Exo-Planetary atmospheres and host stars. G. Micela INAF Osservatorio Astronomico di Palermo

Transcription

1 Exo-Planetary atmospheres and host stars G. Micela INAF Osservatorio Astronomico di Palermo

2 Thousands of exoplanets discovered. Huge range of masses, sizes and orbits. Jupiters Neptunes Super-Earths Earths

3 Frequency Structure Atmosphere Role of the host star Role of the environment

4 IMPLICATION OF ATMOSPHERIC STUDIES Structure Formation Evolution primary & secondary atmospheres Habitability Climate

5 SEVERAL PROCESSES DETERMINE THE ATMOSPHERE PROPERTIES

6 HABITABILITY?

7 DIFFICULT TO DEFINE: ATMOSPHERE ALONE IS NOT SUFFICIENT Planets with syncronized rotation may be habitable? Leconte et al 2015

8 THE SOLAR SYSTEM AT 10 PC Star STAR Fp/F* = p Rp 2 /a 2 Fp/F* = Tp/T* Rp 2 /R* 2 = (R*/2a) 1/2 [f(1-a)] 1/4 Hot Jupiters V M M V E E J J

9 THE SOLAR SYSTEM AT 10 PC Star STAR Fp/F* = p Rp 2 /a 2 Fp/F* = Tp/T* Rp 2 /R* 2 = (R*/2a) 1/2 [f(1-a)] 1/4 Hot Jupiters HOT JUPITER V M M V E E J J

10 Signal dominated by the star Very high SNR Very good control of systematics Appropriate observational strategy Direct detections Transiting planets Radial velocity monitoring

11 OBSERVING ATMOSPHERES Direct Imaging Wide-Separations asin(i), Flux pl (λ) Composition Clouds/Hazes Temperatures Dynamics Transits/occultations Close-In Planets R pl (λ), i, P, a, Flux pl (λ,φ) Composition Clouds/Hazes Thermal profile Escape Dynamics, Winds Dynamics Photochemistry Radial velocity Bright Targets Composition Stratospheres Dynamics, Winds

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13 DIRECT IMAGING Adaptive optics & coronography (infrared) Large telescopes (VLT, KECK, ELT, ) Direct spectroscopy of wide-orbit exoplanets Young orbits formation and early evolution

14 SOME EXAMPLES OF DIRECT IMAGING

15 THE PLANETARY SYSTEM AROUND HR 8799 C D Konopacki et al. 2013

16 STAR AND PLANET EVOLUTION STARS Brown dwarfs Planets Burrows et al. 1997

17 STAR AND PLANET EVOLUTION Young planets STARS Brown dwarfs Planets Burrows et al. 1997

18 Bowler et al. 2016

19 WIDE-ORBIT PLANETS ARE RARE

20 SENSITIVITY FOR IMAGING OF PLANET AROUND CLASSES OF YOUNG STARS

21 TRANSIT & ECLIPSE SPECTROSCOPY Aiming at ~10-4 stellar flux at multiple wavelengths through stable instrument, external calibration & postprocessing analysis Close-in planets

22 Day side spectra - eclipse Reflected radiation - ~ Visible -NIR Thermal emission - IR T < 1200K Reflected emission > Thermal emission 1. Albedo 2. T-p profile 3. Chemistry Night side spectra primary transit Transmitted spectrum - IR 1. ~Upper atmosphere 2. Chemical composition 3. ~Temperature

23 HOW DO PLANETS FORM? Measure relative elemental composition Models of Turrini, et al. (2015).

24 PROBING ELEMENTAL COMPOSITION ammonia methane water (O,C,N,S..) in hot, gaseous exoplanets We can probe elemental composition for hot gaseous planets Water never condenses at T eq > 500 K Most of the other main reservoirs of oxygen, carbon, and nitrogen (e.g. CO, CH 4, CO 2, NH 3, N 2 ) condense at even lower temperatures The advantage of hot planets

25 PLANETARY ENERGY DISTRIBUTION HAT-P-7b (T p 2166 K) CoRoT-1b (T p 1850 K) HD b (T p 1408 K) HD b (T p 1168 K) GJ1214 (T p 545 K) GJ1214 (a 0.3, T p 512 K) Radiance (W sr 1 m Wavelength ( m)

