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The Earth’s transmission spectrum from lunar eclipse observations:

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Presentation on theme: "The Earth’s transmission spectrum from lunar eclipse observations:"— Presentation transcript:

1 The Earth’s transmission spectrum from lunar eclipse observations:
The pale red dot. E. Palle, M.R. Zapatero-Osorio, R. Barrena, P. Montañes-Rodriguez, E. Martin, A. Garcia-Muñoz

2 What about transiting Earth’s?
But isolating the light from the planet is VERY challenging, what if direct detection is not possible? Atmospheric characterization of Hot Jupiters has already been achieved trough transit spectroscopy What about transiting Earth’s?

3 Poster 36: Montañes-Rodriguez et al.

4 We can observe it during a lunar eclipse
NOT, Visible, μm WHT, Near-IR, μm La Palma, Canaries

5 Lunar eclipse August 16th 2008

6 Umbra Penumbra Brigth Moon

7 Umbra/Bright Umbra Bright

8 Earth’s Transmission Spectrum
The pale red dot μm

9 H2O Ca II O3 O2 Earth’s Transmission Spectrum Visible

10 Fraunhofer lines structure
NO2 ? Ca II Ca II

11 CO2 O2•O2 H2O Earth’s Transmission Spectrum Near-IR ZJ O2 O2•O2 O2•N2

12 Atmospheric Dimers: Van de Waals molecules: Weakly bound complexes
They are present as minor rather than trace species. One likely origin of continuum absorption. Observed on Earth (gas) and Jupiter (gas; (H2)2), Ganymede, Europa and Callisto (condensed), and in the laboratory (gas/condensed). Never on Venus/Mars, where there must be CO2 – X NOT contained in the common spectral libraries Calo and Narcisi (1980)

13 Earth’s Transmission Spectrum
Near-IR HK CH4 H2O CO2 μm

14 How deep we see in the planet atmosphere?
h min ? Are antropogenic signatures visible in the lower layers? Is there a surface signal? Traub, 2009

15 Evolution of the Earth’s Transmission Spectrum during the eclipse

16 Reflection vs Transmission

17 Earth’s Reflectance Spectrum: Earthshine
Same instrumentation only two months apart μm

18 Transmission Spectrum
Reflected spectrum Transmission Spectrum Blue planet? O2 O2•O2 O2•N2 CH4 CO2 CH4 O2•O2 O2 CO2 μm Palle et al, 2009


20 But, how far are we from making the measurements ?
Thus, the transmission spectrum of telluric planets contains more information for the atmospheric characterization than the reflected spectrum. And it is also less technically challenging But, how far are we from making the measurements ?

21 F* F* - F* ( ) + F*( ) T Aa ____ A* Ap*a ______ + Ruido + Ruido

22 Differential transit spectroscopy M star + Earth : 1 (2) measurement
Ss+p / Sp Wavelength (μm)

23 M8 star + 1 Earth ... with the E-ELT
Wavelength (μm) Wavelength (μm) Work in progress ...

24 Still, we must pursue the characterization with direct observations
Exploration of surface features Presence of continents Rotational period Localized surface biomarkers (vegetation) Orbital light curve Ocean glints and polarization effects

25 Conclusions We have obtained the Earths transmission spectra μm First order detection and characterization of the main constituents of the Earth's atmosphere Detection of the Ionosphere : Ca II, ( Mg, Fe, ??) Detection of O2•O2 and O2•N2 interactions Offers more information than the reflectance spectra Using the measured Earth transmission spectrum and several stellar spectra, we compute the probability of characterizing a transiting earth with E-ELT For a Earth in the habitability zone of an M-star, it is possible to detect H2O , O2 , CH4 ,CO2 (= Life) within a few tens of hours of observations.

26 Thank you

27 Thank you


29 The Ring effect Rotational Raman Scattering (RRS)
Early evidence: Sky-scattered Fraunhofer lines were less deep but broader than solar lines Incident exiting λex-Δλ, λex, λex+Δλ frequency redistribution Incident λ + Stokes + Anti-Stokes branches incident photon λex difference/ ratio

30 The Ring effect: Rotational Raman scattering
Vountas et al. (1998) Transmission spectrum Solar spectrum

31 How deep we see in the planet atmosphere?
Evidences? Ref.: Kaltenegger & Traub 2009

32 Nowadays we can monitor night lights, atmospheric changes, plankton blooms, forest health, etc...

33 But, how does our planet look like to ET?

34 When observing an exoplanet, all the light will come from a single point.
We will need a detailed understanding of the “micro-scale” processes to interpret the observed “macro-scale” properties

35 Observing the Earth as a planet (no spatial resolution)
Earth–as-a-point observations with a very remote sensor A compilation of high spatial resolution data into a global spectra or photometry, and modeling Earthshine Observations: The Earthshine is the ghostly glow on the dark side of the Moon

36 The Earthshine on the moon
ES/MS = albedo (+ geometry and moon properties)

37 Leonardo da Vinci, Codex Leicester, 1510

38 Spectral Albedo of the Earth: 2003/11/19
Rayleigh Scattering Chappuis Ozone band B-O2 A-O2 Atmospheric Water vapor Montañés-Rodriguez et al., ApJ, 2006

39 Kaltenegger & Traub 2009 Palle et al, 2009

40 Calo and Narcisi (1980)

41 CoRoT & KEPLER can provide this input
Many other surveys: Plato, TESS, Ground-based searches, ... Terrestrial inner-orbit planets based on their transits: - About planets if most have R ~ 1.0 Re - About 185 planets if most have R ~ 1.3 Re About 640 planets if most have R ~ 2.2 Re (Or possibly some combination of the above) About 12% of the cases with two or more planets per system

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