星形成・惑星・太陽系班報告 TMTによる太陽系外惑星の探究 成田憲保（国立天文台） ＆星形成・惑星・太陽系班メンバー

“星と惑星の誕生、そしてその環境に迫る” 星形成・惑星・太陽系班 活動報告 グループ会議履歴 第1回　5月14日(金)　08:15-10:00　三鷹解析棟+TV-con 議題：班員紹介、検討班の方針とスケジュール決定、 第2回　6月14日(月)　08:00-10:00　三鷹解析棟+TV-con 議題：サイエンストピックスの決定と分担 第3回　8月 5日(木)　13:00-18:00　三鷹解析棟 議題：班員によるサイエンス検討状況発表 第4回　12月 10日(木)　13:00-18:00　三鷹解析棟 議題：報告書原稿の確認とフィードバック 星形成・惑星・太陽系班 キャッチフレーズ “星と惑星の誕生、そしてその環境に迫る”

Star/Planet Formation Science Group Members Star/Planet Formation T. Fujiyoshi M. Fukagawa S. Hirahara M. Honda S. Inutsuka T. Muto H. Nomura Y. Oasa T. Pyo Y. Takagi M. Takami Exoplanets T. Matsuo N. Narita B. Sato T. Sumi T. Yamashita Solar System Y. Kasaba T. Sekiguchi T. Terai

Science Topics of Star Formation Search for new interstellar molecules by high-dispersion Mid-IR spectroscopic observation Initial Mass Function (IMF), Masses and Ages of Young Stars The Solution to The Angular Momentum Problem in Star Formation: Jets and Outflows from Young Stellar Objects High Mass Star Formation

Science Topics of Planet Formation Observation of the Detailed Morphology of Circumstellar Disks Observations of the Spatial Distributions of Dust and Ice Grains in the Protoplanetary Disk Mapping the magnetic field in the circumstellar disks by MIR polarimetry Observations of H2 Line Emission to Probe Gas Dispersal Mechanism of Protoplanetary Disks Spatial Distribution of Organic Molecules in Protoplanetary Disks

Science Topics of Exoplanets Exoplanet Searches with Precise RV Method High resolution spectroscopy of exoplanet biomarkers at transits Search for Biomarkers in Habitable Exoplanet Atmospheres by Multi-Object Spectroscopy High Dispersion Spectroscopy of Sodium Atmospheric Absorption in Exoplanet Atmospheres Uncovering Migration Mechanisms of Earth–like Planets by the Rossiter-McLaughlin Effect Direct Imaging Survey of Terrestrial Planets in Habitable Zone Study of Exoplanet Distribution by Identifying the Host Stars of Planetary Gravitational Microlensing Events Direct imaging and low resolution spectroscopy of exoplanets in the mid-infrared

Science Topics of Solar System High Spatial Resolution Imaging for Small Solar System Bodies and Dwarf Planets High Spatial Resolution Imaging for Planets and Satellites High Spectral Resolution Spectroscopy of Atmospheres of Planets and Satellites

Exploring (Earth-like) Exoplanets RV search for new low-mass planets Transit follow-up studies Gravitational microlensing follow-up studies Direct imaging studies

Exoplanet Searches with Precise RV Method Precise Radial Velocity Measurements High-dispersion spectrograph with very precise wavelength calibration is required Ultimate precision depends on S/N of stellar spectrum Huge aperture of TMT enables us to observe faint stars with high S/N Targets: low-mass stars, stars in clusters, microlense objects, etc. observe relatively bright stars with ultra high S/N (ultra high precision) Targets: solar-type stars, giants and subgiants, early-type stars etc.

Detecting Earth-mass Planets in HZ RV semi-amplitude of host stars by companions in HZ Infrared preferred Optical preferred blue dashed 10ME 5ME red solid 3ME 2ME 1ME M6 M5 M0 K0 G0 F0

Detecting Earths around Solar-type Stars by Optical-RV Method: Targets ESO 3.6m+HARPS-type 3800-6900Å, R=115,000, Simultaneous Th-Ar method Texp=900s, σ=1m/s  mv~10 Subaru 8.2m+HDS-type 5100-5700Å, R=100,000, Iodine Cell Texp=1800s, σ=0.1m/s ESO(3.6m)+HARPS-type  mv~5--6 VLT(8m)+HARPS-type  mv~7.5 E-ELT(42m)+HARPS-type  mv~11 Subaru(8.2m)+HDS-type  mv~5--6 TMT(30m)+HDS-type  mv~8.5 太陽型振動をキャンセルするには約1800秒の露出が必要 つまり、口径によらずこのくらいの露出時間が必要なので、口径によって適した明るさがあるというのがミソ At least ~1800 s exposure is required to average out stellar p-mode oscillation down to <0.2 m/s level (Mayor & Udry 2008)

