2021/09/24 更新

写真a

シモニシ タカシ
下西 隆
SHIMONISHI Takashi
所属
研究推進機構 超域学術院 助教
職名
助教
外部リンク

学位

  • 博士(理学) ( 2012年3月   東京大学 )

  • 修士(理学) ( 2009年3月   東京大学 )

研究キーワード

  • 金属量

  • 分子雲

  • 原始星

  • 星間化学

  • 星間塵

  • 星間分子

  • 星間氷

  • 星間物質

  • マゼラン雲

  • ホットコア

  • 星形成

  • 近傍銀河

  • VLT

  • 「あかり」衛星

  • ALMA

  • 電波天文学

  • 分子分光

  • 複雑有機分子

  • 赤外線天文学

研究分野

  • 自然科学一般 / 天文学

経歴(researchmap)

  • 新潟大学   研究推進機構 超域学術院   助教

    2019年11月 - 現在

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  • 東北大学   学際科学フロンティア研究所   助教

    2015年1月 - 2019年10月

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  • 神戸大学   大学院理学研究科地球惑星科学専攻   日本学術振興会特別研究員PD

    2012年4月 - 2014年12月

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  • 東京大学   大学院理学系研究科 天文学専攻   日本学術振興会特別研究員DC2

    2010年4月 - 2012年3月

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経歴

  • 新潟大学   研究推進機構 超域学術院   助教

    2019年11月 - 現在

学歴

  • 東京大学   大学院理学系研究科   天文学専攻 博士課程

    2009年4月 - 2012年3月

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  • 東京大学   大学院理学系研究科   天文学専攻 修士課程

    2007年4月 - 2009年3月

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  • 東北大学   理学部   宇宙地球物理学科 地球物理学専攻

    2003年4月 - 2007年3月

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所属学協会

 

論文

  • Discovery of Two Infrared Objects with Strong Ice Absorption in the Akari Slitless Spectroscopic Survey of the Galactic Plane 査読

    Takashi Onaka, Tomoyuki Kimura, Itsuki Sakon, Takashi Shimonishi

    The Astrophysical Journal   916 ( 2 )   75 - 75   2021年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:American Astronomical Society  

    DOI: 10.3847/1538-4357/ac0531

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    その他リンク: https://iopscience.iop.org/article/10.3847/1538-4357/ac0531/pdf

  • Formation of chiral CO polyhedral crystals on icy interstellar grains 査読

    Akira Kouchi, Masashi Tsuge, Tetsuya Hama, Hiromasa Niinomi, Naoki Nakatani, Takashi Shimonishi, Yasuhiro Oba, Yuki Kimura, Sin-iti Sirono, Satoshi Okuzumi, Munetake Momose, Kenji Furuya, Naoki Watanabe

    Monthly Notices of the Royal Astronomical Society   505 ( 1 )   1530 - 1542   2021年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Oxford University Press (OUP)  

    <title>ABSTRACT</title>
    The crystallinity and morphology of solid carbon monoxide (CO) on icy interstellar grains were examined by observing the deposition, crystallization, and UV and electrons irradiation of solid CO using transmission electron microscopy. Herein, we found that solid CO deposited in molecular clouds was crystalline, and that even if amorphous CO was deposited, amorphous CO crystallized within 103 yr at 10 K. Conversely, crystalline CO was not amorphized by UV rays or electron beam at 10 K. These results indicated the occurrence of chiral crystalline CO instead of amorphous CO in space. Furthermore, the large surface diffusion coefficients of CO on eamorphous H2O and crystalline CO at 10 K facilitated the morphological equilibration of crystalline CO. Bad wetting of crystalline CO with amorphous H2O proved that the morphology of the ice grains was not spherical with an onion-like structure, as hitherto assumed, but rather it was a polyhedral crystalline CO attached to amorphous H2O. This has important implications for phenomena associated with the collision and subsequent sticking between ice grains, surface chemical reactions, non-thermal desorption of molecules and the origin of homochirality in interstellar biomolecules.

    DOI: 10.1093/mnras/stab1173

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    その他リンク: http://academic.oup.com/mnras/article-pdf/505/1/1530/38463480/stab1173.pdf

  • Identification of Methyl Isocyanate and Other Complex Organic Molecules in a Hot Molecular Core, G31.41+0.31 査読

    Prasanta Gorai, Ankan Das, Takashi Shimonishi, Dipen Sahu, Suman Kumar Mondal, Bratati Bhat, Sandip K. Chakrabarti

    The Astrophysical Journal   907 ( 108 )   1 - 22   2021年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

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  • An Experimental Study of Chemical Desorption for Phosphine in Interstellar Ice 査読

    Thanh Nguyen, Yasuhiro Oba, Takashi Shimonishi, Akira Kouchi, Naoki Watanabe

    The Astrophysical Journal   898 ( 2 )   L52 - L52   2020年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:American Astronomical Society  

    DOI: 10.3847/2041-8213/aba695

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    その他リンク: https://iopscience.iop.org/article/10.3847/2041-8213/aba695

  • Systematic Study on the Absorption Features of Interstellar Ices in the Presence of Impurities 査読

    Prasanta Gorai, Milan Sil, Ankan Das, Bhalamurugan Sivaraman, Sandip K. Chakrabarti, Sergio Ioppolo, Cristina Puzzarini, Zuzana Kanuchova, Anita Dawes, Marco Mendolicchio, Giordano Mancini, Vicenzo Barone, Naoki Nakatani, Takashi Shimonishi, Nigel Mason

    ACS Earth and Space Chemistry   4 ( 6 )   920 - 946   2020年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:American Chemical Society (ACS)  

    DOI: 10.1021/acsearthspacechem.0c00098

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  • Chemistry and physics of a low-metallicity hot core in the Large Magellanic Cloud 査読

    Takashi Shimonishi, Ankan Das, Nami Sakai, Kei E. I. Tanaka, Yuri Aikawa, Takashi Onaka, Yoshimasa Watanabe, Yuri Nishimura

    The Astrophysical Journal   891 ( 164 )   1 - 24   2020年3月

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    担当区分:筆頭著者, 責任著者   記述言語:英語   掲載種別:研究論文(学術雑誌)  

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  • Complex Organic Molecules in Star-Forming Regions of the Magellanic Clouds 査読

    Marta Sewilo, Steven B. Charnley, Peter Schilke, Vianney Taquet, Joana M. Oliveira, Takashi Shimonishi, Eva Wirström, Remy Indebetouw, Jacob L. Ward, Jacco Th. van Loon, Jennifer Wiseman, Sarolta Zahorecz, Toshikazu Onishi, Akiko Kawamura, C. -H. Rosie Chen, Yasuo Fukui, Roya Hamedani Golshan

    ACS Earth and Space Chemistry   3 ( 10 )   2088 - 2109   2019年10月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

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  • Molecular-cloud-scale Chemical Composition. III. Constraints of Average Physical Properties through Chemical Models 査読

    Harada Nanase, Nishimura Yuri, Watanabe Yoshimasa, Yamamoto Satoshi, Aikawa Yuri, Sakai Nami, Shimonishi Takashi

    The Astrophysical Journal   871 ( 2 )   1 - 24   2019年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.3847/1538-4357/aaf72a

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  • A Multiline Study of a High-mass Young Stellar Object in the Small Magellanic Cloud with ALMA: The Detection of Methanol Gas at 0.2 Solar Metallicity 査読

    Takashi Shimonishi, Yoshimasa Watanabe, Yuri Nishimura, Yuri Aikawa, Satoshi Yamamoto, Takashi Onaka, Nami Sakai, Akiko Kawamura

    The Astrophysical Journal   862 ( 102 )   1 - 14   2018年7月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.3847/1538-4357/aacd0c

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  • Adsorption Energies of Carbon, Nitrogen, and Oxygen Atoms on the Low-temperature Amorphous Water Ice: A Systematic Estimation from Quantum Chemistry Calculations 査読

    Takashi Shimonishi, Naoki Nakatani, Kenji Furuya, Tetsuya Hama

    Astrophysical Journal   855 ( 1 )   1 - 11   2018年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Institute of Physics Publishing  

    We propose a new simple computational model to estimate the adsorption energies of atoms and molecules to low-temperature amorphous water ice, and we present the adsorption energies of carbon (3 P), nitrogen (4 S), and oxygen (3 P) atoms based on quantum chemistry calculations. The adsorption energies were estimated to be 14,100 ±420 K for carbon, 400 ±30 K for nitrogen, and 1440 ±160 K for oxygen. The adsorption energy of oxygen is consistent with experimentally reported values. We found that the binding of a nitrogen atom is purely physisorption, while that of a carbon atom is chemisorption, in which a chemical bond to an O atom of a water molecule is formed. That of an oxygen atom has a dual character, with both physisorption and chemisorption. The chemisorption of atomic carbon also implies the possibility of further chemical reactions to produce molecules bearing a C-O bond, though this may hinder the formation of methane on water ice via sequential hydrogenation of carbon atoms. These properties would have a large impact on the chemical evolution of carbon species in interstellar environments. We also investigated the effects of newly calculated adsorption energies on the chemical compositions of cold dense molecular clouds with the aid of gas-ice astrochemical simulations. We found that abundances of major nitrogen-bearing molecules, such as N2 and NH3, are significantly altered by applying the calculated adsorption energy, because nitrogen atoms can thermally diffuse on surfaces, even at 10 K.

    DOI: 10.3847/1538-4357/aaaa6a

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  • Molecular-cloud-scale Chemical Composition. II. Mapping Spectral Line Survey toward W3(OH) in the 3mm Band 査読

    Yuri Nishimura, Yoshimasa Watanabe, Nanase Harada, Takashi Shimonishi, Nami Sakai, Yuri Aikawa, Akiko Kawamura, Satoshi Yamamoto

    ASTROPHYSICAL JOURNAL   848 ( 1 )   1 - 17   2017年10月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IOP PUBLISHING LTD  

    To study a molecular-cloud-scale chemical composition, we conducted a mapping spectral line survey toward the Galactic molecular cloud W3(OH), which is one of the most active star-forming regions in the Perseus arm. We conducted our survey through the use of the Nobeyama Radio Observatory 45 m telescope, and observed the area of 16' x 16', which corresponds to 9.0 pc x 9.0 pc. The observed frequency ranges are 87-91, 96-103, and 108-112 GHz. We prepared the spectrum averaged over the observed area, in which eight molecular species (CCH, HCN, HCO+, HNC, CS, SO, (CO)-O-18, and (CO)-C-13) are identified. On the other hand, the spectrum of the W3(OH) hot core observed at a 0.17 pc resolution shows the lines of various molecules such as OCS, H2CS CH3CCH, and CH3CN in addition to the above species. In the spatially averaged spectrum, emission of the species concentrated just around the star-forming core, such as CH3OH and HC3N, is fainter than in the hot core spectrum, whereas emission of the species widely extended over the cloud such as CCH is relatively brighter. We classified the observed area into five subregions according to the integrated intensity of (CO)-C-13, and evaluated the contribution to the averaged spectrum from each subregion. The CCH, HCN, HCO+, and CS lines can be seen even in the spectrum of the subregion with the lowest (CO)-C-13 integrated intensity range (&lt; 10 K km s(-1)). Thus, the contributions of the spatially extended emission is confirmed to be dominant in the spatially averaged spectrum.

