Exoplanet Research with TMT Jianghui JI ( Purple Mountain Observatory, Chinese Academy of Sciences ) 2014/01/13, TMT-Planetary Science Definition Workshop, Beijing Outline Introduction Overview of our work Scientific issues with TMT Summary Detected exoplanets As of 12 Jan., 1056 planets / 175 multiple planetary systems Radial velocity or Astrometry: 539 planets orbiting 405 stars Transit technique: 430 planets orbiting 327 stars Akeson et al., 2013, PASP Scientific Issues • 空间与地面的大量观测与统计表明，在恒星附近有很多短周期气态 巨行星、类地行星。这些行星是在当地（in-situ）形成还是在行星 盘经历了轨道迁移，抑或是引力不稳定性导致？ •在迁移过程中原行星是否仍然吸积盘中气体而继续生长？什么动力 学机制使行星轨道迁移停止？ • 短周期行星长期潮汐和动力学演化状况如何？ •它们内部结构与物质分布如何，与太阳系行星有何异同？ •大气成分有何特征，是否存在水、二氧化碳、甲烷、氧气等适合生 命存在的重要化学指纹？ •是否可以发现宜居的地球大小的行星？ Current Research and Future Projects Current Research: Dynamics and evolution of planetary system, Internal structure of terrestrial planets, Planetary atmosphere and spectroscopy, Follow-up Observations Future Projects: Atmosphere modelling and retrieval Transit follow-up observations: TrES-3b (In collaboration with NTHU, Taiwan) TrES-3 b transit event on Oct. 9, 2010, observed by 105/120 cm telescopic finder with 4K×4K drift scanning CCD finder at Xuyi Observation Station, Purple Mountain Observatory. Curve fitted and physical parameters derived using tools supplied by TRESCA database. Jiang et al., 2013, AJ Catalogue data Measured data Rp: 1.295 +/- 0.081 RJup 1.183 -0.039+0.038 RJup R*: 0.813 +/- 0.027 RSun fixed, errors included in i A: 0.0226 +/- 0.0013 AU fixed, errors included in i Per: 1.30619 days i: 82.15 +/- 0.21 ° fixed 1 81.77 -0.34|1.64+0.37|1.70 ° Planetary migration Ou, Ji et al. (2007), ApJ Kley et al. (2004), A&A Close-in planets formation: a new mechanism A new mechanism is revealed by which the collision–merger of planetary embryos can kick terrestrial planets directly into orbits extremely close to their parent stars. Ji, Jin &Tinney, 2011, ApJ Kepler planets formation: 1:2:4 MMRs The system of KOI-152 • • • Final locations of three planets Three planets are assumed to have formed in the region away from the star. Planets undergo type I migration. Three planets are trapped into MMRs during the migration. tidal effects, arising from the central star, circularize their orbits. Wang, Ji & Zhou, 2012, ApJ Evolution of three planets Tidal evolution of Kepler-10 system Dong & Ji, 2012, MNRAS Time variations of a1 and e1 with various eccentricity pairs a2 and e2 remain almost constant because of its far distance from the star Numerical results are consistent with those from the general secular theory Planet population synthesis coupled with evaporation Left: Temporal evolution of a synthetic planet population Right: Radius Distribution Compared with the Kepler Candidates Evaporation could lead to a bimodal distribution in planet size Jin et al. in prep Planetary internal structure We propose three possible internal structure models for Europa. Jin & Ji, 2012, Sci China-phys Mech Astron Mass-radius relationship of terrestrial plants and the Kepler detections. Jin & Ji, in prep. Constrain the planet structure Lissauer et al. 2013, ApJ From Wikipedia •Find the possible structure of a planet in combination with the possible formation scenarios. •Does a planet have a atmosphere? Can the pressure and temperature at the bottom of the atmosphere support liquid water? TMT Science I: Primary eclipse and secondary eclipse Transmission Spectrum, HD 189733b Swain et al. 2008, Nature • Planet mass and radius are the only information that we could get. However, there is large degeneracy in them (Valencia 2007; Seager 2007) • One possible way to break this degeneracy is try to get the bulk composition of the planet through spectroscopy. Thermal Emission, HD 189733b Madhusudhan & Seager 2009, ApJ Transit observations reveal a cloudy atmosphere Kreidberg et al. 2014, Nature Transit observations with the Wide Field Camera 3 (WFC3) show that the super-Earth planet GJ 1214b may contain clouds in its atmosphere. Featureless transmission spectrum of GJ 436b also suggests a cloudy atmosphere. Knutson et al. 2014, Nature TMT Science II: Direct Imaging HR 8799 direct imaging planets detections. Marios et al. 2008, Science; Marios et al. 2010, Nature • Obtain the luminosity and spectroscopic information of a planet. • Provide us clues about the atmospheric chemistry and composition. • Planet luminosity at young age could help us to distinguish how it is formed, by core accretion (cold start) or by gravitational instability (hot start). Ongoing project in our group: atmosphere modeling and spectroscopy PT structure of HD 209458b: Pressure-Temperature (PT) structure of HD 209458b. (Moses et al. 2012 ApJ) PT structure of HD 209458b from our calculation. For spectroscopy study, the red p-T profile is used (nominal model). Chemical abundance under thermochemical equilibrium: Moses et al. 2012 ApJ Calculation assuming solar abundances for the chemical elements in planet atmosphere. Moses et al. 2012 ApJ Calculation assuming solar abundances for the chemical elements in planet atmosphere. Our work: a forward spectroscopy model Emergent spectrum and observational data of HD 189733b. Moses et al. 2012, ApJ For comparison, we superimpose our result, the green line, in this Figure. The next step: Planet Atmosphere Retrieval • First: substitute 2-band atmosphere profile with the nongrey model. (Parmentier & Guillot 2013) • Second: combine the MCMC with our forward model to build an atmospheric retrieval program. (Madhusudhan & Seager 2009) Best-fit after MCMC run Modeled by Madhusudhan N. TMT Science I I I : Habitable Planets Planet with sufficient atmosphere that can support liquid water on their surfaces. About 5.7% stars have planets with P = 200-400 d, Rp = 1-2 RE. Kasting et al. 1993, Icarus Petigura et al. 2013, ApJ Petigura et al. 2013, PNAS TMT ScienceＩＶ: 小行星直接成像？ 采用光变曲线反演的方法获得了1996FG3的三维形状模型 采用已获得的7条光变曲线进行 反演 同时获得了该小行星的自转轴指 向为（237.70， -83.80） 与雷达图像比较显示：两者都存 在中间的隆起结构。 图中显示的是形状从四个不同的角度的图像 Arecibo获得的1996 FG3的雷达图像 TMT Ｖ: 小行星表面热物理性质研究 利 用 热 物 理 模 型 拟 合 Wolters et al (2011)和Walsh et al (2012)公开的三 组中红外数据，得到了1996 FG3的 如下表面物理性质： Summary • Transit observations and spectroscopy study could reveal the atmospheric feature and composition of close-in exoplanets (gas-giants, super-Earths and Earth analogs ). • Direct imaging will obtain the luminosity and the spectroscopic information of a planet at large separations, especially at young ages. • A lot of theoretical studies are required, such as atmospheric chemistry, atmospheric circulation, spectroscopy and retrieval, radiation transfer, etc. • TMT will definetely provide us a good opportunity to extensively investigate exoplanets, understand the complexity and diversity of planetary systems, to detect Earth-like planets in HZs. 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