研究者業績
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・宇宙物理学研究系 教授東京大学 大学院理学系研究科 物理学専攻 教授
- 学位
- 博士(理学)(東京大学)修士(理学)(東京大学)
- J-GLOBAL ID
- 200901060914122911
- researchmap会員ID
- 1000363024
- 外部リンク
研究キーワード
5研究分野
1委員歴
3-
2014年4月 - 現在
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2011年9月 - 現在
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2006年 - 2009年
受賞
2論文
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Astronomy & Astrophysics 2023年10月
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The Astrophysical Journal 2023年8月1日
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The Astrophysical Journal 2023年7月1日
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The Astronomical Journal 165(4) 162-162 2023年3月17日Abstract The Subaru telescope is currently performing a strategic program (SSP) using the high-precision near-infrared (NIR) spectrometer IRD to search for exoplanets around nearby mid/late M dwarfs via radial velocity (RV) monitoring. As part of the observing strategy for the exoplanet survey, signatures of massive companions such as RV trends are used to reduce the priority of those stars. However, this RV information remains useful for studying the stellar multiplicity of nearby M dwarfs. To search for companions around such “deprioritized” M dwarfs, we observed 14 IRD-SSP targets using Keck/NIRC2 with pyramid wave-front sensing at NIR wavelengths, leading to high sensitivity to substellar-mass companions within a few arcseconds. We detected two new companions (LSPM J1002+1459 B and LSPM J2204+1505 B) and two new candidates that are likely companions (LSPM J0825+6902 B and LSPM J1645+0444 B), as well as one known companion. Including two known companions resolved by the IRD fiber injection module camera, we detected seven (four new) companions at projected separations between ∼2 and 20 au in total. A comparison of the colors with the spectral library suggests that LSPM J2204+1505 B and LSPM J0825+6902 B are located at the boundary between late M and early L spectral types. Our deep high-contrast imaging for targets where no bright companions were resolved did not reveal any additional companion candidates. The NIRC2 detection limits could constrain potential substellar-mass companions (∼10–75 MJup) at 10 au or further. The failure with Keck/NIRC2 around the IRD-SSP stars having significant RV trends makes these objects promising targets for further RV monitoring or deeper imaging with the James Webb Space Telescope to search for smaller-mass companions below the NIRC2 detection limits.
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The Astronomical Journal 2023年2月1日
MISC
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Proceedings of SPIE - The International Society for Optical Engineering 3356 462-470 1998年We present a conceptual design of a future Japanese infrared astronomical sateffite: the fflI/L2 mission. We propose a warm launch cooled telescope; the telescope is to be launched at ambient temperature and is to be cooled in orbit to 4.5K by a modest cryogenic cooler with the help of radiative cooling. Since liquid helium and hence a heavy vacuum vessel are no longer required, the warm launch design reduces the weight of the sateffite dramatically. We propose to launch this sateffite into a halo orbit around S-E L2, one of the Sun-Earth Lagrangian liberation points. The S-E L2 is an ideal orbit for infrared astronomy, since (1) radiative cooling can become very effective, and (2) long-integration observations become possible. A 3.5 m class telescope can be put into a halo orbit around S-E L2 by the Japanese H-hA launching vehicle. This mission focuses on high-resolution mid-to far-infrared observations with unprecedented sensitivity, since the large aperture reduces confusion noise and the cooled optics suppresses instrumental background radiation. The fflh/L2 mission is an ideal observatory-type platform to make follow-up observations to the ASTRO-F/IIUS survey mission. The target launch year is 2010.
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DIFFUSE INFRARED RADIATION AND THE IRTS 124 287-290 1997年We observed a central part of the Cygnus X region (8 degrees x 5 degrees) by the [C II] 158 mu m line with a 15' resolution. An intense [C II] line emission (greater than or equal to 3 x 10(-5) ergs cm(-2)s(-1) sr(-1)) was detected from the whole observed region. The measured emission consists of more than ten compact sources, which can be identified as known H II regions, and a spatially diffuse component (diffuse [C II] emission). The diffuse [C II] emission distributes throughout the observed region and dominates the measured emission. This component shows good spatial correlationships with far-infrared continuum and radio thermal continuum emissions, while a spatial correlation with CO (1 --> 0) line emission is poor. The correlationship with the radio continuum emission is good in the whole observed region whose actual diameter is more than 100 pc. We conclude that the most natural description of this correlationship is to attribute the diffuse [CII] emission to ionized gas.
