彗星核に含まれる塵の熱履歴と分子の同位体濃集から探る原始太陽系円盤の物理化学

• Project/Area Number: 15J10864
• Research Category: Grant-in-Aid for JSPS Fellows
• Allocation Type: Single-year Grants
• Section: 国内
• Research Field: Astronomy
• Research Institution: National Astronomical Observatory of Japan
• Principal Investigator: 新中 善晴 国立天文台, 天文情報センター, 特別研究員(PD)
• Project Period (FY): 2015-04-24 – 2018-03-31
• Project Status: Completed (Fiscal Year 2017)
• Budget Amount: ¥5,200,000 (Direct Cost: ¥4,000,000、Indirect Cost: ¥1,200,000); Fiscal Year 2017: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000); Fiscal Year 2016: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000); Fiscal Year 2015: ¥1,820,000 (Direct Cost: ¥1,400,000、Indirect Cost: ¥420,000)
• Keywords: 彗星 / 窒素同位体比 / 超小型深宇宙探査機 / オルソ／パラ存在量比 / 同位体比

Outline of Annual Research Achievements

近年、窒素原子の同位体の存在量比 (14N/15N比)が分子雲や原始惑星系円盤における化学進化という観点から注目されている。彗星のCN分子に関しては、従来紫外線波長域に見られるB-Xバンドが多く観測されてきた。しかし、同バンドは紫外線波長域に近いため、大気吸収による減光の影響を受けやすい。そのため、太陽に接近することで明るくなる彗星においては観測条件が悪いことが多い。また、彗星コマ中での彗星ダストによる減光の影響もあり、S/N比の良いスペクトルを得るのに不利となる。そこで本研究では、2013年11月に京都産業大学神山天文台に設置されていた近赤外線高分散分光器 WINERED で取得したC/2013 R1 (Lovejoy) 彗星の近赤外線スペクトルを用いて、これらの減光の影響が少ない近赤外線域に見られるCN分子のA-Xバンドを用いる方法を確立した。その結果、純粋な蛍光平衡状態だけではなく、分子間衝突等による励起の影響も考慮することで、観測スペクトルの再現に成功した。同位体比の導出については、S/Nが足りず上限値のみ決定できたが、先行研究で得られている値と矛盾しない結果となっている。また、初年度に滞在したベルギーのリエージュ大学のグループと協力し、2017年4月に急増光を示した C/2015 ER61彗星について、VLT望遠鏡で可視光高分散分光観測を実施した。得られたスペクトルからアンモニア分子の窒素同位体比を決定し、我々がこれまでに得ている彗星の値と同程度の値を示すことを明らかにした。一方で、OH分子のD同位体であるODは検出できなかったため、当初予定していた水分子のD/Hのサンプルを増やすことができず、彗星分子の同位体比とダストの組成比について統計的な議論はできていないことから、彗星に含まれる物質の形成環境を明らかにするにあたっての今後の課題である。

