重力マイクロレンズによる地球質量系外惑星、浮遊惑星の探索

• Project/Area Number: 26247023
• Research Category: Grant-in-Aid for Scientific Research (A)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Astronomy
• Research Institution: Osaka University
• Principal Investigator: 住 貴宏 大阪大学, 理学(系)研究科(研究院), 准教授 (30432214)
• Project Period (FY): 2014-04-01 – 2017-03-31
• Project Status: Discontinued (Fiscal Year 2016)
• Budget Amount: ¥29,640,000 (Direct Cost: ¥22,800,000、Indirect Cost: ¥6,840,000); Fiscal Year 2016: ¥6,890,000 (Direct Cost: ¥5,300,000、Indirect Cost: ¥1,590,000); Fiscal Year 2015: ¥6,890,000 (Direct Cost: ¥5,300,000、Indirect Cost: ¥1,590,000); Fiscal Year 2014: ¥15,860,000 (Direct Cost: ¥12,200,000、Indirect Cost: ¥3,660,000)
• Keywords: 系外惑星 / 重力マイクロレンズ

Outline of Annual Research Achievements

本研究は、我々Microlensing Observations in Astrophysics (MOA)グループが行っている重力マイクロ レンズによる系外惑星探査を5年間継続して、系外惑星を多数発見し、I. スノーライ ンの外側で系外惑星の質量関数、軌道長半径分布を精度良く見積もる。スノーライン外側は惑星形成が活発で、多くの地球質量や海王星質量の惑星が形成されると考えられており、本研究により惑星形成理論に強い制限を与える。II.主星を伴わない浮遊惑星を数十個発見し、存在量、質量関数を見積もる。これにより、従来の観測で測られている「現在の惑星数」ではなく、元々惑星系でどれだけの惑星が形成されたかを見積もる事ができる。H26年度からH28年４月まで、銀河系バルジが観測可能な2月から11月に、日本のメンバーがNZに行くと同時にNZ 現地観測員を雇う事で、1.8m望遠鏡で22領域 (50平方度)を高頻度観測した。H26年度に設置した新たなフィルター交換機構で迷光が発生する問題が発見されたので、H27年度に改良版の製作と設置を行いV-bandでの観測を継続できる様にした。設置は順調に行われて、それ以後、毎晩V-bandでの観測を一晩に1回づつ行っている。このおかげで、検出されるイベントに関しては色の情報が得られる様になり信頼度が増した。これらの観測で、毎年約600個、合計約1200個のマイクロレンズイベントをリアルタイムで発見し、アラートを世界に発した。H26年は6個、H27年は8個の系外惑星を発見した。また、タイムスケール の非常に短い浮遊惑星候補も検出した。平成28年4月までの２年間に観測されたデータを再解析して、統計的にまとめる準備をしている。

