
    GROUND-BASED AND AIRBORNE INSTRUMENTATION FOR ASTRONOMY X 13096 2024年  筆頭著者
    The South Africa Near-infrared Doppler instrument (SAND) is a time-stable high-dispersion spectrograph, covering the z- and Y-bands simultaneously (849 - 1085 nm) with the maximum spectral resolution of similar to 60,000. We aim to monitor the radial velocity of M-dwarfs with the precision of a few m/s level, which enables us to search for habitable exoplanets. Our another scientific motivation is the statistical investigation of young planets and stellar atmosphere to comprehensively understand the formation senario of stellar systems. We are planning to install the SAND to telescopes at the South African Astronomical Observatory (SAAO) in Sutherland, since the Southern sky covers plentiful stellar associations with young stars. The SAND is a fiber-fed spectrograph, and we can change telescope used to collect the star light by switching the fiber connection. It will be operated mainly with two telescopes: the Prime-focus Infrared Microlensing Experience telescope (PRIME) and the InfraRed Survey Facility (IRSF), which both are managed by universities in Japan. This strategy of using multiple telescopes gives us opportunities of frequent and long-term observations, which provides well phase coverage in radial velocity monitoring and results in non-bias search for exoplanets. Most of the components used in the spectrograph and the fiber injection module have been fabricated. We will present the detailed status and recent progress: designing the fiber injection module and the thermal control system, examination of fiber characteristics, and estimating our target candidates.
  • Naoki Isobe, Shingo Kashima, Yoshinori Suematsu, Naoteru Gouda, Ryohei Kano, Hirokazu Kataza, Hajime Kawahara, Naoki Kohara, Iona Kondo, Ichiro Masuda, Ryou Ohsawa, Toshihiro Tsuzuki, Fumihiko Usui, Shin Utsunomiya, Takehiko Wada, Yoshiyuki Yamada, Taihei Yano, Aoi Takahashi, Tomoya Hattori, Koichi Takeda, Yukina Arima
    SPACE TELESCOPES AND INSTRUMENTATION 2024: OPTICAL, INFRARED, AND MILLIMETER WAVE 13092 2024年  
    Structural, Thermal and Optical Performance (STOP) analysis is performed to investigate the stability of the telescope to be onboard the Japan Astrometry Satellite Mission for INfrared Exploration (JASMINE). In order to perform one of the prime science objectives, high-precision astrometric observations in the wavelength range of 1.0-1.6 mu m toward the Galactic center to reveal its central core structure and formation history, the JASMINE telescope is requested to be highly stable with an orbital change in the image distortion pattern being less than a few 10 mu as after low-order correction. The JASMINE telescope tried to satisfy this requirement by adopting two design concepts. Firstly, the mirror and their support structures are made of extremely low coefficient-of-thermal-expansion materials. Secondly, their temperatures are highly stabilized with an orbital variation of less the 0.1 degrees C by the unique thermal control idea. Through the preliminary STOP analysis, the structural and thermal structural feasibility of the JASMINE telescope is considered. By combining the results of the structural and thermal design, its thermal deformation is estimated. The optical performance of the JASMINE telescope after the thermal deformation is numerically evaluated. It is found that the thermal displacement of the mirrors in the current structural thermal design produces a slightly large focus-length change. As far as the focus adjustment is adequately applied, the orbital variation of the image distortion pattern is suggested to become acceptable after the low-order correction.
  • Kei Sano, Takao Nakagawa, Shuji Matsuura, Koji Takimoto, Aoi Takahashi, Tetsuhito Fuse, Rodrigo Cordova, Victor Hugo Schulz, Pooja Lepcha, Necmi Cihan Orger, Daisuke Nakayama, Joseph Ofosu, Reynel Josue Galindo Rosales, Eyoas Areda, Pema Zangmo, Ezra Fielding, Keenan Chatara, Yukihisa Otani, Hisataka Kawasaki, Bastien Morelle, John Paul Almonte, Shunsuke Nakagawa, Yuto Tome, Shohei Karaki, Chinathip Narongpun, Hari Ram Shrestha, Marco Rosa, David Dai, Wenceslao Bejarano, Akihiro Ikeda, Rin Sato, Kentaro Hayashida, Hiroki Miyagawa, Masahiro Nishio, Kana Kurosaki, Isami Kato, Satoshi Ikari, Kohji Tsumura, Ichiro Jikuya, Hideo Matsuhara, Umi Enokida, Hayato Tanaka, Yuki Hirose, Akimasa Ojika, Akane Tsumoto, Taiko Iwaki, Yuki Ohara, Mengu Cho, Kentaro Kitamura, Hirokazu Masui, Mariko Teramoto, Takashi Yamauchi, Ryo Hashimoto, Emino Fukumoto, Zamba Leonela, Arisa Oho, Shoki Yabumoto, Hayato Masuno, Chisato Arakawa, Kouta Miyamoto, Takehiko Wada, Naoki Isobe, Yasuyuki Miyazaki, Ryu Funase, Hajime Kawahara, Keiichi Hirako, Yoichi Yatsu, Yoshihide Aoyanagi
    SPACE TELESCOPES AND INSTRUMENTATION 2024: OPTICAL, INFRARED, AND MILLIMETER WAVE 13092 2024年  