Searching for Habitable Earths around M Stars by IR-RV Method: Targets Data from Lepine et al. (2005) Mv=130.3M  Subaru 2871 stars 1630 stars Mv=16 0.1M  TMT 1m/sの精度で1Mearthをみつけられるのは0.1Msun周り 8m クラスだと主なターゲットはJ<10で0.3Msun辺りになるが、TMTだとJ<13-14までとなり0.1Msunのターゲット数もそれなりの数になる すばるIRDのことは話してよいと思います 2534 stars 3039 stars TMT has many target stars for which we can search for habitable earths.

Planetary Transit Follow-up Transmission spectroscopy method to observe exoplanetary atmospheres high spectral resolution (HROS, NIRES, etc) MOS (WFOS/MOBIE, IRMOS etc) Rossiter effect method to observe exoplanetary orbital tilts precise RV measurements during transits

Transmission Spectroscopy star One can probe atmospheres of transiting exoplanets by comparing spectra between during and out of transits.

Targets and Methods Target Stars: Earth-like planets in HZ M stars: favorable Solar-type stars: difficult Target lines molecule lines in NIR oxygen A lines sodium D lines Methods High Dispersion Spectroscopy Multi-Object Spectroscopy

Rossiter effect of transiting planets the planet hides an approaching side → the star appears to be receding the planet hides a receding side → the star appears to be approaching planet star One can measure the obliquity of the planetary orbit relative to the stellar spin. The obliquity can tell us orbital evolution mechanisms of exoplanets.

What we learned from the Rossiter effect For Jovian planets, tilted or retrograde planets are not so rare (1/3 planets are tilted) How about low-mass planets?

Detectability of the Rossiter effect Current Opt. RV Subaru IR RV TMT IR (1m/s) TMT opt. (0.1m/s) F, G, K Jupiter ○ Neptune △ Earth × M ○：mostly possible, △：partially possible, ×：very difficult

Planetary Microlensing Follow-up 0.5 Ground-based surveys (e.g., OGLE, MOA) and future space-based survey (e.g. WFIRST) will find many planets via this method

Planet Distribution RV transit Direct image Microlensing： 　　Mass measurements 　　Mass by Bayesian Only half of planets have mass measurements. Need to resolve lens star to measure lens and planet’s mass! 1

TMT can resolve source and lens star Average relative proper motion of lens and source star: μ=6±4mas/yr Resolution: 1.2x2.2μm/8.2m= 66mas (~80mass in VLT/NACO and Keck AO) 1.2x2.2μm/30m=18mass Required time to separate by 2×psf: 8.2m: T8.2= 22+44-9 yr 30m: T30 = 6+12-2 yr

Direct Imaging TMT/PFI can resolve outer side of planetary systems Also, TMT may be able to detect a second Earth around late-type stars　-> Talk by Matsuo

使いたい観測装置 可視高分散分光器 (HROS) ４ 近赤外高分散分光器 (NIRES) ３ 高コントラスト・高空間分解能撮像装置 (PFI/SEIT) 2 広視野可視多天体分光器 (WFOS-MOBIE)　１ 広視野撮像装置 (WIRC)　１ 広視野近赤外多天体分光器 (IRMOS) L バンド分光・撮像装置

日本の独自性と戦略 TMTの本格稼働前にすばる望遠鏡などでどれだけ独自のター ゲットとなる惑星を発見できるかが重要 すばる望遠鏡IRDによる視線速度サーベイ MOAによるマイクロレンズサーベイ 岡山などでのトランジットサーベイ すばる望遠鏡で木星型・海王星型惑星に対する観測を進め TMT稼働後すぐに地球型へ挑戦 観測提案の土台となる方法論の確立・スキル・結果が大事

まとめ 系外惑星に対するサイエンスは、視線速度・トランジット・マイクロレンズ・直接撮像からそれぞれ提案された TMTの集光力、空間分解能、新装置によって、より小さくて軽い系外惑星（＝地球型惑星）の研究へのブレイクスルーが期待される