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Avi M. Mandell NASA GSFC Collaborators :

Spectroscopy of Water and Organics in Exoplanet Atmospheres: First Detections and What the Future Holds. Avi M. Mandell NASA GSFC Collaborators :. Korey Haynes Evan Sinukoff Drake Deming Adam Burrows Nikku Madhusudhan Mark Clampin Don Lindler Natasha Batalha Heather Knutson

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Avi M. Mandell NASA GSFC Collaborators :

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  1. Spectroscopy of Water and Organics in Exoplanet Atmospheres: First Detections and What the Future Holds Avi M. Mandell NASA GSFC Collaborators: Korey Haynes Evan Sinukoff Drake Deming Adam Burrows NikkuMadhusudhan Mark Clampin Don Lindler Natasha Batalha Heather Knutson (others as well)

  2. Henry et al. 1999 • What is a • ExoplanetTransit?

  3. How Do We Learn About the Atmospheresof Transiting Planets? • As starlight passes through the atmosphere of a planet, atoms and molecules absorb at different wavelengths • The more absorption, the deeper the depth of the transit… but absorption depends on abundance, temperature, optical depth • Exoplanet transits provide the opportunity to probe the absorption in a planet’s atmosphere Planet Cross-Section

  4. HST / WFC3 Grism Spectroscopy: Resolving Molecular Absorption • Wavelength range (1.1 – 1.7 μm) samples water bands at 1.15 and 1.4 μm as well as several hydrocarbons and continuum regions on either side • Can answer major questions about temperature and chemistry • But at LOW resolution over a NARROW bandpass, degeneracies still remain!

  5. Deming et al.Program (Cycles 18 & 19) • Large collaboration focused on hot giant exoplanets • Sample of 16 objects • A number of planets may have upper-atmosphere temperature inversions or high C/O ratios • We started with several interesting (and outlying) cases: • WASP-12: Very hot, first possible carbon-rich exoplanet, but results now in dispute • WASP-17:Ultra-low density, retrograde orbit • WASP-19: Shortest-period planet known (P ~ 19 hr) but no temperature inversion • WASP-33: Very hot and massive, orbiting an A-type star, possibly carbon-rich List of Observed Planets CoRoT-1 b CoRoT-2 b HAT-P-7 b HAT-P-12 b HAT-P-13 b HD189733 b HD209458 b TrES-2 b TrES-3 b TrES-4 b WASP-4 b WASP-12 b WASP-17 b WASP-18 b WASP-19 b XO-1 b WASP-33 b WASP-12 WASP-33 WASP-19 WASP-4 WASP-17 Transits Eclipses

  6. Transit Spectra Analysis: SystematicsRemoval Through Self-Calibration We used the divide-ootmethod (Berta et al. 2012) to fit the band-integrated light curve We subtracted the model from the raw light curve to obtain the residual systematic variation; additional trends due to spectral drift were also measured We created a model for each wavelength bin, with a scaling parameter for each possible systematic trend in the data and an overall visit-long slope WASP-12 WASP-17 WASP-17 WASP-19

  7. PrimaryResult: Amplitude of water absorption band islower than expected (based on previous Spitzer obs.) • Due to either: • Anunexplained haze layer that increases the continuum opacity below a certain altitude • Less water due to non-solar abundances (T ~ 2900K) (T ~ 2000K) (T ~ 2500K)

  8. Primary Result: Amplitude of water absorption band is lower than expected (based on previous Spitzer obs.) • Due to either: • Anunexplained haze layer that increases the continuum opacity below a certain altitude • Less water due to non-solar abundances (T ~ 2000K) • A • 2 • Cooler planets seem to show well-defined spectral features, while hotter planets are ambiguous… • NEED MORE PLANETS and MORE SPECTRAL COVERAGE (T ~ 1800K) (T ~ 1700K)

  9. Eclipse Spectra Analysis: • We again used the divide-ootmethod to fit the band-integrated light curve, • WASP-33 presents additional complications due to Delta Scuti oscillations in the parent star • Band-integrated eclipse depths are much more uncertain than the transit measurements due to the low eclipse-to-noise ratio • WASP-4 is especially problematic due to very little temporal coverage during eclipse

  10. WASP-4 PreliminaryResult: WFC3 data appear to match up with the thermal-inversionatmosphere model from Beerer et al. 2011; however, a blackbody seems to be an even better fit (T ~ 2900K) • The spectrum seems to show a slight peak at 1.4 microns, indicative of a possible strong inversion • However, this model does not match the Spitzer data well • A blackbody with Tplan = 2200 K provides an excellent fit to all existing data Tplan~ 2200K (T ~ 2500K)

  11. WASP-12 Preliminary Result: WFC3 data appear to support a carbon-rich model, showing no sign of the expected deep absorption band. • However, as noted in Crossfield et al. 2012, correcting the Spitzer data for the nearby companions leads to an isothermal interpretation

  12. WASP-33 Preliminary Result: WFC3 data strongly support a model with no thermal inversion, and models that are carbon-rich fit better • Further modeling is required to determine whether we can break degeneracies between temperature and composition

  13. The Future of Space-Based Characterization: JWST (of course) • JWST will provide sensitivity gains of more than an order of magnitude • We are preparing to adapt our WFC3 analysis pipeline to JWST, based on current instrument models by M. Clampin & D. Lindler • For hot Jupiters, the real test lies in which instruments and filters to use in order to MOST EFFICIENTLY constrain the atmospheric parameters JWST Wavelength Coverage & Resolution JWST/NIRSPEC Simulations CO2 Abs. H2O Abs. Simulated Hot Super-Earth (Teq ~ 500K) around an M-star at 30 pc H2O Abs. CH4 H2O C2H2 CO Simulated Habitable Super-Earth (Teq ~ 300K) around an M-star at 20 pc HCN CH4 CO CO2 H2O CO H2O Deming et al. 2009

  14. JWST NIRSPEC Simulator • Begins with In-transit and Out-of-transit model • Maps onto pixel space • Convolves with PSF, multiplies by PRF • Add noise sources • Zodiacal and stray light • Flat field errors • Poisson and read noise • Spacecraft jitter and drift 14 pc, V = 15 4.5 pc M-type host star 4 MEarth planet 25 transits H2O & CH4 Images from Don Lindler, results from Batalha et al. (JWST White Paper)

  15. Pre-JWST Characterization: Low-Cost NIR Spectroscopy from a Balloon? • Ultra-long duration (ULD) balloon platforms offer the potential for long-term, stable monitoring of transiting planets above almost all telluric contamination • As low as 1 - 2%of an equally-capable space mission • Test flight using the Wallops Arc Second Pointer (WASP) gondola system planned for September 2014 • Use of existing and off-the-shelf parts will allow us to benchmark the current limits for stability and thermal control

  16. Conclusions • The WFC3 instrument on HST has now been validated as a reliable platform for high-precision exoplanet transit observations • Observations of Hot Jupiters are revealing unexpected mysteries • Hazes and/or aerosols may be common, but vary with planet properties • Thermal emission measurements suggest blackbody emission at NIR wavelengths may be ubiquitous; unclear if this is due to thermal or compositional factors, and why it appears so uniform • Increased S/N and larger wavelength coverage (combining Spitzer, HST and ground) will be necessary to grapple with these questions • JWST will clearly change the landscape dramatically, but observing time will be precious, so we must pre-select targets for follow-up

  17. Questions?

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