Research Progress Status

29年度が最終年度であるため、記入しない。

Strategy for Future Research Activity

29年度が最終年度であるため、記入しない。

Research Products

• [Journal Article] Isotopic ratios in outbursting comet C/2015 ER61 (2018)
  • Author(s): Yang Bin、Hutsemekers Damien、Shinnaka Yoshiharu、Opitom Cyrielle、Manfroid Jean、Jehin Emmanuel、Meech Karen J.、Hainaut Olivier R.、Keane Jacqueline V.、Gillon Michael
  • Journal Title: Astronomy and Astrophysics Volume: 609 Pages: L4-L4
  • DOI: 10.1051/0004-6361/201732100
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Near-infrared Spectroscopic Observations of Comet C/2013 R1 (Lovejoy) by WINERED: CN Red-system Band Emission (2017)
  • Author(s): Shinnaka Yoshiharu、Kawakita Hideyo、Kondo Sohei、Ikeda Yuji、Kobayashi Naoto、Hamano Satoshi、Sameshima Hiroaki、Fukue Kei、Matsunaga Noriyuki、Yasui Chikako、Izumi Natsuko、Mizumoto Misaki、Otsubo Shogo、Takenaka Keiichi、Watase Ayaka、Kawanishi Takafumi、Nakanishi Kenshi、Nakaoka Tetsuya
  • Journal Title: The Astronomical Journal Volume: 154 Issue: 2 Pages: 45-45
  • DOI: 10.3847/1538-3881/aa7576
  • Peer Reviewed
• [Journal Article] Imaging observations of the hydrogen coma of comet 67P/Churyumov-Gerasimenko in September 2015 by the PROCYON/LAICA (2017)
  • Author(s): Shinnaka, Y., N. Fougere, H. Kawakita, S. Kameda, M. R. Combi, S. Ikezawa, A. Seki, M. Kuwabara, M. Sato, M. Taguchi, I. Yoshikawa
  • Journal Title: Astronomical Journal Volume: 153 Issue: 2 Pages: 76-81
  • DOI: 10.3847/1538-3881/153/2/76
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Nitrogen isotopic ratio of cometary ammonia from high-resolution optical spectroscopic observations of C/2014 Q2 (Lovejoy) (2016)
  • Author(s): Y. Shinnaka, H. Kawakita
  • Journal Title: The Astronomical Journal Volume: 152 Issue: 5 Pages: 145-145
  • DOI: 10.3847/0004-6256/152/5/145
  • Peer Reviewed / Acknowledgement Compliant
• [Journal Article] Ortho-to-para abundance ratios of NH2 in 26 comets: implications for the real meaning of OPRs (2016)
  • Author(s): Y. Shinnaka, H. Kawakita, E. Jehin, A. Decock, D. Hutsemekers, J. Manfroid
  • Journal Title: Monthly Notices of the Royal Astronomical Society Volume: 462 Issue: Suppl 1 Pages: S124-S131
  • DOI: 10.1093/mnras/stw2298
  • Peer Reviewed / Open Access / Int'l Joint Research / Acknowledgement Compliant
• [Journal Article] Nitrogen isotopic ratios of NH2 in comets: implication for 15N-fractionation in cometary ammonia、Monthly Notices of the Royal Astronomical Society (2016)
  • Author(s): Y. Shinnaka, H. Kawakita, E. Jehin, A. Decock, D. Hutsemekers, J. Manfroid, A. Arai
  • Journal Title: Monthly Notices of the Royal Astronomical Society Volume: 462 Issue: Suppl 1 Pages: S195-S209
  • DOI: 10.1093/mnras/stw2410
  • Peer Reviewed / Open Access / Int'l Joint Research / Acknowledgement Compliant
• [Presentation] Preliminary results of imaging polarimetry of active asteroid (3200) Phaethon (2018)
  • Author(s): 新中善晴
  • Organizer: PERC Int'l Symposium on Dust & Parent Bodies
  • Int'l Joint Research
• [Presentation] 小惑星(3200) Phaethonの偏光撮像観測 (2018)
  • Author(s): 新中善晴
  • Organizer: 日本天文学会2018年春季年会
• [Presentation] 超小型深宇宙探査機PROCYONに搭載されたLAICA望遠鏡による67P/Churyumov-Gerasimenko彗星の水分子の生成率 (2017)
  • Author(s): Y. Shinnaka
  • Organizer: 日本天文学会2017年春季年会
  • Place of Presentation: 九州大学伊都キャンパス (福岡県福岡市)
  • Year and Date: 2017-03-14
• [Presentation] Ortho-to-Para Abundance Ratios (OPRs) of NH2 in Comets: The Meaning of OPRs of Cometary Volatiles (2017)
  • Author(s): Y. Shinnaka
  • Organizer: Subaru Users’ Meeting 2016
  • Place of Presentation: 国立天文台三鷹キャンパス (東京都三鷹市)
  • Year and Date: 2017-01-10
  • Int'l Joint Research
• [Presentation] Nitrogen isotopic ratios of NH2 and CN in comet C/2013 US10 (Catalina) based on high-resolution optical spectra taken by the HDS/Subaru (2017)
  • Author(s): Y. Shinnaka
  • Organizer: Subaru Users’ Meeting 2016
  • Place of Presentation: 国立天文台三鷹キャンパス (東京都三鷹市)