    DOI: 10.3847/1538-4357/aa89e5

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  • Molecular-cloud-scale Chemical Composition. I. A Mapping Spectral Line Survey toward W51 in the 3mm Band 査読

    Yoshimasa Watanabe, Yuri Nishimura, Nanase Harada, Nami Sakai, Takashi Shimonishi, Yuri Aikawa, Akiko Kawamura, Satoshi Yamamoto

    ASTROPHYSICAL JOURNAL   845 ( 2 )   1 - 29   2017年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IOP PUBLISHING LTD  

    We have conducted a mapping spectral line survey toward the Galactic giant molecular cloud W51 in the 3mm band with the Mopra 22m telescope in order to study an averaged chemical composition of the gas extended over a molecular-cloud scale in our Galaxy. We have observed the area of 25'x30', which corresponds to 39 pcx47 pc. The frequency ranges of the observation are 85.1-101.1 GHz and 107.0-114.9 GHz. In the spectrum spatially averaged over the observed area, spectral lines of 12 molecular species and 4 additional isotopologues are identified. An intensity pattern of the spatially averaged spectrum is found to be similar to that of the spiral arm in the external galaxy M51, indicating that these two sources have similar chemical compositions. The observed area has been classified into five subregions according to the integrated intensity of (CO)-C-13( J =1-0) ( I-13CO), and contributions of the fluxes of 11 molecular lines from each subregion to the averaged spectrum have been evaluated. For most of the molecular species, 50% or more of the flux comes from the subregions with I13CO from 25 to 100Kkms(-1), which does not involve active star-forming regions. Therefore, the molecular-cloudscale spectrum observed in the 3mm band hardly represents the chemical composition of star-forming cores, but mainly represents the chemical composition of an extended quiescent molecular gas. The present result constitutes a sound base for interpreting the spectra of external galaxies at a resolution of a molecular-cloud scale (similar to 10pc) or larger.

    DOI: 10.3847/1538-4357/aa7ece

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  • Ice Absorption Features in NIR Spectra of Galactic Objects 査読

    Mori Tamami I, Onaka Takashi, Sakon Itsuki, Ohsawa Ryou, Kaneda Hidehiro, Yamagishi Mitsuyoshi, Okada Yoko, Tanaka Masahiro, Shimonishi, Takashi

    Publications of The Korean Astronomical Society   32 ( 1 )   105 - 107   2017年3月

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    DOI: 10.5303/PKAS.2017.32.1.105

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  • Processing of Interstellar Medium as Divulged by Akari 査読

    Onaka Takashi, Mori Tamami I, Ohsawa Ryou, Sakon Itsuki, Bell Aaron C, Hammonds Mark, Shimonishi Takashi, Ishihara Daisuke, Kaneda Hidehiro, Okada Yoko, Tanaka Masahiro

    Publications of The Korean Astronomical Society   32 ( 1 )   77 - 81   2017年3月

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    DOI: 10.5303/PKAS.2017.32.1.077

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  • AKARI Infrared Camera Survey of the Large Magellanic Cloud 査読

    Shimonishi Takashi, Kato Daisuke, Ita Yoshifusa, Onaka Takashi, AKARI/IRC LMC Team

    Publications of The Korean Astronomical Society   32 ( 1 )   83 - 85   2017年3月

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    DOI: 10.5303/PKAS.2017.32.1.083

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  • Study of CO2/H2O Ice Abundance Ratios in Nearby Galaxies with the Akari Near-Infrared Spectroscopy 査読

    Yamagishi Mitsuyoshi, Kaneda Hidehiro, Oyabu Shinki, Ishihara Daisuke, Onaka Takashi, Shimonishi Takashi, Suzuki Toyoaki

    Publications of The Korean Astronomical Society   32 ( 1 )   141 - 145   2017年3月

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)  

    DOI: 10.5303/PKAS.2017.32.1.141

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  • SPECTRAL LINE SURVEY TOWARD A MOLECULAR CLOUD IN IC10 査読

    Yuri Nishimura, Takashi Shimonishi, Yoshimasa Watanabe, Nami Sakai, Yuri Aikawa, Akiko Kawamura, Satoshi Yamamoto

    ASTROPHYSICAL JOURNAL   829 ( 2 )   1 - 8   2016年10月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IOP PUBLISHING LTD  

    We have conducted a spectral line survey observation in the 3 mm band toward the low-metallicity dwarf galaxy IC10 with the 45 m radio telescope of the Nobeyama Radio Observatory to explore its chemical composition at a molecular-cloud scale (similar to 80 pc). The CS, SO, CCH, HCN, HCO+, and HNC lines are detected for the first time in this galaxy in addition to the CO and (CO)-C-13 lines, while the c-C3H2, CH3OH, CN, (CO)-O-18, and N2H+ lines are not detected. The spectral intensity pattern is found to be similar to those observed toward molecular clouds in the Large Magellanic Cloud (LMC), whose metallicity is as low as IC10. Nitrogen-bearing species are deficient in comparison with the Galactic molecular clouds due to a lower elemental abundance of nitrogen. CCH is abundant in comparison with Galactic translucent clouds, whereas CH3OH may be deficient. These characteristic trends for CCH and CH3OH are also seen in the LMC, and seem to originate from photodissociation regions more extended in the peripheries of molecular clouds due to the lower metallicity condition.

    DOI: 10.3847/0004-637X/829/2/94

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  • THE DETECTION OF A HOT MOLECULAR CORE IN THE LARGE MAGELLANIC CLOUD WITH ALMA 査読

    Takashi Shimonishi, Takashi Onaka, Akiko Kawamura, Yuri Aikawa

    ASTROPHYSICAL JOURNAL   827 ( 1 )   1 - 20   2016年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IOP PUBLISHING LTD  

    We report the first detection of a hot molecular core outside our Galaxy based on radio observations with ALMA toward a high-mass young stellar object (YSO) in a nearby low metallicity galaxy, the Large Magellanic Cloud (LMC). Molecular emission lines of CO, (CO)-O-17, HCO+, (HCO+)-C-13, H2CO, NO, SiO, H2CS, (SO)-S-33, (SO2)-S-32, (SO2)-S-34, and (SO2)-S-33 are detected from a compact region (similar to 0.1 pc) associated with a high-mass YSO, ST11. The temperature of molecular gas is estimated to be higher than 100 K based on rotation diagram analysis of SO2 and (SO2)-S-34 lines. The compact source size, warm gas temperature, high density, and rich molecular lines around a high-mass protostar suggest that ST11 is associated with a hot molecular core. We find that the molecular abundances of the LMC hot core are significantly different from those of Galactic hot cores. The abundances of CH3OH, H2CO, and HNCO are remarkably lower compared to Galactic hot cores by at least 1-3 orders of magnitude. We suggest that these abundances are characterized by the deficiency of molecules whose formation requires the hydrogenation of CO on grain surfaces. In contrast, NO shows a high abundance in ST11 despite the notably low abundance of nitrogen in the LMC. A multitude of SO2 and its isotopologue line detections in ST11 imply that SO2 can be a key molecular tracer of hot core chemistry in metal-poor environments. Furthermore, we find molecular outflows around the hot core, which is the second detection of an extragalactic protostellar outflow. In this paper, we discuss the physical and chemical characteristics of a hot molecular core in the low metallicity environment.

    DOI: 10.3847/0004-637X/827/1/72

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  • SPECTRAL LINE SURVEY TOWARD MOLECULAR CLOUDS IN THE LARGE MAGELLANIC CLOUD 査読

    Yuri Nishimura, Takashi Shimonishi, Yoshimasa Watanabe, Nami Sakai, Yuri Aikawa, Akiko Kawamura, Satoshi Yamamoto

    ASTROPHYSICAL JOURNAL   818 ( 2 )   1 - 17   2016年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IOP PUBLISHING LTD  

    Spectral line survey observations of seven. molecular clouds in the Large Magellanic Cloud (LMC) have been conducted in the 3 mm band with the Mopra 22 m telescope to reveal chemical compositions in low metallicity conditions. Spectral lines of fundamental species such as CS, SO, CCH, HCN, HCO+, and HNC are detected in addition to those of CO and (CO)-C-13, while CH3OH is not detected in any source and N2H+ is marginally detected in two sources. The molecular-cloud scale (10 pc scale) chemical composition is found to be similar among the seven. sources regardless of different star formation activities, and hence, it represents the chemical composition characteristic of. the LMC without influences by. star formation activities. In comparison with chemical compositions of Galactic sources, the characteristic features are (1) deficient N-bearing molecules, (2) abundant CCH, and (3) deficient CH3OH. Feature (1) is due to a lower elemental abundance of nitrogen in the LMC, whereas. features (2) and (3) seem to originate from extended photodissociation regions and warmer temperature in cloud peripheries due to a lower abundance of dust grains in the low metallicity condition. In spite of general resemblance of chemical abundances among the seven sources, the CS/HCO+ and SO/HCO+ ratios are found to be slightly higher in a quiescent molecular cloud. An origin of this trend is discussed in relation to possible depletion of sulfur along the molecular cloud formation.

