若い恒星まわりの系外惑星探査：新解析手法の確立とトランジット惑星観測

• Project Area: A Paradigm Shift by a New Integrated Theory of Star Formation: Exploring the Expanding Frontier of Habitable Planetary Systems in Our Galaxy
• Project/Area Number: 21H00035
• Research Category: Grant-in-Aid for Scientific Research on Innovative Areas (Research in a proposed research area)
• Allocation Type: Single-year Grants
• Review Section: Science and Engineering
• Research Institution: Center for Novel Science Initatives, National Institutes of Natural Sciences
• Principal Investigator: 平野 照幸 大学共同利用機関法人自然科学研究機構(新分野創成センター、アストロバイオロジーセンター、生命創成探究, アストロバイオロジーセンター, 准教授 (10727449)
• Project Period (FY): 2021-04-01 – 2023-03-31
• Project Status: Completed (Fiscal Year 2022)
• Budget Amount: ¥10,400,000 (Direct Cost: ¥8,000,000、Indirect Cost: ¥2,400,000); Fiscal Year 2022: ¥5,200,000 (Direct Cost: ¥4,000,000、Indirect Cost: ¥1,200,000); Fiscal Year 2021: ¥5,200,000 (Direct Cost: ¥4,000,000、Indirect Cost: ¥1,200,000)
• Keywords: 太陽系外惑星 / 散開星団 / トランジット惑星 / 近赤外分光 / 視線速度 / 惑星大気 / トランジット / 近赤外線観測 / 恒星活動 / 系外惑星 / 惑星形成

Outline of Research at the Start

本研究は，現在分かっている太陽系外惑星の分布や特徴を説明する理論仮説を検証することを主な目的として，年齢10億年未満の若い恒星まわりの短周期惑星の発見のための方法論の確立と新たに見つかる若い系外惑星の特徴付けに取り組む。具体的には，（A）若い恒星を対象とした将来的な視線速度サーベイのための方法論の整備と，（B）衛星ミッションで発見される若いトランジット惑星の軌道・大気等の特徴付けを目的とした地上観測を実施する。

Outline of Annual Research Achievements

本研究では，将来的な若い恒星まわりの太陽系外惑星の大規模な探査を念頭に置いて，(1)若い恒星に見られる視線速度ジッター（恒星活動による見かけ上の視線速度変化）の評価と抑制法の開発，(2)すでに見つかっている若いトランジット惑星の軌道・大気等の特徴付け，という2つのテーマに取り組んだ。(1)のテーマでは，すでに2022年度までの研究で視線速度ジッターの理論モデル計算等が完了していたため，2023年度はすばる望遠鏡近赤外分光器IRDで取得したいくつかの若い恒星のスペクトルを解析して，実際に理論モデルによる視線速度ジッターの振幅と観測される振幅がどの程度一致するか詳細に調査した。
(2)のテーマに関しては，以前IRDで取得していた若いトランジット惑星K2-33bのトランジット分光データを解析し，ロシター効果による軌道傾斜角の測定を行うとともに，透過光分光法を用いてK2-33bのヘリウム(I)外層大気を調査した。結果として，K2-33bの公転軸は主星（K2-33）の自転軸とほぼ揃っていること，K2-33bのトランジット中に主星のヘリウム吸収線で超過吸収が観測され，惑星は大規模な外層大気の散逸を経験していること，などが明らかとなった。

