1. A window to transiting exoplanet characterization.
Observations and modeling of Earth’s transmission spectrum through lunar eclipses:
A window to transiting exoplanet characterization.
E. Palle, M.R. Zapatero, P. Montañes-Rodriguez, R. Barrena, A. Garcia-Muñoz

2. Lunar eclipse
August 16th 2008

3. We observed the Earth transmission spectrum during a lunar eclipse
NOT, Visible, μm
WHT, Near-IR, μm
La Palma, Canaries

4. A penumbral eclipse seen from the Moon
Lunar explorer "KAGUYA" (SELENE) on February 10, 2009
Moon here
JAXA/NHK

5. Umbra
Penumbra
Brigth Moon

6. Umbra/Bright
Umbra
Bright Hα

7. Earth’s Transmission Spectrum
The pale red dot
Palle et al, Nature, 2009

8. Evolution of the Earth’s Transmission Spectrum during the eclipse: ZJ

9. Evolution of the Earth’s Transmission Spectrum during the eclipse: O2 dimer band

10. Modeling efforts: Constructing a true model
Earth – moon distance
∞ = exoplanets
Non-radial symmetry
Direct transmission
Diffraction, refraction
Diffuse light
JAXA/NHK

11. Modeling efforts: The alpha value

12. Transmission models: Rayleigh atmosphere
Garcia-Muñoz et al, in preparation

13. Transmission models: Rayleigh atmosphere
Garcia-Muñoz et al, in preparation
Difference

14. Transmission models: Rayleigh + Clouds (8km) + aerosols (Direct +Diffuse)
Garcia-Muñoz et al, in preparation
Diffuse light insensitive to alpha and dominant at short wavelengths

15. Oxygen complexes in the Earth’s atmosphere: Oxygen dimers
Oxygen at visible wavelengths
Intensity reversal again explained trough diffuse light contribution

16. Oxygen complexes in the Earth’s atmosphere: Oxygen dimers
Oxygen at near-IR wavelengths
O2•O2
O2•N2

17. Earth’s Reflectance Spectrum: Earthshine
NOT, Visible, μm
WHT, Near-IR, μm La Palma, Canaries 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

19. M8 star + 1 Earth ... with the E-ELT
Palle et al, ApJ, submitted
20, 100, 500, 1000 spectra combined - SNR 1000

20. M8 star + 1 Earth ... with the E-ELT
Palle et al, ApJ, submitted
20, 100, 500, 1000 spectra combined - SNR 1000

21. Earth’s transmission spectrum in the mid-IR

22. More Moon Soon ... 21st December 2010: 0.3 – 24 micron VISIR @ VLT3
VLT1
SUBARU
IRTF
Palomar & HST
More Moon Soon ...
21st December 2010: – 24 micron

23. Thank you

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

52. 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
We are developing models to understand the Earth’s transmission spectrum and extend this knowledge to extrasolar transiting rocky planets
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.

53. Thank you

54. 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

55. 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 ?

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

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

58. Detection Perspectives
~5 h
~ 25 h
~ 50 h
~ 150 h
Palle et al, ApJ, submitted

59. Molecular complexes in the Earth’s atmosphere: the 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)
Their total abundance is confined to the lower scale height of the atmosphere.

61. H2O Ca II O3 O2 Earth’s Transmission Spectrum Visible μm

62. Fraunhofer lines structure
NO2 ?
Ca II Hα
Ca II

63. CO2 O2•O2 H2O Earth’s Transmission Spectrum Near-IR ZJ O2 O2•O2 O2•N2 μm

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

65. 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

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

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

68. Garcia-Muñoz et al, in preparation

70. Reflection vs Transmission

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

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

73. 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

74. Kaltenegger & Traub 2009
Palle et al, 2009

75. 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

76. TEST

77. TEST