    DOI: 10.3847/0004-637X/818/2/161

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  • CONCURRENT FORMATION OF CARBON AND SILICATE DUST IN NOVA V1280 SCO 査読

    Itsuki Sakon, Shigeyuki Sako, Takashi Onaka, Takaya Nozawa, Yuki Kimura, Takuya Fujiyoshi, Takashi Shimonishi, Fumihiko Usui, Hidenori Takahashi, Ryou Ohsawa, Akira Arai, Makoto Uemura, Takahiro Nagayama, Bon-Chul Koo, Takashi Kozasa

    ASTROPHYSICAL JOURNAL   817 ( 2 )   1 - 23   2016年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IOP PUBLISHING LTD  

    We present infrared multi-epoch observations of the dust-forming nova V1280 Sco over similar to 2000 days from the outburst. The temporal evolution of the infrared spectral energy distributions at 1272, 1616, and 1947 days can be explained by the emissions produced by amorphous carbon dust of mass (6.6-8.7) x 10(-8) M-circle dot with a representative grain size of 0.01. mu m and astronomical silicate dust of mass (3.4-4.3) x 10(-7) M-circle dot with a representative grain size of 0.3-0.5 mu m. Both of these dust species travel farther away from the white dwarf without apparent mass evolution throughout those later epochs. The dust formation scenario around V1280 Sco suggested from our analyses is that the amorphous carbon dust is formed in the nova ejecta followed by the formation of silicate dust either in the expanding nova ejecta or as a result of the interaction between the nova wind and the circumstellar medium.

    DOI: 10.3847/0004-637X/817/2/145

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  • VLT/ISAAC infrared spectroscopy of embedded high-mass YSOs in the Large Magellanic Cloud: Methanol and the 3.47 μm band 査読

    Takashi Shimonishi, Emmanuel Dartois, Takashi Onaka, Francois Boulanger

    Astronomy and Astrophysics   585 ( A107 )   1 - 20   2016年1月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    DOI: 10.1051/0004-6361/201526559

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  • Carbon and silicate dust formation in V1280 Sco 査読

    I. Sakon, S. Sako, T. Oanaka, T. Nozawa, Y. Kimura, T. Fujiyoshi, T. Shimonishi, F. Usui, H. Takahashi, R. Ohsawa, A. Arai, M. Uemura, T. Nagayama, B-C Koo, T. Kozasa

    11TH PACIFIC RIM CONFERENCE ON STELLAR ASTROPHYSICS: PHYSICS AND CHEMISTRY OF THE LATE STAGES OF STELLAR EVOLUTION, PTS 1-6   728   062006   2016年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:IOP PUBLISHING LTD  

    This study investigates the temporal evolution of the infrared emission from the dusty nova V1280 Sco over 2000 days from the outburst. We have revealed that the infrared spectral energy distributions at 1272, 1616 and 1947 days are explained by the emissions produced by amorphous carbon dust of mass (6.6-8.7) x10(-8) M circle dot with a representative grain size of 0.01 mu m and astronomical silicate dust of mass (3.4-4.3) x10(-7) M circle dot with a representative grain size of 0.3-0.5 mu m. Both of carbon and silicate dust travel farther away from the white dwarf without an apparent mass evolution throughout those later epochs.

    DOI: 10.1088/1742-6596/728/6/062006

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  • SYSTEMATIC VARIATIONS IN CO2/H2O ICE ABUNDANCE RATIOS IN NEARBY GALAXIES FOUND WITH AKARI NEAR-INFRARED SPECTROSCOPY 査読

    M. Yamagishi, H. Kaneda, D. Ishihara, S. Oyabu, T. Onaka, T. Shimonishi, T. Suzuki

    ASTROPHYSICAL JOURNAL   807 ( 1 )   1 - 7   2015年7月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IOP PUBLISHING LTD  

    We report CO2/H2O ice abundance ratios in seven nearby star-forming galaxies based on the AKARI near-infrared (2.5-5.0 mu m) spectra. The CO2/H2O ice abundance ratios show clear variations between 0.05 and 0.2 with the averaged value of 0.14 +/- 0.01. The previous study on M82 revealed that the CO2/H2O ice abundance ratios strongly correlate with the intensity ratios of the hydrogen recombination Bra line to the polycyclic aromatic hydrocarbon (PAH) 3.3 mu m feature. In the present study, however, we find no correlation for the seven galaxies as a whole due to systematic differences in the relation between CO2/H2O ice abundance and Bra/PAH 3.3 mu m intensity ratios from galaxy to galaxy. This result suggests that there is another parameter that determines the CO2/H2O ice abundance ratios in a galaxy in addition to the Bra/PAH 3.3 mu m ratios. We find that the CO2/H2O ice abundance ratios positively correlate with the specific star formation rates of the galaxies. From these results, we conclude that CO2/H2O ice abundance ratios tend to be high in young star-forming galaxies.

    DOI: 10.1088/0004-637X/807/1/29

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  • AKARI NIR spectroscopy of interstellar ices

    Takashi Onaka, Tamami I. Mori, Itsuki Sakon, Fumihiko Usui, Ronin Wu, Takashi Shimonishi

    Proceedings of the International Astronomical Union   11 ( 1 )   319 - 320   2015年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:Cambridge University Press  

    The Infrared Camera (IRC) onboard AKARI has a near-infrared (2-5μm) spectroscopic capability with high sensitivity that allows us to study the major ice components in various objects. In particular, H2O and CO2 ice absorption features have been detected towards nearby galaxies, including several young stellar objects (YSOs) in the Large Magellanic Cloud (LMC), as well as a number of HII region-PDR complexes for the first time by IRC spectroscopy. While observations in the LMC show a high ratio (~0.34) of the CO2 to H2O ice column densities, the ratios in Galactic HII-region-PDR complexes are in the range of 0.1-0.2, being compatible with those found in Galactic massive YSOs in previous studies. The good correlation supports concurrent formation of the two ice species on the grain surface and the higher ratio in the low-metallicity LMC suggests possible environmental effects in the formation process.

    DOI: 10.1017/S1743921316003161

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  • Spectral Line Survey Toward Quiescent Giant Molecular Clouds in the Large Magellanic Cloud 査読

    Yuri Nishimura, Takashi Shimonishi, Yoshimasa Watanabe, Nami Sakai, Yuri Aikawa, Akiko Kawamura, Satoshi Yamamoto

    REVOLUTION IN ASTRONOMY WITH ALMA: THE THIRD YEAR   499   165 - 166   2015年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:ASTRONOMICAL SOC PACIFIC  

    Spectral line survey observations in the 3 mm band have been conducted toward 7 molecular clouds in the Large Magellanic Cloud (LMC) with the Mopra 22 m telescope. Spectral lines of the fundamental species CCH, HCN, HCO+, HNC, CS, SO, and c-C3H2 are detected. Although the 7 sources are different in star-formation activities, chemical compositions averaged over the 10 pc beam are similar to one another. We find that N-bearing species are deficient and CCH is relatively abundant in comparison with metal-rich environments. In spite of overall similarity of the chemical compositions, we also find a trend that the CS/HCO+ and SO/HCO+ ratios are higher for starless clouds.

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  • ERRATUM: “OBSERVATIONAL STUDIES ON THE NEAR-INFRARED UNIDENTIFIED EMISSION BANDS IN GALACTIC H II REGIONS” (2014, ApJ, 784, 53) 査読

    Tamami I. Mori, Takashi Onaka, Itsuki Sakon, Daisuke Ishihara, Takashi Shimonishi, Ryou Ohsawa, Aaron C. Bell

    The Astrophysical Journal   792 ( 1 )   80   2014年9月

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    記述言語:英語   出版者・発行元:{IOP} Publishing  

    DOI: 10.1088/0004-637X/792/1/80

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  • Near-Infrared Spectroscopy of Diffuse Galactic Radiation with AKARI/IRC 査読

    Takashi Onaka, Tamami Mori, Itsuki Sakon, Ryou Ohsawa, Tomohiko Nakamura, Ho-Gyu Lee, Ingrid M. Koch, Takashi Shimonishi, Hidehiro Kaneda, Yoko Okada, Masahiro Tanaka

    Proceedings of The Life Cycle of Dust in the Universe: Observations, Theory, and Laboratory Experiments — PoS(LCDU2013)   2014年6月

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    出版者・発行元:Sissa Medialab  

    DOI: 10.22323/1.207.0112

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  • Spitzer Space Telescope spectra of post-AGB stars in the Large Magellanic Cloud - polycyclic aromatic hydrocarbons at low metallicities 査読

    Mikako Matsuura, Jeronimo Bernard-Salas, T. Lloyd Evans, Kevin M. Volk, Bruce J. Hrivnak, G. C. Sloan, You-Hua Chu, Robert Gruendl, Kathleen E. Kraemer, Els Peeters, R. Szczerba, P. R. Wood, Albert A. Zijlstra, S. Hony, Yoshifusa Ita, Devika Kamath, Eric Lagadec, Quentin A. Parker, Warren A. Reid, Takashi Shimonishi, H. Van Winckel, Paul M. Woods, F. Kemper, Margaret Meixner, M. Otsuka, R. Sahai, B. A. Sargent, J. L. Hora, Iain McDonald

    MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY   439 ( 2 )   1472 - 1493   2014年4月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:OXFORD UNIV PRESS  

    This paper reports variations of polycyclic aromatic hydrocarbons (PAHs) features that were found in Spitzer Space Telescope spectra of carbon-rich post-asymptotic giant branch (post-AGB) stars in the Large Magellanic Cloud (LMC). The paper consists of two parts. The first part describes our Spitzer spectral observing programme of 24 stars including post-AGB candidates. The latter half of this paper presents the analysis of PAH features in 20 carbon-rich post-AGB stars in the LMC, assembled from the Spitzer archive as well as from our own programme. We found that five post-AGB stars showed a broad feature with a peak at 7.7 mu m, that had not been classified before. Further, the 10-13 mu m PAH spectra were classified into four classes, one of which has three broad peaks at 11.3, 12.3 and 13.3 mu m rather than two distinct sharp peaks at 11.3 and 12.7 mu m, as commonly found in H ii regions. Our studies suggest that PAHs are gradually processed while the central stars evolve from post-AGB phase to planetary nebulae, changing their composition before PAHs are incorporated into the interstellar medium. Although some metallicity dependence of PAH spectra exists, the evolutionary state of an object is more significant than its metallicity in determining the spectral characteristics of PAHs for LMC and Galactic post-AGB stars.