Research Progress Status

令和4年度が最終年度であるため、記入しない。

Strategy for Future Research Activity

令和4年度が最終年度であるため、記入しない。

Research Products

• [Int'l Joint Research] ハワイ大学(米国)
• [Int'l Joint Research] マギル大学(カナダ)
• [Int'l Joint Research] ジュネーブ大学(スイス)
• [Int'l Joint Research] ハワイ大学/カリフォルニア工科大学(米国)
• [Journal Article] TOI-544 b: a potential water-world inside the radius valley in a two-planet system (2023)
  • Author(s): Osborne H L M、Van Eylen V、Goffo E、Gandolfi D、Nowak G、Persson C M、Livingston J、Weeks A、Palle E、Luque R、Hellier C、Carleo I、Redfield S、Hirano T、et al.
  • Journal Title: Monthly Notices of the Royal Astronomical Society Volume: 527 Issue: 4 Pages: 11138-11157
  • DOI: 10.1093/mnras/stad3837
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Planetary companions orbiting the M dwarfs GJ 724 and GJ 3988 (2023)
  • Author(s): Gorrini P.、Kemmer J.、Dreizler S.、Burn R.、Hirano T.、et al.
  • Journal Title: Astronomy & Astrophysics Volume: 680 Pages: A28-A28
  • DOI: 10.1051/0004-6361/202347108
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] CO, H2O, and CH4 in the dusty atmosphere of a <5 Myr-old exoplanet (2023)
  • Author(s): Gaidos Eric、Hirano Teruyuki
  • Journal Title: Monthly Notices of the Royal Astronomical Society Volume: 525 Issue: 4 Pages: 6303-6311
  • DOI: 10.1093/mnras/stad2664
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] An M dwarf accompanied by a close-in giant orbiter with SPECULOOS (2023)
  • Author(s): Triaud Amaury H M J、Dransfield Georgina、Kagetani Taiki、Timmermans Mathilde、Narita Norio、Barkaoui Khalid、Hirano Teruyuki、et al.
  • Journal Title: Monthly Notices of the Royal Astronomical Society: Letters Volume: 525 Issue: 1 Pages: L98-L104
  • DOI: 10.1093/mnrasl/slad097
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] The Orbit of Warm Jupiter WASP-106 b is Aligned with its Star (2023)
  • Author(s): Harre Jan-Vincent、Smith Alexis M. S.、Hirano Teruyuki、Csizmadia Szilard、J. Triaud Amaury H. M.、Anderson David R.
  • Journal Title: The Astronomical Journal Volume: 166 Issue: 4 Pages: 159-159
  • DOI: 10.3847/1538-3881/acf46d
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Company for the Ultra-high Density, Ultra-short Period Sub-Earth GJ 367 b: Discovery of Two Additional Low-mass Planets at 11.5 and 34 Days* (2023)
  • Author(s): Goffo Elisa、Gandolfi Davide、Egger Jo Ann、Mustill Alexander J.、Albrecht Simon H.、Hirano Teruyuki、et al.
  • Journal Title: The Astrophysical Journal Letters Volume: 955 Issue: 1 Pages: L3-L3
  • DOI: 10.3847/2041-8213/ace0c7
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] The mass of TOI-519 b: A close-in giant planet transiting a metal-rich mid-M dwarf (2023)
  • Author(s): Kagetani Taiki、Narita Norio、Kimura Tadahiro、Hirano Teruyuki、et al.
  • Journal Title: Publications of the Astronomical Society of Japan Volume: 75 Issue: 4 Pages: 713-721
  • DOI: 10.1093/pasj/psad031
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Cerium Features in Kilonova Near-infrared Spectra: Implication from a Chemically Peculiar Star (2023)
  • Author(s): Tanaka Masaomi、Domoto Nanae、Aoki Wako、Ishigaki Miho N.、Wanajo Shinya、Hotokezaka Kenta、Kawaguchi Kyohei、Kato Daiji、Lee Jae-Joon、Lee Ho-Gyu、Hirano Teruyuki、et al.
  • Journal Title: The Astrophysical Journal Volume: 953 Issue: 1 Pages: 17-17
  • DOI: 10.3847/1538-4357/acdc95
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Overfitting Affects the Reliability of Radial Velocity Mass Estimates of the V1298 Tau Planets (2023)
