世界初の近赤外線による重力マイクロレンズ法を用いた系外惑星探査

• Project/Area Number: 17J02146
• Research Category: Grant-in-Aid for JSPS Fellows
• Allocation Type: Single-year Grants
• Section: 国内
• Research Field: Astronomy
• Research Institution: Osaka University
• Principal Investigator: 平尾 優樹 大阪大学, 理学研究科, 特別研究員(DC1)
• Project Period (FY): 2017-04-26 – 2020-03-31
• Project Status: Completed (Fiscal Year 2019)
• Budget Amount: ¥2,500,000 (Direct Cost: ¥2,500,000); Fiscal Year 2019: ¥800,000 (Direct Cost: ¥800,000); Fiscal Year 2018: ¥800,000 (Direct Cost: ¥800,000); Fiscal Year 2017: ¥900,000 (Direct Cost: ¥900,000)
• Keywords: 重力マイクロレンズ / 系外惑星 / 近赤外線

Outline of Annual Research Achievements

昨年に引き続きPRIME（PRime-focus Infrared Microlensing Experiment）望遠鏡用近赤外線広視野カメラを製作するために、米国NASA/Goddard Space Flight Centerに滞在し、現地の研究者と共同でカメラの開発を行った。今年度は本番カメラの最終設計、およびテスト用のデュワーを用いた冷凍機を使った冷却試験を行った。検出器の読み出しにはNASAが開発したRoman宇宙望遠鏡（旧WFIRST衛星）にも使われるACADIA/MACIEシステムを使用することが決まった。今後、温度コントロールやフィルターホイールを動かすモーター制御などのシステムの構築を進め、本番カメラを完成させる。そして、南アフリカに建設中のPRIME望遠鏡に取り付け、動作確認などを行なった後、2021年度の初観測を目指す。その後、近赤外線による重力マイクロレンズのサーベイ観測を行い、銀河系中心部で新たな惑星を発見し、惑星形成過程に制限を与える。
惑星イベントOGLE-2017-BLG-0406の解析では、Gaia衛星によって新たに得られたイベントの固有速度が、これまでの結果と矛盾することがわかった。しかし、OGLEグループのデータを使うことで、これは非常に系統誤差が大きいことがわかった。新しい銀河系のモデルを使うことで惑星系の物理量を求めたところ、太陽系から5.2kpcの位置にある、0.56太陽質量の主星の周りを0.4木星質量の惑星が周る系であることがわかった。さらに、系の速度を求め、その距離と速度を銀河系のモデルと比較することで、ディスク成分の星である可能性が高いことを示した。2025年以降にKeckやELTといった大型望遠鏡やHSTやJWSTなどの宇宙望遠鏡で、高解像度の追観測を行うことで、惑星系を検出し、より詳細な系の物理量を求めることが期待される。