    DOI: 10.1093/mnras/stt2495

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  • OBSERVATIONAL STUDIES ON THE NEAR-INFRARED UNIDENTIFIED EMISSION BANDS IN GALACTIC H II REGIONS 査読

    Tamami I. Mori, Takashi Onaka, Itsuki Sakon, Daisuke Ishihara, Takashi Shimonishi, Ryou Ohsawa, Aaron C. Bell

    ASTROPHYSICAL JOURNAL   784 ( 1 )   1 - 12   2014年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IOP PUBLISHING LTD  

    Using a large collection of near-infrared spectra (2.5-5.4 mu m) of Galactic H II regions and H II region-like objects, we perform a systematic investigation of astronomical polycyclic aromatic hydrocarbon (PAH) features. Thirty-six objects were observed using the infrared camera on board the AKARI satellite as a part of a director's time program. In addition to the well known 3.3-3.6 mu m features, most spectra show a relatively weak emission feature at 5.22 mu m with sufficient signal-to-noise ratios, which we identify as the PAH 5.25 mu m band (previously reported). By careful analysis, we find good correlations between the 5.25 mu m band and both the aromatic hydrocarbon feature at 3.3 mu m and the aliphatic hydrocarbon features at around 3.4-3.6 mu m. The present results give us convincing evidence that the astronomical 5.25 mu m band is associated with C-H vibrations, as suggested by previous studies, and show its potential to probe the PAH size distribution. The analysis also shows that the aliphatic-to-aromatic ratio of I-3.4-3.6 mu m/ I-3.3 mu m decreases against the ratio of the 3.7 mu m continuum intensity to the 3.3 mu m band, I-cont, 3.7 mu m/ I-3.3 mu m, which is an indicator of the ionization fraction of PAHs. The midinfrared color of I-9 mu m/ I-18 mu m also declines steeply against the ratio of the hydrogen recombination line Bra at 4.05 mu m to the 3.3 mu m band, I-Br alpha / I-3.3 mu m. These facts indicate possible dust processing inside or at the boundary of ionized gas.

    DOI: 10.1088/0004-637X/784/1/53

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  • Difference in the spatial distribution between H2O and CO 2 ICES in M 82 found with AKARI 査読

    Mitsuyoshi Yamagishi, Hidehiro Kaneda, Daisuke Ishihara, Shinki Oyabu, Takashi Onaka, Takashi Shimonishi, Toyoaki Suzuki, Young Chol Minh

    Astrophysical Journal Letters   773 ( 2 )   1 - 5   2013年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    With AKARI, we obtain the spatially resolved near-infrared (NIR) (2.5-5.0 μm) spectra for the nearby starburst galaxy M 82. These spectra clearly show absorption features due to interstellar ices. Based on the spectra, we created the column density maps of H2O and CO2 ices. As a result, we find that the spatial distribution of H2O ice is significantly different from that of CO2 ice
    H2O ice is widely distributed, while CO2 ice is concentrated near the galactic center. Our result reveals for the first time variations in CO2/H 2O ice abundance ratio on a galactic scale, suggesting that an ice-forming interstellar environment changes within a galaxy. We discuss the cause of the spatial variations in the ice abundance ratio, utilizing spectral information on the hydrogen recombination Brα and Brβ lines and the polycyclic aromatic hydrocarbon 3.3 μm emission appearing in the AKARI NIR spectra. © 2013. The American Astronomical Society. All rights reserved.

    DOI: 10.1088/2041-8205/773/2/L37

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  • Akari infrared camera survey of the large magellanic cloud. II. the near-infrared spectroscopic catalog 査読

    Takashi Shimonishi, Takashi Onaka, Daisuke Kato, Itsuki Sakon, Yoshifusa Ita, Akiko Kawamura, Hidehiro Kaneda

    Astronomical Journal   145 ( 2 )   1 - 14   2013年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)  

    We performed a near-infrared spectroscopic survey toward an area of 10 deg2 of the Large Magellanic Cloud (LMC) with the infrared satellite AKARI. Observations were carried out as part of the AKARI Large-area Survey of the Large Magellanic Cloud (LSLMC). The slitless multi-object spectroscopic capability of the AKARI/IRC enabled us to obtain low-resolution (R 20) spectra in 2-5 μm for a large number of point sources in the LMC. As a result of the survey, we extracted about 2000 infrared spectra of point sources. The data are organized as a near-infrared spectroscopic catalog. The catalog includes various infrared objects such as young stellar objects (YSOs), asymptotic giant branch (AGB) stars, supergiants, and so on. It is shown that 97% of the catalog sources have corresponding photometric data in the wavelength range from 1.2 to 11 μm, and 67% of the sources also have photometric data up to 24 μm. The catalog allows us to investigate near-infrared spectral features of sources by comparison with their infrared spectral energy distributions. In addition, it is estimated that about 10% of the catalog sources are observed at more than two different epochs. This enables us to study a spectroscopic variability of sources by using the present catalog. Initial results of source classifications for the LSLMC samples are presented. We classified 659 LSLMC spectra based on their near-infrared spectral features by visual inspection. As a result, it is shown that the present catalog includes 7 YSOs, 160 C-rich AGBs, 8 C-rich AGB candidates, 85 O-rich AGBs, 122 blue and yellow supergiants, 150 red super giants, and 128 unclassified sources. Distributions of the classified sources on the color-color and color-magnitude diagrams are discussed in the text. Continuous wavelength coverage and high spectroscopic sensitivity in 2-5 μm can only be achieved by space observations. This is an unprecedented large-scale spectroscopic survey toward the LMC in the near-infrared. A large number of near-infrared spectral data provided by the survey possess scientific potential that can be applied to various studies. In this paper, we present the details of the spectroscopic survey and the catalog, and discuss its scientific applications. © 2013. The American Astronomical Society. All rights reserved..

    DOI: 10.1088/0004-6256/145/2/32

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  • Infrared Spectroscopy of YSOs in the Magellanic Clouds 査読

    Takashi Shimonishi, Takashi Onaka, Daisuke Kato, Itsuki Sakon, Yoshifusa Ita, Akiko Kawamura, Hidehiro Kaneda

    NEW TRENDS IN RADIO ASTRONOMY IN THE ALMA ERA: THE 30TH ANNIVERSARY OF NOBEYAMA RADIO OBSERVATORY   476   307 - 308   2013年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:ASTRONOMICAL SOC PACIFIC  

    For the last few years, it has been pioneer days for infrared spectroscopic studies of extragalactic young stellar objects (YSOs). A number of embedded YSOs are spectroscopically identified in the Magellanic Clouds with AKARI and Spitzer, and their near- to mid-infrared spectral features are investigated in detail. In this proceeding, we are going to present our current research on the infrared spectroscopic observations of ices and dust around embedded YSOs in the Magellanic Clouds with AKARI.

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  • AKARI INFRARED CAMERA SURVEY OF THE LARGE MAGELLANIC CLOUD. I. POINT-SOURCE CATALOG 査読

    Daisuke Kato, Yoshifusa Ita, Takashi Onaka, Toshihiko Tanabe, Takashi Shimonishi, Itsuki Sakon, Hidehiro Kaneda, Akiko Kawamura, Takehiko Wada, Fumihiko Usui, Bon-Chul Koo, Mikako Matsuura, Hidenori Takahashi

    ASTRONOMICAL JOURNAL   144 ( 6 )   1 - 18   2012年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IOP PUBLISHING LTD  

    We present a near-to mid-infrared point-source catalog of five photometric bands at 3.2, 7, 11, 15, and 24 mu m for a 10 deg(2) area of the Large Magellanic Cloud (LMC) obtained with the Infrared Camera on board the AKARI satellite. To cover the survey area the observations were carried out at three separate seasons from 2006 May to June, 2006 October to December, and 2007 March to July. The 10 sigma limiting magnitudes of the present survey are 17.9, 13.8, 12.4, 9.9, and 8.6 mag at 3.2, 7, 11, 15, and 24 mu m, respectively. The photometric accuracy is estimated to be about 0.1 mag at 3.2 mu m and 0.06-0.07 mag in the other bands. The position accuracy is 0 ''.3 at 3.2, 7, and 11 mu m and 1 ''.0 at 15 and 24 mu m. The sensitivities at 3.2, 7, and 24 mu m are roughly comparable to those of the Spitzer SAGE LMC point-source catalog, while the AKARI catalog provides the data at 11 and 15 mu m, covering the mid-infrared spectral range contiguously. Two types of catalog are provided: a Catalog and an Archive. The Archive contains all the detected sources, while the Catalog only includes the sources that have a counterpart in the Spitzer SAGE point-source catalog. The Archive contains about 650,000, 140,000, 97,000, 43,000, and 52,000 sources at 3.2, 7, 11, 15, and 24 mu m, respectively. Based on the catalog, we discuss the luminosity functions at each band, the color-color diagram, and the color-magnitude diagram using the 3.2, 7, and 11 mu m band data. Stars without circumstellar envelopes, dusty C-rich and O-rich stars, young stellar objects, and background galaxies are located at distinct regions in the diagrams, suggesting that the present catalog is useful for the classification of objects toward the LMC.

    DOI: 10.1088/0004-6256/144/6/179

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  • AKARI NEAR-INFRARED SPECTROSCOPIC SURVEY FOR CO2 IN 18 COMETS 査読

    Takafumi Ootsubo, Hideyo Kawakita, Saki Hamada, Hitomi Kobayashi, Mitsuru Yamaguchi, Fumihiko Usui, Takao Nakagawa, Munetaka Ueno, Masateru Ishiguro, Tomohiko Sekiguchi, Jun-ichi Watanabe, Itsuki Sakon, Takashi Shimonishi, Takashi Onaka

    ASTROPHYSICAL JOURNAL   752 ( 1 )   1 - 12   2012年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IOP PUBLISHING LTD  

    We conducted a spectroscopic survey of cometary volatiles with the Infrared Camera on board the Japanese infrared satellite AKARI in the wavelength range from 2.5 to 5 mu m. In our survey, 18 comets, including both the Oort cloud comets and the Jupiter-family comets, were observed in the period from 2008 June to 2010 January, most of which were observed at least twice. The prominent emission bands in the observed spectra are the fundamental vibrational bands of water (H2O) at 2.7 mu m and carbon dioxide (CO2) at 4.3 mu m. The fundamental vibrational band of carbon monoxide (CO) around 4.7 mu m and the broad emission feature, probably related to carbon-hydrogen-bearing molecules, can also be recognized around the 3.3-3.5-mu m region in some of the comets. With respect to H2O, gas production rate ratios of CO2 have been derived in 17 comets, except for the comet 29P/Schwassmann-Wachmann 1. Our data set provides the largest homogeneous database of CO2/H2O production rate ratios in comets obtained so far. The CO2/H2O production rate ratios are considered to reflect the composition of cometary ice when a comet is observed at a heliocentric distance within similar to 2.5 AU, since H2O ice fully sublimates there. The CO2/H2O ratio in cometary ice spans from several to similar to 30% among the comets observed at &lt;2.5 AU (13 out of the 17 comets). Alternatively, the ratio of CO/CO2 in the comets seems to be smaller than unity based on our observations, although we only obtain upper limits for CO in most of the comets.

