General Basic Frontier in Exoplanet Characterization Advanced Hajime Kawahara RESCEU Online Summer School 2020 PurposeBasic Why Exoplanets? Universality of Us and Where We Live in “Exoplanet Characterization” Like Earth? Water, oxygen? Has ocean? Comfortable? Like Jupiter? Very different? 1/36 ContentsBasic 1. What kind of exoplanets can we characterize? Landscape of transit/directly-imaged exoplanets 2. How do we characterize exoplanets? Established techniques for exoplanet characterization 3. How will we characterize exoplanets? On-going and future techniques toward exo Earths Transit exoplanet Direct imaging Basic Exoplanet landscape Planet temperature 1600K 800K Log Stellar Mass (radius) 100K Hot Jupiter Jupiter & Neptune 1Msun (1Rsun) Super Earth 0.1Msun (0.1Rsun) 0.01 AU 0.1 AU 1 AU Distance from a star (log) Basic Exoplanet landscape (solar-type star by Kepler) 1au 2au 5au 0.39+-0.07 planets/star Hot Jupiter (~0.005 p/s) assuming 100% completeness Consistent with RV 10 Long-period planet in Kepler Super Earth (~ 0.7 p/s) Kepler original Planet Radius (Earth) Radius Planet 1 E 1 10 100 1000 Orbital period (d) Kepler prime mission Kawahara and Masuda (2019) Basic Exoplanet landscape (solar-type star) 1au 2au 5au 0.39+-0.07 planets/star Hot Jupiter (~0.005 p/s) assuming 100% completeness Consistent with RV 10 Neptune-sized Planets are common at Jupiter position (>~0.5 p/s) Super Earth (~ 0.7 p/s) Kepler original Planet Radius (Earth) Radius Planet 1 E 1 10 100 1000 Orbital period (d) Controversial Kepler prime mission Kawahara and Masuda (2019) Basic Exoplanet landscape Planet temperature 1600K 800K Log Stellar Mass Self-Luminous (radius) Planets 100K Hot Jupiter Jupiter & Neptune 1Msun (1Rsun) Super Earth Earth@low mass star? 0.1Msun (0.1Rsun) 0.01 AU 0.1 AU 1 AU Distance from a star (log) Basic Exoplanet landscape (schematic) Planet temperature 1600K 800K Log Stellar Mass Self-Luminous Planets (radius) 1000K 100K Hot Jupiter Super Earths Neptune & Jupiter Direct Imaging 1Msun from ground (1Rsun) Earth 1995- Kepler (2009-2013) PLATO TESS(2018-) TOI-700 system (TESS) Exo JASMINE 0.1Msun (0.1Rsun) Trappist-1 system (Ground) 0.01 AU 0.1 AU 1 AU Distance from a star (log) Advanced Fill a gap by Exo JASMINE TOI-700: Bright but small signal (depth=0.05%) TESS 0.6-1.0 um 10cm all-sky TESS↓ Exo JASMINE 1.1-1.7um 30cm Grounds <0.9um 1m class Depth=0.3 – 0.1 % Mag = 8 - 11 Exo JASMINE 探査領域 Trappist system Ground+Spitzer→ Large signal (depth=1%) but faint Basic Exoplanet landscape (schematic) Planet temperature 1600K 800K Log Stellar Mass Self-Luminous Planets (radius) 1000K 100K Hot Jupiter Super Earths Neptune & Jupiter Direct Imaging 1Msun from ground (1Rsun) Earth 1995- Kepler (2009-2013) PLATO TESS(2018-) TOI-700 system (TESS) Exo JASMINE 0.1Msun (0.1Rsun) Trappist-1 system (Ground) 0.01 AU 0.1 AU 1 AU Distance from a star (log) Short Summary Exoplanet landscape - Jupiter in solar system is universal. Super Earth < 1 AU and cool Neptune @ several AU, which do not exist in solar system, are also common. - Current astronomers are trying to cheat with Earths around low-mass stars or young self-luminous planets because it’s easy to observe. - Earth not yet 6/36 Basic Transit or