26 KEY MOLECULES ABSORBING IN IR ExoMol

27 CHEMICAL COMPOSITION TiO/VO? H 2 O Evans et al. (2016) WASP-121b Ultra-hot Exoplanet (2700 K) 1 Transit with WFC3

28 SEVERAL OPEN ISSUES Thermal inversion? WASP-33b the best case Problems with systematics stellar variability & cross-calibration between different instruments ASTROBIOLOGY, Veli Lošinj, Croatia, 25th Haynes et al. (2015)

29 ANOTHER ULTRA-COOL JUPITER Water VO?? Inverted T-P profile Emission spectrum Evans et al 2017

30 CH 4 (HD189733) Swain et al. (2008) However possible systematics still uncorrected! Work in progress: future instruments Swain et al. (2008)

31 HST+Spitzer Large variety T eq =950/2500K Na, K, H 2 O Haze & Clouds Strong aerosols Evans et al. 2016

32 NEPTUNIANS & SUPER-EARTHS Water (several features) GJ 1214b Clouds can cover any features Wakerford et al Kreidberg et al HD 97658b: More clouds, hazes? 55 Cnc e: H-rich atmosphere? Varley et al Knutson et al. 2014

33 THE JWST OPPORTUNITY HST + JWST, Batalha et al Simulation of Emission from WASP- 33b with JWST Cross-calibration? Stellar variability? Cross-calibration?

34 THERMAL EMISSION NIRSpec & MIRI simulations of a giant planet Transit Spectrum of Habitable Ocean Planet

35 2600 HOURS (6% OF 5 YEARS) Goal Targets Visits Hours Assess strategies Jupiter Eclipse Survey Jupiter Transit Survey Cool Atmospheres Neptune Atmospheres Super-Earth Atmospheres Phase curves, Weather, Assumes an average of 5 hours / visit

36 ARIEL M4 ESA mission (selection Oct/Nov 2017) 1-m telescope, spectroscopy from VIS to IR - Simultaneous coverage micron (R =1 to 300) Payload consortium: 11 ESA countries Atmospheres of ~1000 exoplanets (rocky + gaseous), mainly transits and eclipse Individual planet Chemical composition Atmospheric circulation + cloud pattern Equilibrium or non-equilibrium chemistry? Impact with stellar environment Coupling interior-atmosphere Impact of stellar environment & system history Large population of diverse planets Chemical diversity Correlation clouds temperature-stellar-type How fast atmospheres change through time? Correlation elemental composition planet provenance Coupling atmosphere-interior through time Transition between terrestrial planets and sub-neptunes ARIEL ESA M4 Paris presentation

37 LARGE POPULATION OF WARM/HOT PLANETS SELECTED OUT OF 10,000 PLANETS OPTIMAL FOR CHEMICAL OBSERVATIONS Planets around F stars N. planets Parameter space to be sounded: Planet size, Temperature, Density; Stellar type, Metallicity R Earth T (K) The sample should have ~ 1000 planets ARIEL ESA M4 Paris presentation

38 RADIAL VELOCITY MONITORING High-Dispersion Spectroscopy (λ/δλ 100,000) Large effective area Molecular Bands are resolved in tens of individual lines Strong Doppler effects due to orbital motion of the planet (up to >150 km/sec) Moving planet lines can be distinguished from stationary telluric & stellar lines

39 CHALLENGES FOR GROUND-BASED OBSERVATIONS OF PLANETARY ATMOSPHERES Measure < variations in flux as function of λ over 1-5 hour time scales Earth Atmosphere: Variations in turbulence / seeing Variations in absorption & scattering Variations in thermal sky emission Instrumental: Variations in gravity vector or field rotation Variations in thermal behaviour

40 OBSERVING STRATEGY: ALREADY TESTED CO in transmission in HD209458b (Snellen et al. Nature 2010) Reveals planet orbital velocity Solves for masses of both planet and star Evidence for blueshift - high altitude winds? - marginal 2σ suggestion Soon GIARPS@TNG

41 TELESCOPIO NAZIONALE GALILEO (CANARIAN Common feeding for HARPS-N and GIANO high resolution VIS-NIR spectra + high precision radial velocities ISLANDS) H 2 O detection in HD18973 with GIANO Simultaneous use of: HARPS-N (0.38 µm < λ< 0.69 µm) GIANO (0.95 µm < λ < 2.45 µm) already on duty at TNG Volume mixing ratio H 2 O 10-4 Brogi et al in prep.