    DOI: 10.1088/0004-637X/752/1/15

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  • Summary of Observations of the Infrared Camera (IRC) onboard AKARI 査読

    T. Onaka, H. Matsuhara, T. Wada, D. Ishihara, Y. Ohyama, I. Sakon, T. Shimonishi, R. Ohsawa, T. I. Mori, F. Egusa, F. Usui, S. Takita, H. Murakami, S. Oyabu, M. Yamagishi, T. Mori, A. Mouri, T. Kondo, S. Suzuki, H. Kaneda, Y. Ita, T. Ootsubo

    SPACE TELESCOPES AND INSTRUMENTATION 2012: OPTICAL, INFRARED, AND MILLIMETER WAVE   8442   2012年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:SPIE-INT SOC OPTICAL ENGINEERING  

    AKARI, the Japanese satellite mission dedicated to infrared astronomy was launched in 2006 February and exhausted its liquid helium in 2007 August. During the cold mission phase, the Infrared Camera (IRC) onboard carried out an all-sky survey at 9 and 18 mu m with better spatial resolution and higher sensitivity than IRAS. Both bands also have slightly shorter wavelength coverage than IRAS 12 and 25 mu m bands and thus provide different information on the infrared sky. All-sky image data of the IRC are now in the final processing and will be released to the public within a year. After the exhaustion of the cryogen, the telescope and focal plane instruments of AKARI had still been kept at sufficiently low temperatures owing to the onboard cryocooler. Near-infrared (NIR) imaging and spectroscopic observations with the IRC had continued until 2011 May, when the spacecraft had a serious problem in the power supply system that forced us to terminate the observation. The IRC carried out nearly 20000 pointing observations in total despite of its near-earth orbit. About a half of them were performed after the exhaustion of the cryogen in the spectroscopic modes, which provided high-sensitivity NIR spectra from 2 to 5 mu m without disturbance of the terrestrial atmosphere. During the warm mission phase, the temperature of the instrument gradually increased and changed the array operation conditions. We present a summary of AKARI/IRC observations, including the all-sky mid-infrared diffuse data as well as the data taken in the warm mission phase.

    DOI: 10.1117/12.926717

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  • AKARI NEAR-INFRARED SPECTROSCOPIC OBSERVATIONS OF INTERSTELLAR ICES IN THE EDGE-ON STARBURST GALAXY NGC 253 査読

    Mitsuyoshi Yamagishi, Hidehiro Kaneda, Daisuke Ishihara, Shinki Oyabu, Takashi Onaka, Takashi Shimonishi, Toyoaki Suzuki

    ASTROPHYSICAL JOURNAL LETTERS   731 ( 1 )   1 - 5   2011年4月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IOP PUBLISHING LTD  

    We present the spatially resolved near-infrared (2.5-5.0 mu m) spectra of the edge-on starburst galaxy NGC 253 obtained with the Infrared Camera on board AKARI. Near the center of the galaxy, we clearly detect the absorption features of interstellar ices (H2O: 3.05 mu m, CO2: 4.27 mu m, and XCN: 4.62 mu m) and the emission of polycyclic aromatic hydrocarbons (PAHs) at 3.29 mu m and the hydrogen recombination line Br alpha at 4.05 mu m. We find that the distributions of the ices differ from those of the PAH and gas. We calculate the column densities of the ices and derive the abundance ratios of N(CO2)/N(H2O) = 0.17 +/- 0.05. They are similar to those obtained around the massive young stellar objects in our Galaxy (0.17 +/- 0.03), although a much stronger interstellar radiation field and higher dust temperature are expected near the center of NGC 253.

    DOI: 10.1088/2041-8205/731/1/L20

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  • AKARI NEAR-INFRARED SPECTROSCOPY OF 3 MICRON PAH AND 4 MICRON PAD FEATURES 査読

    T. Onaka, I. Sakon, R. Ohsawa, T. Shimonishi, Y. Okada, M. Tanaka, H. Kaneda

    PAHS AND THE UNIVERSE: A SYMPOSIUM TO CELEBRATE THE 25TH ANNIVERSARY OF THE PAH HYPOTHESIS   46   55 - +   2011年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:E D P SCIENCES  

    Near-infrared (NIR; 2.5-5 mu m) low-resolution (lambda/Delta lambda similar to 100) spectra were obtained for a number of Galactic and extragalactic objects with the Infrared Camera (IRC) in the AKARI warm mission. These data provide us with the first opportunity to make a systematic study of the 3.3-3.5 mu m PAH features in a galactic scale as well as within an object. Whereas the 3.3 mu m band is well resolved in most spectra, the 3.5 mu m band is not clearly separated from the 3.4 mu m band in the IRC spectrum. The intensity ratio of the summation of the 3.4 and 3.5 mu m bands to the 3.3 mu m band shows a tendency to increase towards the Galactic center, although a large variation in the ratio is also seen in a local scale. A search for deuterated PAH features in the 4 mu m region is carried out in IRC NIR spectra. Emission lines originating from the ionized gas together with the detector anomaly hamper an accurate search at certain wavelengths, but little convincing evidence has so far been obtained for the presence of significant features in 4.2-4.7 mu m. A conservative upper limit of a few percents is obtained for the integrated intensity ratio of the 4.4-4.7 mu m possible features to the 3.3-3.5 mu m PAH features in the spectra so far obtained.

    DOI: 10.1051/eas/1146006

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  • Spectroscopic observations of ices around embedded young stellar objects in the Large Magellanic Cloud with AKARI 査読

    T. Shimonishi, T. Onaka, D. Kato, I. Sakon, Y. Ita, A. Kawamura, H. Kaneda

    ASTRONOMY & ASTROPHYSICS   514 ( A12 )   1 - 12   2010年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:EDP SCIENCES S A  

    Aims. The aim of this study is to understand the chemical conditions of ices around embedded young stellar objects (YSOs) in the metal-poor Large Magellanic Cloud (LMC).
    Methods. We performed near-infrared (2.5-5 mu m) spectroscopic observations toward 12 massive embedded YSOs and their candidates in the LMC using the infrared camera (IRC) onboard AKARI. We estimated the column densities of the H2O, CO2, and CO ices based on their 3.05, 4.27, and 4.67 mu m absorption features, and we investigated the correlation between ice abundances and physical properties of YSOs.
    Results. The ice absorption features of H2O, CO2, (CO2)-C-13, CO, CH3OH, and possibly XCN are detected in the spectra. In addition, hydrogen recombination lines and PAH emission bands are detected toward the majority of the targets. The derived typical CO2/H2O ice ratio of our samples (similar to 0.36 +/- 0.09) is greater than that of Galactic massive YSOs (similar to 0.17 +/- 0.03), while the CO/H2O ice ratio is comparable. It is shown that the CO2 ice abundance does not correlate with the observed characteristics of YSOs: the strength of hydrogen recombination line and the total luminosity. Likewise, clear correlation is not seen between the CO ice abundance and YSO characteristics, but it is suggested that the CO ice abundance of luminous samples is significantly lower than in other samples.
    Conclusions. The systematic difference in the CO2 ice abundance around the LMC's massive YSOs, which was suggested by previous studies, is confirmed with the new near-IR data. We suggest that the strong ultraviolet radiation field and/or the high dust temperature in the LMC are responsible for the observed high abundance of the CO2 ice. It is suggested that the internal stellar radiation does not play an important role in the evolution of the CO2 ice around a massive YSO, while more volatile molecules like CO are susceptible to the effect of the stellar radiation.

    DOI: 10.1051/0004-6361/200913815

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  • AKARI warm mission 査読

    Takashi Onaka, Hideo Matsuhara, Takehiko Wada, Daisuke Ishihara, Yoshifusa Ita, Youichi Ohyama, Takafumi Ootsubo, Shinki Oyabu, Itsuki Sakon, Takashi Shimonishi, Satoshi Takita, Tanabe Toshihiko, Fumihiko Usui, Hiroshi Murakami

    SPACE TELESCOPES AND INSTRUMENTATION 2010: OPTICAL, INFRARED, AND MILLIMETER WAVE   7731   2010年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:SPIE-INT SOC OPTICAL ENGINEERING  

    AKARI, the Japanese satellite mission dedicated for infrared astronomy launched in 2006 February, exhausted its 180 litter liquid helium (LHe) in 2007 August. After the LHe exhaustion, the telescope and focal plane of AKARI have still been kept less than 50K by the onboard cryocooler and near-infrared (NIR) observations with the Infrared Camera (IRC) are continuing. The data reduction software optimized for the warm mission enables us to carry out efficient and sensitive observations in the NIR despite the increase of hot pixels. In particular, the NIR spectroscopic capability of the IRC provides a unique opportunity to obtain spectra in 2.5-5 mu m with a high sensitivity, which will not be able to be carried out with any other facilities until JWST. An overview of the AKARI warm mission is given together with the performance and some observational results taken during the warm mission.

    DOI: 10.1117/12.856568

    Web of Science

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  • AKARI near-infrared spectroscopy: Detection of H2O and CO2 ices toward young stellar objects in the Large Magellanic Cloud 査読

    Takashi Shimonishi, Takashi Onaka, Daisuke Kato, Itsuki Sakon, Yoshifusa Ita, Akiko Kawamura, Hidehiro Kaneda

    MAGELLANIC SYSTEM: STARS, GAS, AND GALAXIES   686 ( 256 )   233 - +   2009年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:CAMBRIDGE UNIV PRESS  

    We present the first results of the AKARI Infrared Camera near-infrared spectroscopic survey of the Large Magellanic Cloud (LMC). The circumstellar material of young stellar objects (YSOs) are affected by galactic environments such as a metallicity or radiation field. Ices control the chemical balance of circumsellar environments of embedded YSOs. We detected absorption features of the H2O ice 3.05 mu m and the CO2 ice 4.27 mu m stretching mode toward seven massive YSOs in the LMC. This is the first detection of the 4.27 mu m CO2 ice confirmed to be YSOs. We used a curve-of-growth method to evaluate the column densities of the ices and derived the CO2/H2O ratio to be 0.45 +/- 0.17. This is clearly higher than that seen in Galactic massive YSOs (0.17 +/- 0.03). We suggest that the strong ultraviolet radiation field and/or the high dust temperature in the LMC may be responsible for the observed high CO2 ice abundance.