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European Space Agency, (Special Publication) ESA SP (401) 313-316 1997年We have been making survey observations of the far-infrared [C II] Une ( P → P , 157.7409 μm) using a balloon-borne telescope BICE (Balloon-borne Infrared Carbon Explorer). Our survey covers wide areas (total ∼ 1000 deg ) with a moderate resolution (15′). Our observations covered various objects: most of the inner Galactic plane (260° ≤ l ≤ 60°, |b| ≤ 3°), star-forming regions with O-type stars (Cyg-X region and Orion region) or without O-type stars (ρ-Ophiuchi dark cloud), and main part of the Large Magellanic Cloud. Main results of the observations are briefly reviewed. 2 2 2 3/2 1/2
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Publications of the Astronomical Society of Japan 49(2) 179-185 1997年We report on ASCA observations of two ultraluminous far-infrared galaxies, IRAS 15307+3252 and IRAS 20460+1925. An X-ray flux of 1.53 × 10 erg cm s in the 2-10 keV band was detected from IRAS 20460+1925. The continuous spectrum is well represented by a power law with a photon index of 1.99 and excess photoelectric absorption by a column of (2.6 ) × 10 cm in the rest frame. The spectrum also shows an iron K emission line with an equivalent width of 260 eV and a centroid energy of 6.36±0.08 keV in the rest frame. These spectral properties are consistent with those of Seyfert-2 galaxies, although the intrinsic 2-10 keV X-ray luminosity (corrected for absorption) of 1.20 × 10 erg s is high and close to that of quasars. No X-rays were detected from IRAS 15307+3252, and the upper limit to the X-ray flux is 7.2 × 10 erg cm s in the 2-10 keV band. However, the upper limit on the ratio of the X-ray flux to the far-infrared flux is not inconsistent with a source containing a highly obscured quasar. -12 -2 -1 +0.18 +0.29 22 -2 +145 44 -1 -14 -2 -1 -0.15 -0.32 -137
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宇宙科学研究所報告 特集 33(33) 57-75 1996年3月オリオン領域の[CII] 158μm輝線サーベイ観測を,気球搭載望遠鏡BICE (Balloon-borne Infrared Carbon Explorer)によって行った。観測領域は12°×8°に及び,COBEの観測を除けばこれまでに観測された領域の数百倍である。この観測の結果,オリオン領域には広い範囲に[CII] 158μm輝線の輻射成分が存在することが明らかになった。また,[CII] 158μm輝線と遠赤外線連続波とCO (J=1-0)を比較すると,場所によってそのお互いの強度比が大きな相違を示す。このことは,オリオン領域での[CII] 158μm輝線放射が多様な物理状態の星間ガスから行われていることを示唆する。資料番号: SA0167070000
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Astrophysical Journal 455(1) L35-L38 1995年12月10日We have observed the [C ii] 158 μm line emission from the Galactic plane (— 10° < l < 25°, < 3°) with the Balloon-borne Infrared Carbon Explorer (BICE). The observed longitudinal distribution of the [C ii] line emission is clearly different from that of the far-infrared continuum emission; the Galactic center is not the dominant peak in the [C ii] emission. Indeed, the ratio of the [C ii] line emission to that of the far-infrared continuum (I /I ) is systematically low within the central several hundred parsecs of the Galaxy. The observational results indicate that the abundance of the C ions themselves is low in the Galactic center. We attribute this low abundance mainly to soft uV radiation with fewer C-ionizing photons. This soft radiation field, together with the pervasively high molecular gas density, makes the molecular self-shielding more effective in the Galactic center. The self-shielding further reduces the abundance of C ions, and raises the temperature of molecular gas at the C /C/CO transition zone. © 1995. The American Astronomical Society. All rights reserved. Printed in U.S.A. [CII] FIR + + +
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宇宙科学研究所報告. 特集: 大気球研究報告 32(32) 89-103 1995年3月星間ガスのエネルギー収支に最も重要な役割を果たす遠赤外[CII]スペクトル線を, 広い領域にわたってサーベイ観測するために, 専用機BICE (Balloon-borne Infrared Carbon Explorer)を開発し, これを用いて海外観測遠征実験を2回行った。これらの実験により, 銀河面の広い範囲(255°≲l≲78°, |b|≲3°), Cygnus-X領域, ρ Ophiuchi暗黒星雲, 大マゼラン雲などが, [CII]輝線によりマッピング観測された。観測の結果, 光解離領域に代表されるようなあたたかな星間物質の, 様々な存在形態が明らかになった。資料番号: SA0167058000
共同研究・競争的資金等の研究課題
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日本学術振興会 科学研究費助成事業 2023年4月 - 2028年3月
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日本学術振興会 科学研究費助成事業 2023年4月 - 2027年3月
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日本学術振興会 科学研究費助成事業 2024年4月 - 2027年3月
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日本学術振興会 科学研究費助成事業 2023年4月 - 2026年3月
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日本学術振興会 科学研究費助成事業 2023年6月 - 2025年3月
● 専任大学名
1-
専任大学名東京大学（University of Tokyo)