  • Year and Date: 2017-01-10
  • Int'l Joint Research
• [Presentation] Lyman αimagings of comet 67P/Churyumov-Gerasimenko by the PROCYON/LAICA (2017)
  • Author(s): 新中善晴
  • Organizer: JpGU-AUG Joint Meeting 2017
  • Int'l Joint Research
• [Presentation] 超小型深宇宙探査機PROCYONによるチュリュモフ・ゲラシメンコ彗星の水分子の生成率の決定 (2017)
  • Author(s): 新中善晴
  • Organizer: 第４７回彗星会議 旭川
• [Presentation] 17P/Holmes彗星の中間赤外線分光観測による鉱物組成比 (2017)
  • Author(s): 新中善晴
  • Organizer: 日本天文学会2017年秋季年会
• [Presentation] Mineral abundances of comet 17P/Holmes derived from the mid-infrared spectrum (2017)
  • Author(s): 新中善晴
  • Organizer: 49th Annual Division for Planetary Science Meeting
  • Int'l Joint Research
• [Presentation] Spectroscopic observations of 14N/15N ratios in both NH2 and CN in comet C/2013 US10 (Catalina) (2016)
  • Author(s): Y. Shinnaka
  • Organizer: DPS 48/EPSC 11 Meeting
  • Place of Presentation: Pasadena, CA, USA
  • Year and Date: 2016-10-16
  • Int'l Joint Research
• [Presentation] Survey for Ortho-to-Para Abundance Ratios (OPRs) of NH2 in Comets: Revisit to the Meaning of OPRs of Cometary Volatiles (2016)
  • Author(s): Y. Shinnaka
  • Organizer: DPS 48/EPSC 11 Meeting
  • Place of Presentation: Pasadena, CA, USA
  • Year and Date: 2016-10-16
  • Int'l Joint Research
• [Presentation] Lyman-alpha imaging of whole coma for 67P/Churyumov-Gerasimenko by PROCYON/LAICA (2016)
  • Author(s): Y. Shinnaka
  • Organizer: Cometary Science After Rosetta: Future Directions
  • Place of Presentation: UCL, London, UK
  • Year and Date: 2016-06-16
  • Int'l Joint Research
• [Presentation] Imaging Observations of Hydrogen Coma of Comet 67P/Churyumov-Gerasimenko by PROCYON/LAICA (2016)
  • Author(s): Yoshiharu Shinnaka
  • Organizer: Cometary Science after Rosetta: Future Directions
  • Place of Presentation: UCL/Birkbeck, London, UK
  • Year and Date: 2016-06-16
  • Int'l Joint Research
• [Presentation] Imaging Observations of Hydrogen Coma of 67P/Churyumov-Gerasimenko by PROCYON/LAICA (2016)
  • Author(s): Y. Shinnaka
  • Organizer: Cometary science after Rosetta
  • Place of Presentation: The Royal Society, London, UK
  • Year and Date: 2016-06-14
  • Int'l Joint Research
• [Presentation] Ortho-to-Para Abundance Ratios of water from high-resolution spectra of water ion in the optical wavelength region (2016)
  • Author(s): Y. Shinnaka
  • Organizer: Water in the universe: from clouds to oceans
  • Place of Presentation: ESA/ESTEC, Noordwijk, The Netherlands
  • Year and Date: 2016-04-12
  • Int'l Joint Research
• [Presentation] Ortho-to-Para Abundance Ratios of Water from High-Resolution Optical Spectra of Water Ion (2016)
  • Author(s): Yoshiharu Shinnaka
  • Organizer: Water in the Universe: From Clouds to Oceans
  • Place of Presentation: ESA/ESTEC, Noordwijk, The Netherlands
  • Year and Date: 2016-04-12
  • Int'l Joint Research
• [Presentation] Survey for nitrogen isotopic ratio of NH2 in comets: Implication for 15N-fractionation in cometary ammonia (2016)
  • Author(s): Yoshiharu Shinnaka
  • Organizer: from Giotto to Rosetta (50th ESLAB Symposium)
  • Place of Presentation: Leiden, The Netherlands
  • Year and Date: 2016-03-14
  • Int'l Joint Research
• [Presentation] Survey for Ortho-to-Para Abundance Ratios (OPRs) of Ammonia in 20 Comets (2016)
  • Author(s): Hideyo Kawakita
  • Organizer: from Giotto to Rosetta (50th ESLAB Symposium)
  • Place of Presentation: Leiden, The Netherlands
  • Year and Date: 2016-03-14
  • Int'l Joint Research
• [Presentation] Nitrogen Isotopic Ratios in Cometary NH2: Implication for 15N-fractionation in Ammonia (2015)
  • Author(s): Yoshiharu Shinnaka
  • Organizer: 47th Annual Meeting of Division for Planetary Science (DPS)
  • Place of Presentation: National Harbor, MD, USA
  • Year and Date: 2015-11-08
  • Int'l Joint Research
• [Remarks] 超小型探査機が彗星の水のなぞを解明
  • URL: http://www.nao.ac.jp/news/science/2017/20170124-procyon.html