    We describe scientific objective and project status of an a stronomical 6U CubeSat mission VERTECS (Visible Extragalactic background RadiaTion Exploration by CubeSat). The scientific goal of VERTECS is to reveal the star-formation history along the evolution of the universe by measuring the extragalactic background light (EBL) in the visible wavelength. Earlier observations have shown that the near-infrared EBL is several times brighter than integrated light of individual galaxies. As candidates for the excess light, first-generation stars in the early universe or low-redshift intra-halo light have been proposed. Since these objects are expected to show different emission spectra in visible wavelengths, multi-color visible observations are crucial to reveal the origin of the excess light. Since detection sensitivity of the EBL depends on the product of the telescope aperture and the field of view, it is possible to observe it with a small but wide-field telescope system that can be mounted on the limited volume of CubeSat. In VERTECS mission, we develop a 6U CubeSat equipped with a 3U-sized telescope optimized for observation of the visible EBL. The bus system composed of onboard computer, electric power system, communication subsystem, and structure is based on heritage of series of CubeSats developed at Kyushu Institute of Technology in combination with high-precision attitude control subsystem and deployable solar array paddle required for the mission. The VERTECS mission was selected for JAXA-Small Satellite Rush Program (JAXA-SMASH Program), a new program that encourages universities, private companies and JAXA to collaborate to realize small satellite missions utilizing commercial small launch opportunities, and to diversify transportation services in Japan. We started the satellite development in December 2022 and plan to launch the satellite in FY2025.
  • Aoi Takahashi, Takayuki Kotani, Jun Nishikawa, Akitoshi Ueda, Masayuki Kuzuhara, Motohide Tamura, Takahiro Nagayama, Mikio Kurita, Takahiro Sumi, Tomoyasu Yamamuro, Bun'ei Sato, Teruyuki Hirano, Masashi Omiya
    Ground-based and Airborne Instrumentation for Astronomy VIII 253-253 2020年12月28日  筆頭著者
  • Koji Takimoto, Seung-Cheol Bang, Priyadarshini Bangale, James J. Bock, Asantha Cooray, Kenta Danbayashi, Richard M. Feder, Masaki Furutani, Kevin Gates, Ryo Hashimoto, Viktor Hristov, Arisa Kida, Phillip Korngut, Alicia Lanz, Dae-Hee Lee, Lunjun Liu, Peter Mason, Toshio Matsumoto, Shuji Matsuura, Jodi-Ann Morgan, Chi H. Nguyen, Won-Kee Park, Dorin Patru, James Parkus, Shohta Sakai, Kei Sano, Hiroko Suzuki, Aoi Takahashi, Sohta Tatsu, Kohji Tsumura, Takehiko Wada, Shiang-Yu Wang, Yasuhiro Yamada, Michael Zemcov
    Space Telescopes and Instrumentation 2020: Optical, Infrared, and Millimeter Wave 2020年12月13日  
  • Aoi Takahashi, Takafumi Ootsubo, Hideo Matsuhara, Itsuki Sakon, Fumihiko Usui, Hiroki Chihara
    PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN 71(6) 2019年12月  筆頭著者
    Interplanetary dust (IPD) is thought to be recently supplied from asteroids and comets. Grain properties of the IPD can give us information about the environment in the protosolar system, and can be traced from the shapes of silicate features around 10 mu m seen in the zodiacal emission spectra. We analyzed mid-infrared slit-spectroscopic data of the zodiacal emission in various sky directions obtained with the Infrared Camera on board the Japanese AKARI satellite. After we subtracted the contamination due to instrumental artifacts, we successfully obtained high signal-to-noise spectra and have determined detailed shapes of excess emission features in the 9-12 mu m range in all sky directions. According to a comparison between the feature shapes averaged over all directions and the absorption coefficients of candidate minerals, the IPD was found to typically include small silicate crystals, especially enstatite grains. We also found variations in the feature shapes and the related grain properties among the different sky directions. From investigations of the correlation between feature shapes and the brightness contributions from dust bands, the IPD in dust bands seems to have a size frequency distribution biased toward large grains and shows indications of hydrated minerals. The spectra at higher ecliptic latitudes showed a stronger excess, which indicates an increase in the fraction of small grains included in the line of sight at higher ecliptic latitudes. If we focus on the dependence of detailed feature shapes on ecliptic latitudes, the IPD at higher ecliptic latitudes was found to have a lower olivine/(olivine + pyroxene) ratio for small amorphous grains. The variation of the mineral composition of the IPD in different sky directions may imply different properties of the IPD from different types of parent bodies, because the spatial distribution of the IPD depends on the type of the parent body.
  • Aoi Takahashi, Keigo Enya, Kanae Haze, Hirokazu Kataza, Takayuki Kotani, Hideo Matsuhara, Tomohiro Kamiya, Tomoyasu Yamamuro, Paul Bierden, Steven Cornelissen, Charlie Lam, Michael Feinberg
    Applied Optics 56(23) 6694-6694 2017年8月10日  筆頭著者

講演・口頭発表等

 3

所属学協会

 2

共同研究・競争的資金等の研究課題

 5