directly-imaged planet exists. So next? You do not care? If we find exo-Earths, we want to know Molecules in atmosphere Radius/mass H2O or O2 (biosignature) Surface environment Atmosphere, climate Continents/ocean HD XXXXXX b You might care Exo Earth not yet. Lesson using other exoplanets Hot Jupiters and self-luminous planets are mainly used in reality directly-imaged planet Basic Beyond mass/radius Log Stellar Spectroscopy of star+planet Mass Self-Luminous Planets (radius) 1000K Hot Jupiter Super Earths Neptune & Jupiter 1Msun (1Rsun) Earth TOI-700 system (TESS) 0.1Msun (0.1Rsun) Trappist-1 system (Ground) 0.01 AU 0.1 AU 1 AU Distance from a star (log) Basic History/Future of Characterization by Transit Exoplanets Low-Res Spectroscopy (space) 2001 K, H2O 2014 2017 - 2020 ARIEL ~1m HD209458b Clouds/haze Trappist-1 （２０２８） Detection of Na in Hot Planets 7 rocky planetsJWST 6.5m OST・LUVOIR？ HST, 26 ppm （２０２１） Spitzer 15 ppm Ground 1.2m High-Res Spectroscopy (ground) CO, H2O, TiO, Metals, HCN, CH4 Space 1 m Transit Survey Heng and Winn 2009 2018 Late 2020-2030 Kepler TESS PLATO (CHEOPS) (Exo JASMINE) Basic Low-R Spectroscopy from space (transmission) Hot Jupiters Transmission Transit depth difference< 0.1% tmosphere tmosphere const.) height (+ a Insensitive to temperature structure Relative Relative Sensitive to molecules at higher atmosphere Total modeling required Wavelength (nm) Sing+18 Basic Low-R Spectroscopy from space (emission) Hot Jupiters Emission star Integrated blackbody Sensitive to temperature structure Sensitive to molecules at mid atmosphere Parmentier+18 Basic Atoms/Molecules detection using High-R Spectroscopy R = λ/Δλ ~ 100,000, Δλ ~ linewidth The best one so far. Hot Jupiter KELT9b Fe+ High-Resolution Spectra (HRS) Stellar : Planet ~ 1000 : 1 orbital phase transit wavelength - ＊ In Theoretical spectrum Molecule-by- Molecule Frames(phase) detection Fe+ wavelength velocity Vr (km/s) Hoeijmakers+2018 ＝ Vr = Kp cos(phase) + V0 Planetary wind -50 0 50 (km/s) (a few km/s) can CCF CCF signal Plant Radial Velocity be detectable (km/s) Pro: High-frequency signal is stable Kp even for ground-based observation V0 (km/s) Basic HRS Thermal Inversion by Titanium Oxide WASP33b emission using Subaru/HDS = star : planet ~ 1000 : 1 upper hotter + lower hotter - Nugroho, H.K.+ 2017, AJ Intensity at the line center Ishizuka, H.K.+ in prep comes from upper atmosphere Titanium oxide absorbs blue light and heats the upper atmosphere, like O3 on Earth. Short Summary LRS from space: metals, H2O, haze, scattering, black body Pros: intuitive, can detect continuum (haze, clouds, scattering) Cons: Total modeling required -> weak for systematics Toward exo Earth: JWST will try to detect molecules in terrestrial planets @ late-M Larger telescope is justice (LUVIOR…) HRS from ground: CO, H2O, TiO, HCN, CH4, metals, ions, T-P structure Pros: molecules even with many lines, no need of total modeling Cons: connection with model is much more difficult Toward exo Earth: Applicable to water detection(many lines). Larger telescope is justice (TMT, E-ELT) 14/36 Basic History and future of direct imaging 1st gen 2nd gen (AO only) (ExAO+coronagraph) Ground 2007 2014 2018 Space HR8799 51 Eri b PDS70 b 