42 - 2 ND GENERATION ELT INSTRUMENT ELT: 39 m Large Area! Orbital inclinations and masses of >100 non-transiting planets Detection of the individual lines (instead of cross-correlation) T/P profile; unambigous detections of inversion layers Line broadening: planet rotation and circulation Molecular spectra (CO,CO 2,H 2 O,CH 4 ) as function of orbital phase photochemistry, T/P vs. longitude Evolution of planetary atmospheres

43 : The most ambitious HIRES Science Case: Characterizing twin-earths O 2 in transmission is possible Snellen et al. 2013

44 A different way to look Planets may appear different if observed in different bands Which information from high energy band?

45 THE TRANSIT OF VENUS: PROBING THE HIGH PLANET ATMOSPHERE measuring the radius in different bands from optical to X-rays Reale et al Nature comm.

46 THE OBSERVATIONS Solar Dynamics Observatory (SDO) Atmospheric Imaging Assembly (AIA, pixels size arcsec) Hinode 4500 A (78 images) 1700A (114 images) 1600 A (124 images) 335 A (166 images) 304 A (118 images) 211 A (117 images) 193 A (119 images) 171 A (120 images) X-Ray Telescope (XRT): (~10 A, pixel size arcsec) (102 images) AIA 4500A AIA 335A XRT

47 Start: 5 June 2012 End: 6 June :25 UTC 04:16 UTC 4500 Ang 335 Ang

48 VENUS RADIUS VS WAVELENGTH: COMPARISON WITH MODELS (FOX 2011) SZA 95 o SZA 90 o

49 EUV VS OPTICAL RADIUS

50 Transits in X-rays of exoplanets to measure upper atmospheric layers A pilot study for Athena? RESULTS High energy photons are absorbed at larger altitude where EUV an X-rays photoionize molecules Probe altitude of the densest ion layers of Venus s ionosphere (CO 2 and CO), Probe of Venus atmosphere models at the terminator

51 PLANETS MAY AFFECT THE STAR!

52 STAR-PLANET MAGNETIC INTERACTIONS Star-Planet Magnetic Interactions Stellar (dynamo-generated) magnetic field are expected to interact with the magnetospheres of close-in Jupitermass planets Magnetic stresses and reconnection events energy release, heating of stellar and planetary atmospheres, enhanced chromospheric and coronal radiation Detection of these effects characterization of planetary magnetospheres feedback effects, e.g. heating and evaporation of planetary atmospheres 29th

53 XMM-NEWTON X-RAY OBSERVATIONS OF HD (Pillitteri et al. 2010, 2011, 2014) Strong variability after the planetary eclipse (phase 0.5) Analysis of 2012 X-ray flare suggests long magnetic structure, G magnetic field, SAILING THROUGH and dense THE WONDERS plasma OF

54 HST/COS FUV OBSERVATIONS OF HD Pillitteri et al., 2015 ApJ 5 HST orbits, COS spectra A Strong FUV variability after phase 0.5 First event: red-shifted lines, up to km/s Second event: lines blue-shifted of km/s

55 MHD simulations by Matsakos et al. (2015) Accretion of material from the planet, Strong planetary outflow Active spot on stellar surface co-moving with the planet Phased variability MODELING OF HD SPI: THE PLANET SPOON-FEEDING ITS STAR Pillitteri et al., 2015 ApJ in press, arxiv:

56 NEW TEST CASE: HD 17156B, HOT JUPITER IN HIGHLY ECCENTRIC ORBIT Host star Sp G0, V=8.2, M * = M R * = R Age= Gyr Transiting planet M p = M J, R p = M J (Nutzman et al. 2011), Orbit P orb = 21.2 d, e = , a = AU i =

57 HD 17156b orbit Periastron 7 hr after transit XMM obs on Sep 4: 5 days after periastron XMM obs on Sep 20 started 9 h after periastron, duration 10h 29th

58 SOFT X-RAY IMAGES 29th

59 SOFT X-RAY IMAGES X-ray detection (6.6 in the kev band) ONLY at periastron! (Maggio et al ApJ) 29th

60 SOFT X-RAY IMAGES Result supported by Ca I H&K chromospheric emission observed by HARPS-N (Maggio et al ApJ) 29th