  • Author(s): Blunt Sarah、Carvalho Adolfo、David Trevor J.、...、Hirano Teruyuki、et al.
  • Journal Title: The Astronomical Journal Volume: 166 Issue: 2 Pages: 62-62
  • DOI: 10.3847/1538-3881/acde78
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] A Spectroscopic Thermometer: Individual Vibrational Band Spectroscopy with the Example of OH in the Atmosphere of WASP-33b (2023)
  • Author(s): Ernst J. W.、Waldmann Ingo、Tennyson Jonathan、Kawahara Hajime、Kuzuhara Masayuki、Hirano Teruyuki、Kotani Takayuki、Kawashima Yui、Masuda Kento、Birkby Jayne L.、Watson Chris A.、Tamura Motohide、Zwintz Konstanze、Harakawa Hiroki、Kudo Tomoyuki、Hodapp Klaus、Jacobson Shane、Konishi Mihoko、Kurokawa Takashi et al.
  • Journal Title: The Astronomical Journal Volume: 166 Issue: 2 Pages: 41-41
  • DOI: 10.3847/1538-3881/acdb75
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] TOI-1130: A photodynamical analysis of a hot Jupiter in resonance with an inner low-mass planet (2023)
  • Author(s): Korth J.、Gandolfi D.、Subjak J.、...、Hirano T.、et al.
  • Journal Title: Astronomy & Astrophysics Volume: 675 Pages: A115-A115
  • DOI: 10.1051/0004-6361/202244617
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Absence of extended atmospheres in low-mass star radius-gap planets (2023)
  • Author(s): Krishnamurthy Vigneshwaran、Hirano Teruyuki、et al.
  • Journal Title: Monthly Notices of the Royal Astronomical Society Volume: 521 Issue: 1 Pages: 1210-1220
  • DOI: 10.1093/mnras/stad404
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] TOI-1442 b and TOI-2445 b: Two potentially rocky ultra-short period planets around M dwarfs (2023)
  • Author(s): Morello G.、Parviainen H.、Murgas F.、Palle E.、Oshagh M.、Fukui A.、Hirano T.、et al.
  • Journal Title: Astronomy & Astrophysics Volume: 673 Pages: A32-A32
  • DOI: 10.1051/0004-6361/202243592
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] High-resolution Transmission Spectroscopy of the Terrestrial Exoplanet GJ 486b (2023)
  • Author(s): Ridden-Harper, Andrew; Nugroho, Stevanus K.; Flagg, Laura; Jayawardhana, Ray; Turner, Jake D.; de Mooij, Ernst; MacDonald, Ryan; Deibert, Emily; Tamura, Motohide; Kotani, Takayuki; Hirano, Teruyuki; Kuzuhara, Masayuki; Omiya, Masashi; Kusakabe, Nobuhiko
  • Journal Title: The Astronomical Journal Volume: 165 Issue: 4 Pages: 170-170
  • DOI: 10.3847/1538-3881/acbd39
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Direct Imaging Explorations for Companions around Mid-Late M Stars from the Subaru/IRD Strategic Program (2023)
  • Author(s): Uyama Taichi、Beichman Charles、Kuzuhara Masayuki、Janson Markus、Kotani Takayuki、Mawet Dimitri、Sato Bun’ei、Tamura Motohide、Ishikawa Hiroyuki Tako、Cale Bryson、Currie Thayne、Harakawa Hiroki、Henning Thomas、Hirano Teruyuki、et al.
  • Journal Title: The Astronomical Journal Volume: 165 Issue: 4 Pages: 162-162
  • DOI: 10.3847/1538-3881/acbf37
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Elemental Abundances of nearby M Dwarfs Based on High-resolution Near-infrared Spectra Obtained by the Subaru/IRD Survey: Proof of Concept (2022)
  • Author(s): Ishikawa Hiroyuki Tako、Aoki Wako、Hirano Teruyuki、et al.
  • Journal Title: The Astronomical Journal Volume: 163 Issue: 2 Pages: 72-72
  • DOI: 10.3847/1538-3881/ac3ee0
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Tidal Effects on the Radial Velocities of V723 Mon: Additional Evidence for a Dark 3 M_sun Companion (2021)
  • Author(s): Masuda Kento、Hirano Teruyuki
  • Journal Title: The Astrophysical Journal Letters Volume: 910 Issue: 2 Pages: L17-L17
  • DOI: 10.3847/2041-8213/abecdc