2025 2035-45 Roman HabEx or telescope LUVOIR Planets by reflection light Self-luminous young planets (T ~ 1000 K) Basic Why is the detection limited so far? Inner Working Angle ∝ λ/D Telescope Young hot planet size (emission) Inst dev Almost no signal Jupiters to be detectable at any Earths to be detectable at any Sudden open like gravitational waves (my hope, not yet) Basic Complex amplitude: 퐴 푥 = 푎 푒휙 푥 2 nd gen: Adaptive Optics, Optics, Coronagraph Adaptive gen: Classical AO Extreme AO Phase correction @ pupil correction Phase by a a mirrordeformableby Coronagraph Basic Complex amplitude: 퐴 푥 = 푎 푒휙 푥 2 nd gen: Adaptive Optics, Optics, Coronagraph Adaptive gen: pupil Focal plane Focal Classical AO Extreme AO pupil Coronagraph Focal plane Focal Basic Why is direct imaging worth? Greenbaum+2018 Spectrum Molecules, dynamics, atmospheric structure Biosignature in future 現代の天文学（原稿） Photometric variability Planet Spin/Tilt Surface Composition, Continents, Ocean in future Basic Low-Resolution Spectroscopy Greenbaum+2018 CO? Lacour+2019 Late L Brown Dwarf model well fitted? (covered by clouds) Advanced High-Dispersion Coronagraphy Classical HRS for direct imaging HRS + ExAO + Coronagraph (Snellen+14, Hoeijimakers+18) = High-Dispersion Coronagraphy (Kawahara+14, Snellen+15, Wang+17) REACH on Subaru (Y,J,H) KPIC on Keck (K,L,M) HiRISE on VLT (planned, H,K) Star: planet = 300 : 1 CCF map of water (Hoeijimakers+18) Slit or IFU High-Resolution Single mode Spectrograph Fiber Injection CCF of CO (Snellen+18) REACH collaboration Sebastien Vievard Olivier Guyon Julien Lozi Advanced High-Dispersion Coronagraphy on Subaru REACH on Subaru telescope Extreme AO Coronagraph High-Resolution Spectrograph IRD SCExAO Reference laser Photometric monitoring 2014 idea (Kawahara+2014) 2015-2017 Supported by RESCEU 2019 first light (engneering), open use (since S20B) 2020 Kiban A, first science obs (Aug 1-6 2020) Advanced HDC significantly improves S/N classical AO v.s. ExAO+Coronagraph Comparison of Size on the focal plane Speckle contrast to a host star -1 HR8799 ecd CLASSICAL HRS 10 IRD (MMF) CRIRES+ slit -2 10 0.2’’ 10-3 φ0.48’’ REACH Injection 10-4 e d 10-5 c 0.5” 1” Star-planet separation ExAO + Coronagraph + Small Injection can significantly increase planet signal in R=100,000 spectrum (0.95-1.75 um) Advanced Power of REACH First Engineering run (2019): Spectroscopic binary 1 (SB1) Image of a binary before correction Image of a binary after correction First science run ( this month! ) HR8799e 5.5 hours pilot data. Now processing, we’ll see… Contrast = 3 x 10-4 -> planet : star = 1 : 10 S21A proposal welcome! Short Summary Direct imaging Ground: self-luminous planets so far Pros: cutting-edge technique can be tested by a small group. Cons: It will not reach Earth@solar-type star Toward exo Earth: 30-40 m class telescope will try to detect water/oxygen in terrestrial planets @ late-M Direct imaging from space: not yet. Roman will open, HabEx, LUVIOR Pros: No ExAO needed, it can reach Earth@solar-type star, it can detect oxygen, water. Cons: dev by a small group with try-and-error is almost impossible It’s not clear except for low-res spectroscopy -> Methodology for space DI should be explored more.