Jakša Cvitani ć , Ali Lazrak, Lionel Martellini and Fernando Zapatero
The Earths transmission spectrum from lunar eclipse observations: The pale red dot. E. Palle, M.R....
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Transcript of The Earths transmission spectrum from lunar eclipse observations: The pale red dot. E. Palle, M.R....
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
But isolating the light from the planet is VERY challenging,what if direct detection is not possible?
What about transiting Earth’s?
Atmospheric characterization of Hot Jupiters has already been achieved trough transit spectroscopy
Poster 36: Montañes-Rodriguez et al.
We can observe it during a lunar eclipse
NOT, Visible, 0.4-1 μmWHT, Near-IR, 0.9-2.5 μmLa Palma, Canaries
Lunar eclipse August 16th 2008
Umbra
Penumbra
Brigth Moon
Umbra
Umbra/Bright
Bright
Hα
0.5 1.0 1.5 2.0 2.5
Earth’s Transmission Spectrum
The pale red dot
μm
O2
O3
Ca II
H2O
Earth’s Transmission SpectrumVisible
0.4 0.5 0.6 0.7 0.8 0.9 μm
O4Ca II
Ca II
Hα
NO2 ?
Fraunhofer lines structure
CO2
H2O
O2•O2
1.0 1.25 1.5
O2
O2•O2
O2•N2
Earth’s Transmission SpectrumNear-IR ZJ
μm
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; (H
2)
2), Ganymede, Europa and Callisto
(condensed), and in the laboratory (gas/condensed).
• Never on Venus/Mars, where there must be CO
2 – X
• NOT contained in the common spectral libraries
Calo and Narcisi (1980)
CH4
CO2
H2O
1.5 2.0 2.5
Earth’s Transmission SpectrumNear-IR HK
μm
How deep we see in the planet atmosphere?
h
T(h, )
Traub, 2009
h min ?
• Are antropogenic signatures visible in the lower layers?
• Is there a surface signal?
Evolution of the Earth’s Transmission Spectrum during the eclipse
Reflection vs Transmission
Earth’s Reflectance Spectrum: Earthshine
Same instrumentation only two months apart
0.5 1.0 1.5 2.0 2.5μm
0.5 1.0 1.5 2.0 2.5
Reflected spectrum Transmission Spectrum
CO2 CH4
CH4
O2 CO2
Blue planet?
O2
O2•O2
O2•N2
O2•O2
Palle et al, 2009μm
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 ?
F*
F* - F* ( ) + F*( ) T Aa
____
A*
Ap*a
______
A*
+ Ruido
+ Ruido
Wavelength (μm)
Differential transit spectroscopy M star + Earth : 1 (2) measurement
Ss+p / Sp
M8 star + 1 Earth ... with the E-ELT
~5 h
~ 150 h~ 50 h
~ 25 h
Wavelength (μm) Wavelength (μm)
Work in progress ...
Still, we must pursue the characterization with direct
observations
Exploration of surface featuresPresence of continentsRotational periodLocalized surface biomarkers (vegetation)
Orbital light curve Ocean glints and polarization effects
Conclusions
We have obtained the Earths transmission spectra 0.4-2.5 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.
Thank you