  • Peer Reviewed
• [Journal Article] Mass and density of the transiting hot and rocky super-Earth LHS 1478 b (TOI-1640 b) (2021)
  • Author(s): Soto M. G.、Anglada-Escude G.、Dreizler S.、...., Hirano T., et al.
  • Journal Title: Astronomy & Astrophysics Volume: 649 Pages: A144-A144
  • DOI: 10.1051/0004-6361/202140618
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Joint Analysis of Multicolor Photometry: A New Approach to Constrain the Nature of Multiple-star Systems Hosting Exoplanet Candidates (2021)
  • Author(s): Miyakawa K. et al. (including Fukui A.)
  • Journal Title: The Astronomical Journal Volume: 161 Issue: 6 Pages: 276-276
  • DOI: 10.3847/1538-3881/abf500
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Hot planets around cool stars ? two short-period mini-Neptunes transiting the late K-dwarf TOI-1260 (2021)
  • Author(s): Georgieva I Y et al.
  • Journal Title: Monthly Notices of the Royal Astronomical Society Volume: 505 Issue: 4 Pages: 4684-4701
  • DOI: 10.1093/mnras/stab1464
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Nondetection of Helium in the Upper Atmospheres of TRAPPIST-1b, e, and f (2021)
  • Author(s): Krishnamurthy Vigneshwaran、Hirano Teruyuki、Stefansson Gumundur、et al.
  • Journal Title: The Astronomical Journal Volume: 162 Issue: 3 Pages: 82-82
  • DOI: 10.3847/1538-3881/ac0d57
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Wavelength Dependence of Activity-induced Photometric Variations for Young Cool Stars in Hyades (2021)
  • Author(s): Miyakawa K. et al. (including Fukui A.)
  • Journal Title: The Astronomical Journal Volume: 162 Issue: 3 Pages: 104-104
  • DOI: 10.3847/1538-3881/ac111d
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] The Youngest Planet to Have a Spin-Orbit Alignment Measurement AU Mic b (2021)
  • Author(s): Addison Brett C.、Horner Jonathan、Wittenmyer Robert A.、Heitzmann Alexis、Plavchan Peter、Wright Duncan J.、Nicholson Belinda A.、Marshall Jonathan P.、Clark Jake T.、Guenther Maximilian N.、Kane Stephen R.、Hirano Teruyuki、et al.
  • Journal Title: The Astronomical Journal Volume: 162 Issue: 4 Pages: 137-137
  • DOI: 10.3847/1538-3881/ac1685
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Two Bright M Dwarfs Hosting Ultra-Short-Period Super-Earths with Earth-like Compositions* (2021)
  • Author(s): Hirano T et al.
  • Journal Title: The Astronomical Journal Volume: 162 Issue: 4 Pages: 161-161
  • DOI: 10.3847/1538-3881/ac0fdc
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Masses and compositions of three small planets orbiting the nearby M dwarf L231-32 (TOI-270) and the M dwarf radius valley (2021)
  • Author(s): Van Eylen V et al.
  • Journal Title: Monthly Notices of the Royal Astronomical Society Volume: 507 Pages: 2154-2173
  • DOI: 10.1093/mnras/stab2143
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Zodiacal Exoplanets in Time (ZEIT). XIV. He I Transit Spectroscopy of the 650 Myr Hyades Planet K2-136c (2021)
  • Author(s): Gaidos Eric、Hirano Teruyuki、Omiya Masashi、Kuzuhara Masayuki、Kotani Takayuki、Tamura Motohide、Harakawa Hiroki、Kudo Tomoyuki
  • Journal Title: Research Notes of the AAS Volume: 5 Issue: 10 Pages: 238-238
  • DOI: 10.3847/2515-5172/ac31bd
  • Open Access / Int'l Joint Research
• [Journal Article] 37 new validated planets in overlapping <i>K2</i> campaigns (2021)
  • Author(s): de Leon J P et al.
  • Journal Title: Monthly Notices of the Royal Astronomical Society Volume: 508 Issue: 1 Pages: 195-218
  • DOI: 10.1093/mnras/stab2305