Research Progress Status

28年度が最終年度であるため、記入しない。

Strategy for Future Research Activity

28年度が最終年度であるため、記入しない。

Research Products

• [Int'l Joint Research] マッシー大学/オークランド大学/カンタベリー大学(ニュージーランド)
• [Int'l Joint Research] ノートルダム大学/NASA(米国)
• [Int'l Joint Research] マッシー大学/オークランド大学/カンタベリー大学(ニュージーランド)
• [Int'l Joint Research] ノートルダム大学/NASA(米国)
• [Journal Article] The frequency of snowline-region planets from four years of OGLE-MOA-Wise second-generation microlensing (2016)
  • Author(s): Shvartzvald, Y.他
  • Journal Title: Monthly Notices of the Royal Astronomical Society Volume: 457 Issue: 4 Pages: 4089-4113
  • DOI: 10.1093/mnras/stw191
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Spitzer Observations of OGLE-2015-BLG-1212 Reveal a New Path toward Breaking Strong Microlens Degeneracies (2016)
  • Author(s): Bozza, V., et al
  • Journal Title: The Astrophysical Journal Volume: 820 Issue: 1 Pages: 79-88
  • DOI: 10.3847/0004-637x/820/1/79
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] MOA-2011-BLG-028Lb: A Neptune-mass Microlensing Planet in the Galactic Bulge (2016)
  • Author(s): Skowron, J., et al.
  • Journal Title: The Astrophysical Journal Volume: 820 Issue: 1 Pages: 4-16
  • DOI: 10.3847/0004-637x/820/1/4
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Spitzer Parallax of OGLE-2015-BLG-0966: A Cold Neptune in the Galactic Disk (2016)
  • Author(s): Street, R. A., et al.
  • Journal Title: The Astrophysical Journal Volume: 819 Issue: 2 Pages: 93-104
  • DOI: 10.3847/0004-637x/819/2/93
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Planet Sensitivity from Combined Ground- and Space-based Microlensing Observations (2015)
  • Author(s): Zhu, W., et al.
  • Journal Title: The Astrophysical Journal, Volume 814, Issue 2, article id. 129, 10 pp. (2015). Volume: 814 Issue: 2 Pages: 129-138
  • DOI: 10.1088/0004-637x/814/2/129
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] MOA-2010-BLG-353Lb: a possible Saturn revealed (2015)
  • Author(s): Rattenbury, N. J., et al.
  • Journal Title: Monthly Notices of the Royal Astronomical Society Volume: 454 Issue: 1 Pages: 946-951
  • DOI: 10.1093/mnras/stv2045
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Red Noise Versus Planetary Interpretations in the Microlensing Event Ogle-2013-BLG-446 (2015)
  • Author(s): Bachelet, E., et al.
  • Journal Title: The Astrophysical Journal, Volume 812, Issue 2, article id. 136, 11 pp. (2015). Volume: 812 Issue: 2 Pages: 136-146
  • DOI: 10.1088/0004-637x/812/2/136
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] OGLE-2012-BLG-0563Lb: A Saturn-mass Planet around an M Dwarf with the Mass Constrained by Subaru AO Imaging (2015)
  • Author(s): Fukui, A., et al.
  • Journal Title: The Astrophysical Journal, Volume 809, Issue 1, article id. 74, 16 pp. (2015). Volume: 809 Issue: 1 Pages: 74-89
  • DOI: 10.1088/0004-637x/809/1/74
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] MOA-2007-BLG-197: Exploring the brown dwarf desert (2015)
  • Author(s): Ranc, C., et al.
  • Journal Title: Astronomy & Astrophysics Volume: 580 Pages: 125-140
  • DOI: 10.1051/0004-6361/201525791
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Reanalyses of Anomalous Gravitational Microlensing Events in the OGLE-III Early Warning System Database with Combined Data (2015)
  • Author(s): Jeong, J., et al.
  • Journal Title: The Astrophysical Journal Volume: 804 Issue: 1 Pages: 38-48
  • DOI: 10.1088/0004-637x/804/1/38
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] OGLE-2011-BLG-0265Lb: A Jovian Microlensing Planet Orbiting an M Dwarf (2015)
  • Author(s): Skowron, J., et al.
  • Journal Title: The Astrophysical Journal, Volume 804, Issue 1, article id. 33, 12 pp. (2015). Volume: 804 Issue: 1 Pages: 33-44
  • DOI: 10.1088/0004-637x/804/1/33
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Pathway to the Galactic Distribution of Planets: Combined Spitzer and Ground-Based Microlens Parallax Measurements of 21 Single-Lens Events (2015)
  • Author(s): Calchi Novati, S., et al.
  • Journal Title: The Astrophysical Journal, Volume 804, Issue 1, article id. 20, 25 pp. (2015). Volume: 804 Issue: 1 Pages: 20-44
  • DOI: 10.1088/0004-637x/804/1/20
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Can the Masses of Isolated Planetary-mass Gravitational Lenses be Measured by Terrestrial Parallax? (2015)
  • Author(s): Freeman, M. et al.
  • Journal Title: The Astrophysical Journal Volume: 799 Issue: 2 Pages: 181-192
  • DOI: 10.1088/0004-637x/799/2/181
  • Peer Reviewed / Open Access / Acknowledgement Compliant
• [Journal Article] OGLE-2013-BLG-0102LA,B: Microlensing Binary with Components at Star/Brown Dwarf and Brown Dwarf/Planet Boundaries (2015)
  • Author(s): Jung, Y. K. et al.
  • Journal Title: The Astrophysical Journal Volume: 798 Issue: 2 Pages: 123-129
  • DOI: 10.1088/0004-637x/798/2/123