    DOI: 10.1017/S1743921308028494

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  • Ices around Extragalactic Young Stellar Objects 査読

    Takashi Shimonishi, Takashi Onaka, Daisuke Kato, Itsuki Sakon, Yoshifusa Ita, Akiko Kawamura, Hidehiro Kaneda

    AKARI, A LIGHT TO ILLUMINATE THE MISTY UNIVERSE   418   55 - +   2009年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:ASTRONOMICAL SOC PACIFIC  

    The infrared spectra of young stellar objects (YSOs) often show absorption features of ices. So far, almost all of the observations of ices around YSOs have been limited to Galactic objects. We here report the result of 2.5-5 mu m spectroscopy of YSOs in the Large Magellanic Cloud with infrared satellite AKARI. Absorption features of H2O, CO2 and CO ices are detected toward these extragalactic YSOs, and derived CO2/H2O ice ratio in the LMC shows a higher value than Galactic YSOs. In this paper, we discuss the different chemical conditions around extragalactic YSOs.

    Web of Science

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  • Near-infrared Spectroscopic Observation of Ices around Extragalactic Young Stellar Objects 査読

    Takashi Shimonishi, Takashi Onaka, Daisuke Kato, Itsuki Sakon, Yoshifusa Ita, Akiko Kawamura, Hidehiro Kaneda

    EXOPLANETS AND DISKS: THEIR FORMATION AND DIVERSITY   1158   155 - +   2009年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:AMER INST PHYSICS  

    We report the result of the 2-5 mu m spectroscopy of massive young stellar objects (YSOs) in the Large Magellanic Cloud (LMC) using the infrared satellite AKARI. Absorption features of H2O, CO2 and CO ices are detected toward these extragalactic YSOs, and derived CO2/H2O ratio in the LMC showed a higher value than galactic YSOs. In this proceeding, we discuss the difference of a chemical conditions around extragalactic YSOs.

    Web of Science

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  • AKARI IRC Survey of the Large Magellanic Cloud: Outline of the Survey and Initial Results 査読

    Yoshifusa Ita, Takashi Onaka, Daisuke Kato, Toshihiko Tanabe, Itsuki Sakon, Hidehiro Kaneda, Akiko Kawamura, Takashi Shimonishi, Takehiko Wada, Fumihiko Usui, Bon-Chul Koo, Mikako Matsuura, Hidenori Takahashi, Yoshikazu Nakada, Tetsuo Hasegawa, Motohide Tamura

    PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN   60   S435 - S451   2008年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:OXFORD UNIV PRESS  

    We observed an area of 10 deg(2) of the Large Magellanic Cloud using the Infrared Camera (IRC) on board AKARI. The observations were carried out using five imaging filters (3, 7, 11, 15, and 24 mu m) and a dispersion prism (2-5 mu m, lambda/Delta lambda similar to 20) equipped in the IRC. This paper describes an outline of our survey project, and presents some initial results using imaging data that detected over 5.9 x 10(5) near-infrared and 6.4 x 10(4) mid-infrared point sources. The 10 sigma detection limits of our survey are about 16.5, 14.0, 12.3, 10.8, and 9.2 in Vega-magnitude at 3, 7, 11, 15, and 24 mu m, respectively. The 11 and 15 Am data, which are unique to AKARI IRC, allow us to construct color-magnitude diagrams that are useful to identify stars with circumstellar dust. We found a new sequence in the color-magnitude diagram, which is attributed to red giants with luminosity fainter than that of the tip of the first red-giant branch. We suggest that this sequence is likely to be related to the broad emission feature of aluminum oxide at 11.5 mu m. The 11 and 15 mu m data also indicate that the ([11]-[15]) color of both oxygen-rich and carbon-rich red giants once becomes blue, and then turns red again in the course of their evolution, probably due to a change in the flux ratio of the silicate or silicon carbide emission feature at 10 or 11.3 mu m to the 15 mu m flux.

    DOI: 10.1093/pasj/60.sp2.S435

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  • AKARI NEAR-INFRARED SPECTROSCOPY: DETECTION OF H2O AND CO2 ICES TOWARD YOUNG STELLAR OBJECTS IN THE LARGE MAGELLANIC CLOUD 査読

    Takashi Shimonishi, Takashi Onaka, Daisuke Kato, Itsuki Sakon, Yoshifusa Ita, Akiko Kawamura, Hidehiro Kaneda

    ASTROPHYSICAL JOURNAL LETTERS   686 ( 2 )   L99 - L102   2008年10月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IOP PUBLISHING LTD  

    We present the first results of AKARI Infrared Camera near-infrared spectroscopic survey of the Large Magellanic Cloud (LMC). We detected absorption features of the H2O ice 3.05 mu m and the CO2 ice 4.27 mu m stretching mode toward seven massive young stellar objects (YSOs). These samples are for the first time spectroscopically confirmed to be YSOs. We used a curve-of-growth method to evaluate the column densities of the ices and derived the CO2/H2O ratio to be 0.45 +/- 0.17. This is clearly higher than that seen in Galactic massive YSOs (0.17 +/- 0.03). We suggest that the strong ultraviolet radiation field and/or the high dust temperature in the LMC may be responsible for the observed high CO2 ice abundance.

    Web of Science

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  • AKARI near-infrared spectroscopy: Detection of H2O and CO 2 ICES toward young stellar objects in the Large Magellanic Cloud 査読

    Takashi Shimonishi, Takashi Onaka, Daisuke Kato, Itsuki Sakon, Yoshifusa Ita, Akiko Kawamura, Hidehiro Kaneda

    Astrophysical Journal   686 ( 2 )   L99 - L102   2008年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:Institute of Physics Publishing  

    We present the first results of AKARI Infrared Camera near-infrared spectroscopic survey of the Large Magellanic Cloud (LMC). We detected absorption features of the H2O ice 3.05 μm and the CO2 ice 4.27 μm stretching mode toward seven massive young stellar objects (YSOs). These samples are for the first time spectroscopically confirmed to be YSOs. We used a curve-of-growth method to evaluate the column densities of the ices and derived the CO2/H2O ratio to be 0.45 ± 0.17. This is clearly higher than that seen in Galactic massive YSOs (0.17 ± 0.03). We suggest that the strong ultraviolet radiation field and/or the high dust temperature in the LMC may be responsible for the observed high CO2 ice abundance. © 2008. The American Astronomical Society. All rights reserved. Printed in U.S.A.

    DOI: 10.1086/592948

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▶ 全件表示

MISC

  • 「あかり」と地上望遠鏡の連携が明らかにする低重元素量銀河中の原始星の化学 招待

    下西隆

    ISASニュース   ( 470 )   1 - 3   2020年5月

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    担当区分:筆頭著者, 責任著者   記述言語:日本語   掲載種別:記事・総説・解説・論説等(大学・研究所紀要)  

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  • ALMA による銀河系外ホットコアの初検出 招待

    下西 隆

    天文月報   110 ( 6 )   386 - 392   2017年5月

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    記述言語:日本語   掲載種別:記事・総説・解説・論説等(その他)   出版者・発行元:日本天文学会  

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  • 第31回Grain Formation Workshop報告

    本田 充彦, 左近 樹, 木村 勇気, 三浦 均, 下西 隆, 瀧川 晶, 田中 今日子, 上塚 貴史

    日本惑星科学会誌遊星人   24 ( 1 )   60 - 62   2015年

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    記述言語:日本語   出版者・発行元:日本惑星科学会  

    CiNii Article

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講演・口頭発表等

  • Chemical Complexity of Star-Forming Regions at Low Metallicity 招待

    Takashi Shimonishi, Ankan Das, Nami Sakai, Kei Tanaka, Yuri Aikawa, Takashi Onaka, Yoshimasa Watanabe, Yuri Nishimura

    43rd COSPAR Scientific Assembly  2021年1月 

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    開催年月日: 2021年1月 - 2021年2月

    記述言語:英語   会議種別:口頭発表(招待・特別)  

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  • From Ice to Gas: Astrochemical perspective in the JWST era and the synergy with ALMA 招待

    Takashi Shimonishi

    ALMA/45m/ASTE Users Meeting FY2020  2021年1月 

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    開催年月日: 2021年1月

    記述言語:英語   会議種別:口頭発表(招待・特別)  

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  • アルマで探る銀河系最外縁部の星形成と星間物質の化学的多様性

    下西隆

    新学術領域「星惑星形成」2020年度大研究会  2020年9月 

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    開催年月日: 2020年9月 - 2020年10月

    会議種別:口頭発表(一般)  

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  • 星形成領域の星間氷観測

    下西隆

    第36回Grain Formation Workshop  2020年2月 

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    開催年月日: 2020年2月

    記述言語:日本語   会議種別:口頭発表(一般)  

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  • ALMA View of Chemistry of Hot Molecular Cores at Low Metallicity

    Takashi Shimonishi

    East-Asian ALMA Science Workshop 2019  2020年2月 

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    開催年月日: 2020年2月

    記述言語:英語   会議種別:口頭発表(一般)  

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  • Observations of low-metallicity hot cores with ALMA

    下西隆

    大質量形成ワークショップ2020 「大質量星形成研究の現状と次世代観測装置へ向けた展望」  2020年1月 

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    開催年月日: 2020年1月

    記述言語:日本語   会議種別:口頭発表(一般)  

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  • Astrochemistry at the Extreme Outer Galaxy

    Takashi Shimonishi

    Molecular gas observations toward the Local Group and the outer Milky Way  2020年1月 

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    開催年月日: 2020年1月

    記述言語:英語   会議種別:口頭発表(一般)  

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  • 星間氷に含まれるリンとその観測可能性

    下西隆

    第一回 リンと生命の起源研究会  2019年9月 

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    開催年月日: 2019年9月

    記述言語:日本語   会議種別:口頭発表(一般)  

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  • 多波長天文観測による宇宙分子進化史の研究 招待

    下西隆

    新潟薬科大学 薬学総合セミナー  2020年1月 

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    記述言語:日本語   会議種別:公開講演,セミナー,チュートリアル,講習,講義等  

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  • Physics and Chemistry of a Low-Metallicity Hot Molecular Core in the LMC

    下西 隆

    日本天文学会秋季年会  2019年9月 

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    記述言語:日本語   会議種別:口頭発表(一般)  