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Diving Beneath the Sea of Stellar Activity: Chromatic Radial Velocities of the Young AU Mic Planetary System (2021)
  • Author(s): Cale Bryson L.、Reefe Michael、Plavchan Peter、..., Hirano Teruyuki, et al.
  • Journal Title: The Astronomical Journal Volume: 162 Issue: 6 Pages: 295-295
  • DOI: 10.3847/1538-3881/ac2c80
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] GJ 367b: A dense, ultrashort-period sub-Earth planet transiting a nearby red dwarf star (2021)
  • Author(s): Lam K W F et al.
  • Journal Title: Science Volume: 374 Issue: 6572 Pages: 1271-1275
  • DOI: 10.1126/science.aay3253
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Zodiacal exoplanets in time ? XIII. Planet orbits and atmospheres in the V1298?Tau system, a keystone in studies of early planetary evolution (2021)
  • Author(s): Gaidos E et al.
  • Journal Title: Monthly Notices of the Royal Astronomical Society Volume: 509 Issue: 2 Pages: 2969-2978
  • DOI: 10.1093/mnras/stab3107
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] TOI-2285b: A 1.7 Earth-radius planet near the habitable zone around a nearby M dwarf (2021)
  • Author(s): Fukui A et al.
  • Journal Title: Publications of the Astronomical Society of Japan Volume: 74 Issue: 1 Pages: L1-L8
  • DOI: 10.1093/pasj/psab106
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Presentation] Helium Transmission Spectroscopy for Young Planets (2024)
  • Author(s): 平野照幸
  • Organizer: 2024年冬季トランジット惑星研究検討会
  • Invited
• [Presentation] 近赤外視線速度測定・黒点由来のRVジッターの波長依存性について (2024)
  • Author(s): 平野照幸
  • Organizer: Extreme Precision Radial Velocity (EPRV) ワークショップ
• [Presentation] 近赤外透過光分光による惑星大気散逸の観測 (2024)
  • Author(s): 平野照幸，すばる/IRDチーム
  • Organizer: 名大ISEE研究集会「宇宙プラズマ・恒星放射が惑星超高層大気・衛星表層環境に及ぼす影響」
• [Presentation] Analytic Description of Radial Velocity Jitters (2023)
  • Author(s): Teruyuki Hirano, Eric Gaidos, Hiroki Harakawa, Takayuki Kotani, Masayuki Kuzuhara, Masashi Omiya, Motohide Tamura
  • Organizer: Protostars and Planets VII
  • Int'l Joint Research
• [Presentation] 系外惑星上層大気の観測と大気散逸 (2023)
  • Author(s): 平野照幸，福井暁彦，川内紀代恵，Eric Gaidos, Vigneshwaran Krishnamurthy，すばる/IRDチーム
  • Organizer: 日本天文学会2023年秋季年会
  • Invited
• [Presentation] Chromatic Measurements of Radial-Velocity Jitter (2023)
  • Author(s): Teruyuki Hirano, IRD team
  • Organizer: the 14th RESCEU International Symposium
  • Int'l Joint Research
• [Presentation] 若い系外惑星系の観測：恒星活動の波長依存性 (2023)
  • Author(s): 平野照幸
  • Organizer: 新学術領域「星・惑星形成」2023年度大研究会
• [Presentation] Exoplanet detection and characterization by the InfraRed Doppler (IRD) instrument on Subaru (2023)
  • Author(s): Teruyuki Hirano
  • Organizer: Exoplanets & Planet Formation Workshop 2023
  • Int'l Joint Research / Invited
• [Presentation] 近赤外分光による若い系外惑星の観測 (2022)
  • Author(s): 平野照幸
  • Organizer: 新学術領域「星・惑星形成」2021年度大研究会
  • Invited
• [Presentation] Follow-up Observations of Transiting Planet Candidates Identified by K2 (2022)
  • Author(s): Teruyuki Hirano & KESPRINT consortium
  • Organizer: 第10回 宇宙における生命ワークショップ
• [Presentation] JASMINE衛星による精密測光観測 (2022)
  • Author(s): 平野照幸，河原創，上塚貴史，大澤亮，片坐宏一，Exo-JASMINEチーム
  • Organizer: 日本天文学会2022年春季年会
• [Presentation] 若い恒星まわりの系外惑星探査：新解析手法の確立とトランジット惑星観測 (2021)
  • Author(s): 平野照幸
  • Organizer: 新学術「星惑星形成」後半戦キックオフミーティング
• [Presentation] 系外惑星探査におけるデータ科学手法 (2021)
  • Author(s): 平野照幸
  • Organizer: 惑星科学と情報基盤シンポジウム
  • Invited
• [Presentation] 低質量星まわりの系外惑星探査：近赤外線観測が切り開く系外惑星科学のフロンティア (2021)
  • Author(s): 平野照幸
  • Organizer: 日本惑星科学会2021年秋季講演会
  • Invited