  • Peer Reviewed / Open Access / Acknowledgement Compliant
• [Journal Article] OGLE-2011-BLG-0265Lb: a Jovian Microlensing Planet Orbiting an M Dwarf (2015)
  • Author(s): Skowron, J. et al.
  • Journal Title: The Astrophysical Journal Volume: 未定
  • Peer Reviewed / Open Access / Acknowledgement Compliant
• [Journal Article] Candidate Gravitational Microlensing Events for Future Direct Lens Imaging (2014)
  • Author(s): Henderson, C. B. et al.
  • Journal Title: The Astrophysical Journal Volume: 794 Issue: 1 Pages: 71-81
  • DOI: 10.1088/0004-637x/794/1/71
  • Peer Reviewed / Open Access / Acknowledgement Compliant
• [Journal Article] A terrestrial planet in a ~1-AU orbit around one member of a ~15-AU binary (2014)
  • Author(s): Gould, A. et al.
  • Journal Title: Science Volume: 345 Issue: 6192 Pages: 46-49
  • DOI: 10.1126/science.1251527
  • Peer Reviewed / Open Access / Acknowledgement Compliant
• [Journal Article] MOA-2013-BLG-220Lb: Massive Planetary Companion to Galactic-disk Host (2014)
  • Author(s): Yee, J. C. et al.
  • Journal Title: The Astrophysical Journal Volume: 790 Issue: 1 Pages: 14-20
  • DOI: 10.1088/0004-637x/790/1/14
  • Peer Reviewed / Open Access / Acknowledgement Compliant
• [Journal Article] OGLE-2008-BLG-355Lb: A Massive Planet around a Late-type Star (2014)
  • Author(s): Koshimoto, N.; Udalski, A.; Sumi, T.; Bennett, D. P.; Bond, I. A.; Rattenbury, N.; Abe, andF.; Botzler, C. S.; Freeman, M.; Fukagawa, M.; Fukui, A.; Furusawa, K.; Itow, Y.; Ling, C. H.; Masuda, K.; Matsubara, Y.; Muraki, Y.; Ohnishi, K.; Saito, To.; Shibai, H.,…他17名
  • Journal Title: The Astrophysical Journal Volume: Volume 788, Issue 2 Issue: 2 Pages: 128-139
  • DOI: 10.1088/0004-637x/788/2/128
  • Peer Reviewed / Open Access
• [Journal Article] OGLE-2012-BLG-0455/MOA-2012-BLG-206: Microlensing Event with Ambiguity in Planetary Interpretations Caused by Incomplete Coverage of Planetary Signal (2014)
  • Author(s): Park, H.; Han, C.; Gould, A.; Udalski, A.; Sumi, T.; Fouqué, P.; Choi, J.-Y.; Christie, G.; Depoy, D. L.; Dong, Subo; Gaudi, B. S.; Hwang, K.-H.; Jung, Y. K.; Kavka, A.; Lee, C.-U.; Monard, L. A. G.; Natusch, T.; Ngan, H.,…他42名
  • Journal Title: The Astrophysical Journal Volume: Volume 787, Issue 1 Issue: 1 Pages: 71-76
  • DOI: 10.1088/0004-637x/787/1/71
  • Peer Reviewed / Open Access
• [Journal Article] MOA-2011-BLG-262Lb : A Sub-Earth-Mass Moon Orbiting a Gas Giant Primary or a High Velocity Planetary System in the Galactic Bulge (2014)
  • Author(s): Bennett, D. P., Sumi T. (26), Abe, F. (10) (95 authors)
  • Journal Title: ApJ Volume: 785, 155(refereed) Issue: 2 Pages: 13-13
  • DOI: 10.1088/0004-637x/785/2/155
  • Peer Reviewed / Open Access
• [Presentation] 海王星に似た惑星:MOA-2013-BLG-605Lbの公転軌道 (2016)
  • Author(s): Sumi T.
  • Organizer: 日本天文学会春季年会(
  • Place of Presentation: 首都大学東京
  • Year and Date: 2016-03-16
• [Presentation] Microlensing exoplanet search toward the solar system analog (2016)
  • Author(s): Sumi T.
  • Organizer: Exoplanets and Disks: Their Formation and Diversity III
  • Place of Presentation: Ishigaki, Okinawa
  • Year and Date: 2016-02-23
  • Int'l Joint Research / Invited
• [Presentation] Exoplanet Microlensing Context (2015)
  • Author(s): Sumi T.
  • Organizer: IAU General Assembly, WFIRST Splinter Session
  • Place of Presentation: Hawaii, United States
  • Year and Date: 2015-08-09
  • Int'l Joint Research / Invited
• [Presentation] MOA-2013-BLG-605Lb: T. Sumi, The Neptune analog (2015)
  • Author(s): Sumi T.
  • Organizer: IAU General Assembly(国際学会)
  • Place of Presentation: Hawaii, United States
  • Year and Date: 2015-08-03
  • Int'l Joint Research
• [Presentation] 重力マイクロレンズ探査で探る天の川銀河構造 (2015)
  • Author(s): Sumi T.
  • Organizer: 天の川銀河研究会
  • Place of Presentation: 東京大学、東京都
  • Year and Date: 2015-03-23
  • Invited
• [Presentation] MOA-2013-BLG-605Lb:The Neptune Analog (2015)
  • Author(s): Sumi T.
  • Organizer: 19th International Conference on Microlensing
  • Place of Presentation: The Maryland Inn-Historic Inns of Anapolis,USA
  • Year and Date: 2015-01-20
• [Presentation] WFIRST Wide-Field Infra-Red Survey Telescope (2015)
  • Author(s): Sumi T.
  • Organizer: 宇宙科学シンポジウム
  • Place of Presentation: 宇宙科学研究所、神奈川県
  • Year and Date: 2015-01-07
• [Presentation] MOA-IIによる系外惑星探査 (2014)
  • Author(s): Sumi T.
  • Organizer: 名古屋大学南半球宇宙観測研究センター研究会
  • Place of Presentation: 名古屋大学、愛知県
  • Year and Date: 2014-10-03
  • Invited
• [Presentation] MOA-2013-BLG-605Lb:晩期M型矮星に付随する海王星質量惑星 (2014)
  • Author(s): Sumi T.
  • Organizer: 日本天文学会秋季年会
  • Place of Presentation: 山形大学、山形県
  • Year and Date: 2014-09-12
• [Presentation] Free-floating planets (2014)
  • Author(s): Sumi T.
  • Organizer: American Astronomical Society Meeting(
  • Place of Presentation: the Westin Copley Place in Boston,USA
  • Year and Date: 2014-06-03
  • Invited