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  • NIR-MIR-Radio Spectroscopic Study of Astrochemistry at Low Metallicity 国際会議

    下西 隆

    Mid-infrared Astronomy – Past 20 years and Future 20 years  2019年8月 

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    記述言語:英語   会議種別:口頭発表(一般)  

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  • 広視野赤外観測による近傍星形成銀河内の原始星探査 招待

    下西 隆

    (近)赤外線広視野サイエンスワークショップ ~2020年代に我々はどう主導権を確保するか?~  2019年7月 

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    記述言語:日本語   会議種別:口頭発表(招待・特別)  

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  • Astrochemistry under low-metallicity conditions 招待

    下西 隆

    RIKEN r-EMU seminar  2019年5月 

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    記述言語:英語   会議種別:公開講演,セミナー,チュートリアル,講習,講義等  

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  • SPICA observations of interstellar chemistry at low metallicity 国際会議

    下西 隆

    Exploring the Infrared Universe: The Promise of SPICA  2019年5月 

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    記述言語:英語   会議種別:口頭発表(一般)  

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  • 赤外線天文観測で探る星間氷の諸性質 招待

    下西 隆

    日本物理学会 第74回年次大会  2019年3月 

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    記述言語:日本語   会議種別:口頭発表(招待・特別)  

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  • Observations of hot molecular cores in the Magellanic Clouds: Current status and future prospects 国際会議

    下西 隆

    Star formation with ALMA: Evolution from molecular clouds to protostars  2019年3月 

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    記述言語:英語   会議種別:口頭発表(一般)  

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  • 量子化学計算による氷ダスト表面での原子の吸着エネルギー推定と分子雲化学組成への影響の調査

    下西 隆

    第35回 Grain Formation Workshop  2019年2月 

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    記述言語:日本語   会議種別:口頭発表(一般)  

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  • Interstellar molecules at low metallicity explored through observations extragalactic star-forming regions 招待 国際会議

    下西 隆

    Exploring the Universe: Near Earth space science to extragalactic astronomy  2018年11月 

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    記述言語:英語   会議種別:口頭発表(基調)  

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  • Molecular complexity around a high-mass young stellar object in the Small Magellanic Cloud seen by ALMA

    下西 隆

    日本天文学会秋季年会  2018年9月 

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    記述言語:日本語   会議種別:口頭発表(一般)  

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  • 2030年代に期待する望遠鏡/装置3(星間物質) 招待

    下西 隆

    光赤天連シンポジウム2018  2018年9月 

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    記述言語:日本語   会議種別:口頭発表(招待・特別)  

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  • The detection of abundant cold methanol gas in the Small Magellanic Cloud 国際会議

    下西 隆

    IAU General Assembly Symposium 344 -Dwarf Galaxies: From the Deep Universe to the Present  2018年8月 

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    記述言語:英語   会議種別:ポスター発表  

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  • Organic molecules at 0.2 solar metallicity 国際会議

    下西 隆

    The 11th meeting on Cosmic Dust  2018年8月 

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    記述言語:英語   会議種別:口頭発表(一般)  

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  • The detection of abundant cold methanol gas at 0.2 solar metallicity 招待 国際会議

    下西 隆

    42nd COSPAR Scientific Assembly  2018年7月 

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    記述言語:英語   会議種別:口頭発表(招待・特別)  

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  • Astrochemical observations of low-metallicity star-forming regions 招待 国際会議

    下西 隆

    High Mass Star Formation Workshop 2018  2018年3月 

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    記述言語:英語   会議種別:口頭発表(招待・特別)  

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  • 第一原理計算による星間氷表面への原子の吸着エネルギーの推定 2: 分子雲化学組成への影響

    下西 隆

    日本天文学会春季年会  2018年3月 

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    記述言語:日本語   会議種別:口頭発表(一般)  

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  • マゼラン雲の観測で探る低金属量銀河の星間化学 招待

    下西 隆

    日本天文学会春季年会  2018年3月 

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    記述言語:日本語   会議種別:口頭発表(基調)  

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  • Chemical properties of low metallicity star-forming regions 招待 国際会議

    下西 隆

    The 4th AKARI International Conference  2017年10月 

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    記述言語:英語   会議種別:口頭発表(招待・特別)  

    開催地:日本国 Tokyo  

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  • Ices in star-forming regions: the role of metallicity 招待 国際会議

    下西 隆

    The 10th meeting on Cosmic Dust  2017年8月 

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    記述言語:英語   会議種別:口頭発表(招待・特別)  

    開催地:日本国 東京  

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  • 赤外線アストロケミストリーの展望 招待

    下西 隆

    光学赤外線天文連絡会シンポジウム 2017  2017年7月 

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    記述言語:日本語   会議種別:口頭発表(招待・特別)  

    開催地:日本国 東京  

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  • Observations of a hot molecular core in a low metallicity dwarf galaxy 国際会議

    下西 隆

    IAU Symposium 332, Astrochemistry VII -Through the Cosmos from Galaxies to Planets-  2017年3月 

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    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:チリ Puerto Varas  

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  • あかりが切り開く銀河系外アストロケミストリーの世界

    下西 隆

    「あかり」サイエンスワークショップ  2016年11月 

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    記述言語:日本語   会議種別:口頭発表(一般)  

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  • Observations of ices at low metallicity 招待 国際会議

    下西 隆

    Ice Age -The Era of the James Web Space Telescope-  2016年10月 

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    記述言語:英語   会議種別:口頭発表(招待・特別)  

    開催地:オランダ Leiden  

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  • First detection of an extragalactic hot molecular core with ALMA

    下西 隆

    日本天文学会秋季年会  2016年9月 

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    記述言語:日本語   会議種別:口頭発表(一般)  

    開催地:日本国 松山  

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  • Observations of a hot molecular core in a nearby low metallicity galaxy 国際会議

    下西 隆

    The 9th meeting on Cosmic Dust  2016年8月 

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    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:日本国 仙台  

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  • Observations of a hot molecular core in the Large Magellanic Cloud with ALMA 国際会議

    下西 隆

    Star Formation in Different Environments  2016年7月 

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    会議種別:ポスター発表  

    開催地:ベトナム Quy Nhon  

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  • 系外銀河における水・有機分子生成

    下西 隆

    宇宙生命計算科学連携拠点 第2回ワークショップ  2016年4月 

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    記述言語:日本語   会議種別:口頭発表(一般)  

    開催地:日本国 つくば  

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  • Observations of Water and Methanol Ices in the Large Magellanic Cloud 国際会議

    下西 隆

    Water in the Universe: From Clouds to Oceans  2016年4月 

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    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:オランダ Leiden  

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  • ALMA Observations of a Hot Molecular Core in the Large Magellanic Cloud 国際会議

    下西 隆

    Molecular Gas in Galactic Environments  2016年4月 

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    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:アメリカ合衆国 Charlottesville  

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  • VLT infrared spectroscopic observations of high-mass YSOs in the Large Magellanic Cloud

    下西 隆

    第32回Grain Formation Workshop  2015年12月 

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    記述言語:日本語   会議種別:口頭発表(一般)  

    開催地:日本国 札幌  

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  • Infrared spectroscopy of embedded high-mass YSOs in the Large Magellanic Cloud: Methanol and the 3.47 mm band 国際会議

    下西 隆

    From Interstellar Ices to Polycyclic Aromatic Hydrocarbons  2015年9月 

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    記述言語:日本語   会議種別:口頭発表(一般)  

    開催地:アメリカ合衆国 Annapolis  

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  • Infrared spectroscopy in the C--H stretching region towards embedded high-mass young stellar objects in the Large Magellanic Cloud

    下西 隆

    日本天文学会秋季年会  2015年9月 

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    記述言語:日本語   会議種別:口頭発表(一般)  

    開催地:日本国 兵庫  

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  • Infrared spectroscopy in the C--H stretching region towards embedded high-mass young stellar objects in the Large Magellanic Cloud 国際会議

    下西 隆

    The 8th meeting on Cosmic Dust  2015年8月 

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    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:日本国 東京  

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  • AKARI Infrared Camera Survey of the Large Magellanic Cloud 国際会議

    下西 隆

    国際天文学連合総会  2015年8月 

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    記述言語:英語   会議種別:ポスター発表  

    開催地:アメリカ合衆国 Honolulu  

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  • Infrared spectroscopy in the C--H stretching region towards embedded high-mass young stellar objects in the Large Magellanic Cloud 国際会議

    下西 隆

    国際天文学連合総会  2015年8月 

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    記述言語:英語   会議種別:ポスター発表  

    開催地:アメリカ合衆国 Honolulu  

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  • Infrared spectroscopy of solid methanol around embedded high-mass YSOs in the LMC

    下西 隆

    High-mass star-formation workshop  2015年7月 

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    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:日本国 東京  

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  • Processing of ices in a massive star-forming region

    下西 隆

    第31回 Grain Formation Workshop  2015年1月 

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    記述言語:英語   会議種別:口頭発表(一般)  

    開催地:日本国 神奈川  

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  • Molecular cloud chemistry in low metallicity environments - the case of the LMC- 国際会議

    下西 隆

    International Conference on Interstellar Dust, Molecules and Chemistry  2014年12月 

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    記述言語:英語   会議種別:口頭発表(一般)  

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  • Processing of ices in a massive star-forming region 国際会議

    下西 隆

    Workshop on Interstellar Matter 2014  2014年10月 

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    記述言語:英語   会議種別:ポスター発表  

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  • Spatial Distribution of Ices in a High-mass Star-forming Region 国際会議

    下西 隆

    The 7th meeting on Cosmic Dust  2014年8月 

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    記述言語:英語   会議種別:口頭発表(一般)  

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  • A multiwavelength spectroscopic study of molecular chemistry in the Large Magellanic Cloud 国際会議

    下西 隆

    THE UNIVERSE IN THE LIGHT OF AKARI and Synergy with future Large Space Telescopes  2014年7月 

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    記述言語:英語   会議種別:口頭発表(一般)  

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  • 大マゼラン雲の分子雲に対する3 mm帯スペクトルラインサーベイ 1. 高密度ガス探査

    下西 隆

    日本天文学会春季年会  2014年3月 

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    記述言語:日本語   会議種別:口頭発表(一般)  

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  • 分子雲の化学進化計算に基づく銀河の環境的要因が氷ダストの化学組成に与える影響の調査