Research Progress Status

令和元年度が最終年度であるため、記入しない。

Strategy for Future Research Activity

令和元年度が最終年度であるため、記入しない。

Research Products

• [Int'l Joint Research] NASA / Goddard Space Flight Center(米国)
• [Int'l Joint Research] Massey University/Auckland University/Mt.John University Observatory(ニュージーランド)
• [Int'l Joint Research] Warsaw University Observatory(ポーランド)
• [Int'l Joint Research] NASA / Goddard Space Flight Center/Ohio State University(米国)
• [Int'l Joint Research] Massey University/University of Auckland/Mt. John University Observatory(ニュージーランド)
• [Int'l Joint Research] Warsaw University Observatory(ポーランド)
• [Journal Article] OGLE-2013-BLG-0911Lb: A Secondary on the Brown-dwarf Planet Boundary around an M Dwarf (2020)
  • Author(s): Miyazaki Shota、et al.
  • Journal Title: The Astronomical Journal Volume: 159 Issue: 2 Pages: 76-76
  • DOI: 10.3847/1538-3881/ab64de
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] OGLE-2015-BLG-1670Lb: A Cold Neptune beyond the Snow Line in the Provisional WFIRST Microlensing Survey Field (2019)
  • Author(s): Ranc Clement、et al.
  • Journal Title: The Astronomical Journal Volume: 157 Issue: 6 Pages: 232-232
  • DOI: 10.3847/1538-3881/ab141b
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] OGLE-2015-BLG-1649Lb: A Gas Giant Planet around a Low-mass Dwarf (2019)
  • Author(s): Nagakane M.、et al.
  • Journal Title: The Astronomical Journal Volume: 158 Issue: 5 Pages: 212-212
  • DOI: 10.3847/1538-3881/ab4881
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] MOA-bin-29b: A Microlensing Gas-giant Planet Orbiting a Low-mass Host Star (2019)
  • Author(s): Kondo Iona、et al.
  • Journal Title: The Astronomical Journal Volume: 158 Issue: 6 Pages: 224-224
  • DOI: 10.3847/1538-3881/ab4e9e
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] OGLE-2018-BLG-1011Lb,c: Microlensing Planetary System with Two Giant Planets Orbiting a Low-mass Star (2019)
  • Author(s): Han Cheongho、et al.
  • Journal Title: The Astronomical Journal Volume: 158 Issue: 3 Pages: 114-114
  • DOI: 10.3847/1538-3881/ab2f74
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] OGLE-2017-BLG-0482Lb: A Microlensing Super-Earth Orbiting a Low-mass Host Star (2018)
  • Author(s): Han C.他
  • Journal Title: The Astronomical Journal Volume: 155 Issue: 5 Pages: 211-211
  • DOI: 10.3847/1538-3881/aabad2
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] A Likely Detection of a Two-planet System in a Low-magnification Microlensing Event (2018)
  • Author(s): Suzuki D.他
  • Journal Title: The Astronomical Journal Volume: 155 Issue: 6 Pages: 263-263
  • DOI: 10.3847/1538-3881/aabd7a
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] A Planetary Microlensing Event with an Unusually Red Source Star: MOA-2011-BLG-291 (2018)
  • Author(s): Bennett David P.他
  • Journal Title: The Astronomical Journal Volume: 156 Issue: 3 Pages: 113-113
  • DOI: 10.3847/1538-3881/aad59c
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] MOA-2015-BLG-337: A Planetary System with a Low-mass Brown Dwarf/Planetary Boundary Host, or a Brown Dwarf Binary (2018)
  • Author(s): Miyazaki S.他
  • Journal Title: The Astronomical Journal Volume: 156 Issue: 3 Pages: 136-136
  • DOI: 10.3847/1538-3881/aad5ee
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Microlensing Results Challenge the Core Accretion Runaway Growth Scenario for Gas Giants (2018)
  • Author(s): Suzuki, D., Bennett, D. P., Ida, S., et al.
  • Journal Title: The Astrophysical Journal Volume: 869 Issue: 2 Pages: L34-L34
  • DOI: 10.3847/2041-8213/aaf577
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] OGLE-2013-BLG-1761Lb: A Massive Planet around an M/K Dwarf (2017)
  • Author(s): Hirao Y.、et al.
  • Journal Title: The Astronomical Journal Volume: 154 Issue: 1 Pages: 1-1
  • DOI: 10.3847/1538-3881/aa73da
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] MOA-2016-BLG-227Lb: A Massive Planet Characterized by Combining Light-curve Analysis and Keck AO Imaging (2017)
  • Author(s): Koshimoto N.、et al.
  • Journal Title: The Astronomical Journal Volume: 154 Issue: 1 Pages: 3-3
  • DOI: 10.3847/1538-3881/aa72e0
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] MOA-2012-BLG-505Lb: A Super-Earth-mass Planet That Probably Resides in the Galactic Bulge (2017)
  • Author(s): Nagakane M.、et al.
  • Journal Title: The Astronomical Journal Volume: 154 Issue: 1 Pages: 35-35
  • DOI: 10.3847/1538-3881/aa74b2
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] The lowest mass ratio planetary microlens: OGLE 2016?BLG?1195Lb (2017)
  • Author(s): Bond I. A.、et al.
  • Journal Title: Monthly Notices of the Royal Astronomical Society Volume: 469 Issue: 2 Pages: 2434-2440
  • DOI: 10.1093/mnras/stx1049
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] OGLE-2016-BLG-1190Lb: The First Spitzer Bulge Planet Lies Near the Planet/Brown-dwarf Boundary (2017)
  • Author(s): Ryu Y.-H.、et al.
  • Journal Title: The Astronomical Journal Volume: 155 Issue: 1 Pages: 40-40
  • DOI: 10.3847/1538-3881/aa9be4
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Presentation] Unpublished binary and planetary events from MOA 9 year analysis (2019)
  • Author(s): Hirao, Y.
  • Organizer: 23rd International Microlensing Conference
  • Int'l Joint Research
• [Presentation] Analysis of the Planetary Microlensing Event OGLE-2017-BLG-0406 with Spitzer Data (2018)
  • Author(s): Hirao, Y.
  • Organizer: 22nd International Microlensing Conference
  • Int'l Joint Research
• [Presentation] WFIRST: Searching for Microlens Planets in Very Wide Orbits and the MOA Microlensing Data Release (2018)
  • Author(s): Hirao, Y.
  • Organizer: 231st AAS meeting
  • Int'l Joint Research