    下西 隆

    日本天文学会秋季年会  2013年9月 

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    記述言語:日本語   会議種別:口頭発表(一般)  

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  • Infrared Observations of Methanol Ice in the Large Magellanic Cloud 国際会議

    下西 隆

    The 6th meeting on Cosmic Dust  2013年8月 

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    記述言語:英語   会議種別:口頭発表(一般)  

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  • 赤外線観測に基づくマゼラン雲内の原始星の研究 国際会議

    下西 隆

    ワークショップ「系外銀河の星間化学」  2013年6月 

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    記述言語:英語   会議種別:口頭発表(一般)  

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  • あかり大マセラン雲赤外線点源カタログ II. 分光カタログ

    下西 隆

    日本天文学会春季年会  2013年3月 

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    記述言語:日本語   会議種別:口頭発表(一般)  

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  • Ice Chemistry in the Magellanic Clouds 招待 国際会議

    下西 隆

    Workshop on Interstellar Matter 2012  2012年10月 

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    記述言語:英語   会議種別:口頭発表(招待・特別)  

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  • AKARI Near-infrared Spectroscopic Survey of the Large Magellanic Cloud 国際会議

    下西 隆

    The Magellanic System: In Perspective  2012年9月 

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    記述言語:英語   会議種別:口頭発表(一般)  

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  • AKARI Near-infrared Spectroscopic Catalog of the Large Magellanic Cloud 国際会議

    下西 隆

    COSPAR 2012  2012年7月 

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    記述言語:英語   会議種別:口頭発表(一般)  

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  • Infrared Study of Ices around Young Stellar Objects in the Magellanic Clouds 国際会議

    下西 隆

    The Second AKARI Conference, Legacy of AKARI: A Panoramic View of the Dusty Universe  2012年2月 

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    記述言語:英語   会議種別:口頭発表(一般)  

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  • Infrared Observations of Young Stellar Objects outside the Milky Way 国際会議

    下西 隆

    International Conference on Interstellar Dust, Molecules and Chemistry  2011年11月 

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    記述言語:英語   会議種別:口頭発表(一般)  

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  • あかりによる大マゼラン雲の点源近赤外分光サーベイ

    下西 隆

    日本天文学会秋季年会  2011年9月 

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    記述言語:日本語   会議種別:口頭発表(一般)  

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  • Effect of Galactic Environment on the Properties of Ices Around Embedded Young Stellar Objects 国際会議

    下西 隆

    Asia Oceania Geosciences Society 2011  2011年8月 

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    記述言語:英語   会議種別:口頭発表(一般)  

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  • Infrared Observations of Ices around YSOs in the Large and Small Magellanic Cloud 国際会議

    下西 隆

    Workshop of Interstellar Matter 2010  2010年9月 

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    記述言語:英語   会議種別:口頭発表(一般)  

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  • あかり衛星を用いた小マゼラン雲内の若い天体の周囲に存在する氷の近赤外分光観測

    下西 隆

    日本天文学会秋季年会  2010年9月 

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    記述言語:日本語   会議種別:口頭発表(一般)  

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  • Temporal Variations of Near-Infrared Spectra of Carbons Stars in the LMC 国際会議

    下西 隆

    Why Galaxies Care About AGB Stars II  2010年8月 

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    記述言語:英語   会議種別:口頭発表(一般)  

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  • Observations of ices around extragalactic young stellar objects by AKARI 招待 国際会議

    下西 隆

    Asia Oceania Geosciences Society 2010  2010年7月 

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    記述言語:英語   会議種別:口頭発表(招待・特別)  

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  • あかりで探るdustyな炭素星の近赤外スペクトルの時間変動

    下西 隆

    スペース赤外線観測による晩期型星研究の現状と将来  2009年12月 

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    記述言語:日本語   会議種別:口頭発表(一般)  

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  • Observational Study of Ices around Extragalactic YSOs with AKARI 国際会議

    下西 隆

    International Workshop on Interstellar Matter and Star Formation  2009年10月 

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    記述言語:英語   会議種別:口頭発表(一般)  

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  • 「あかり」で探る大マゼラン雲内の炭素星の2-5μmスペクトルに見られる変光の性質

    下西 隆

    日本天文学会秋季年会  2009年9月 

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    記述言語:日本語   会議種別:口頭発表(一般)  

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  • Ices around Extragalactic Young Stellar Objects 国際会議

    下西 隆

    42nd International Union of Pure and Applied Chemistry Congress  2009年8月 

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    記述言語:英語   会議種別:口頭発表(一般)  

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  • 2-5 μm Spectroscopic Observations of Ices around Extragalactic Young Stellar Objetcs 国際会議

    下西 隆

    AKARI 1st International Conference: a light to illuminate the misty Universe  2009年2月 

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    記述言語:英語   会議種別:口頭発表(一般)  

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  • AKARI Near-Infrared Spectroscopy of Young Stellar Objects in the LMC: Detection of H2O and CO2 ices 国際会議

    下西 隆

    IAU Symposium No.256, “The Magellanic System: Stars, Gas, and Galaxies”  2008年8月 

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    記述言語:英語   会議種別:口頭発表(一般)  

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  • AKARI Spectroscopy of YSOs in the Large Magellanic Cloud 国際会議

    下西 隆

    AKARI Workshop on Nearby Galaxies, ISM and Stars  2008年3月 

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    記述言語:英語   会議種別:口頭発表(一般)  

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  • AKARI NIR Spectroscopic Survey of the Large Magellanic Cloud -Detection of H2O and CO2 Ice feature-

    下西 隆

    日本天文学会春季年会  2008年3月 

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    記述言語:日本語   会議種別:口頭発表(一般)  

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  • あかり衛星による大マゼラン雲サーベイの初期解析結果 ~銀河系外YSO近赤外スペクトル探査の試み~

    下西 隆

    日本天文学会秋季年会  2007年9月 

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    記述言語:日本語   会議種別:口頭発表(一般)  

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  • あかりIRCによるLMC内のHerbigAe/Be型星近赤外分光観測の展望

    下西 隆, 尾中敬

    スペースからの赤外線観測による最新の天文学  2007年3月 

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    記述言語:日本語   会議種別:口頭発表(一般)  

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受賞

  • 第12回宇宙科学奨励賞

    2020年3月   宇宙科学振興会  

    下西隆

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  • Young Chemist Award

    2009年8月   42nd IUPAC Congress  

    Takashi Shimonishi

     詳細を見る

  • Student Award

    2008年8月   IAU Symposium No.256  

    Takashi Shimonishi

     詳細を見る

共同研究・競争的資金等の研究

  • 星間分子研究の新展開: 低金属量環境への拡張

    研究課題/領域番号:21H01145  2021年4月 - 2024年3月

    日本学術振興会  科学研究費助成事業 基盤研究(B)  基盤研究(B)

    下西 隆

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    担当区分:研究代表者 

    配分額:16770000円 ( 直接経費:12900000円 、 間接経費:3870000円 )

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  • 観測と星間化学モデルで迫る銀河系外縁部の化学的多様性形成史

    研究課題/領域番号:21H00037  2021年4月 - 2023年3月

    日本学術振興会  科学研究費助成事業 新学術領域研究(研究領域提案型)  新学術領域研究(研究領域提案型)

    下西 隆

      詳細を見る

    担当区分:研究代表者 

    配分額:2600000円 ( 直接経費:2000000円 、 間接経費:600000円 )

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  • 計算化学と電波観測の融合によるホットコア化学の研究

    2020年7月 - 2022年4月

    文部科学省  二国間交流事業 (インドDSTとの共同研究)  二国間交流事業 共同研究

    下西隆

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    担当区分:研究代表者 

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  • 電波および赤外線観測で切り拓く銀河系外縁部の星間化学

    2019年4月 - 2020年3月

    文部科学省  新学術領域研究(研究領域提案型・公募) 

    下西 隆

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    担当区分:研究代表者  資金種別:競争的資金

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  • 高感度・高分解能観測で探る惑星系形成領域の化学進化

    研究課題/領域番号:20H05845  2020年11月 - 2025年3月

    日本学術振興会  科学研究費助成事業 学術変革領域研究(A)  学術変革領域研究(A)

    坂井 南美, 大屋 瑶子, 廣田 朋也, 酒井 剛, 渡邉 祥正, 山本 智, 下西 隆

      詳細を見る

    担当区分:研究分担者 

    配分額:136760000円 ( 直接経費:105200000円 、 間接経費:31560000円 )

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  • 多波長天文観測に基づく低重元素量環境下での星間分子化学の研究

    2015年4月 - 2018年3月

    文部科学省  科学研究費補助金(若手B) 

    下西 隆

      詳細を見る

    担当区分:研究代表者  資金種別:競争的資金

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  • 異なる金属量環境下における原始星の星周物質の化学的多様性の研究

    2012年4月 - 2014年12月

    文部科学省  科学研究費補助金(特別研究員奨励費PD) 

    下西 隆

      詳細を見る

    担当区分:研究代表者  資金種別:競争的資金

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  • 銀河系外の若い天体及びその周囲に存在する氷の観測的研究

    2010年4月 - 2012年3月

    文部科学省  科学研究費補助金(特別研究員奨励費DC2) 

    下西 隆

      詳細を見る

    担当区分:研究代表者  資金種別:競争的資金

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その他研究活動

  • 公益財団法人インテリジェントコスモス学術振興財団からの国際学会開催助成(宇宙塵に関する国際研究会"The 9th meeting on Cosmic Dust"の開催支援のため)。

    2016年8月

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担当経験のある授業科目(researchmap)

  • 数理演習

    2020年12月
    -
    現在
    機関名:新潟大学

     詳細を見る

  • 自然科学総論

    2020年10月
    -
    現在
    機関名:新潟大学

     詳細を見る

  • 基礎ゼミ「Interdisciplinary Sciences ~分野を飛び越えて大学での学びを広げよう~」

    2019年
    機関名:東北大学

     詳細を見る

  • 数理統計学演習

    2017年
    -
    2019年
    機関名:東北大学

     詳細を見る

  • 基礎ゼミ「君が天文学者になるセメスター」

    2016年
    -
    2017年
    機関名:東北大学

     詳細を見る

  • 天文学セミナー

    2015年
    -
    2018年
    機関名:東北大学

     詳細を見る

▶ 全件表示

担当経験のある授業科目

  • 自然環境科学総論

    2021年
    -
    現在
    機関名:新潟大学

  • 数理演習

    2020年
    -
    現在
    機関名:新潟大学