Transcript Spectra Lisa - Harvard-Smithsonian Center for Astrophysics

Assembling the puzzle
From Earths to Super-Earths
Hitran to the rescue...
“Good planets are hard to find”
Bracewell
Lisa Kaltenegger
Harvard-Smithsonian Center for Astrophysics
HITRAN Conf, June 22th 2008 1
Planets...
The story so far...
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New worlds in our sky... 300+
shadows of weird worlds...
What can we tell?
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The KEY...
Fortney, 2007
Sasselov 2007
Transiting planets
Torres 2008
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Weather forecast on Giant exoplanets?
Atmosphere by transits... HD189733b
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Tinetti et al 2007
WHY ?
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The Pale Blue Dot
Voyager image,
400 billion km away
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Earth IR-emission
TES data; Christensen 2004
Kaltenegger, Traub, Jucks 2007 (ApJ)
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Line of Evidence
LIFE ?
What biota?
ATMOSPHERE
What chemistry?
What star ? HZ ?
INTERIOR
Plate tectonics?
Ocean/land?
WHAT KIND
Density ?
(radius/mass)
FORMATION
Formation Models
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Line of Evidence
LIFE ?
SPECTRAL
FINGERPRINT
ATMOSPHERE
INTERIOR
FIND
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OUTLINE CODES
Planet interior & outgassing
add
• Climate (Kasting, Segura, Pavlov) Cloud physics (CO2 & H2O)
add
• Photochemistry (Segura, Kasting)
• Radiative Transfer (Traub, Jucks)
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Kaltenegger et al 2007
Signs Of Life On An Earth-like Planet
Needed
for life
observed
Plant
life
Plant
product
Primordial;
& bacteria
product
Bacteria
Vegetation
Ozone Water Carbon Methane
dioxide
Oxygen
Nitrous
oxide
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Selsis 2007
Spectral features IR & Is there Take out ?
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Traub & Jucks, AGU, 2002; Des Marais et al. 2002, Selsis 2003, Kaltenegger 2007
Atmospheric
escape
photochemistry
Biological processing
Geochemical recycling
Outgassing
e. g. carbonate silicate cycle
Early or continuous
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The Test...The possibilities...Characterizing planets
Selsis (data Kasting et al 93)
Update Kaltenegger & Segura (prep)
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Habitable Zone... Goldilocks Zone
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Selsis, Kasting et al 2007; Kaltenegger & Selsis 2007
CIS for Exoplanets: Spectral Fingerprints
TPF-C
New World
Finder
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Paillet et al., in prep
Earth part of the puzzle...
& a universe full of possibilities
Sontin et20al 2007
Leger et al 2004
How to make water from
a H2-rich atmosphere ?
Reduction of Fe-bearing silicates
by H2 (Sasaki, 1990)
For fO2 ≤ core formation
H20/H2 ~ 0.1
(Solar nebula : 6 x 10-4 Delivery?)
H2O vapor promotes greenhouse:
Earth’s temp. as high as 4800 K
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Earth Evolution over geological time
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Kaltenegger et al 2007 ApJ
Goldilocks Zone
Gl 581c... HOT, Gl581d COLD
Continuous habitable zone
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Selsis et al 2007, Kaltenegger et al 2008, Seager et al 2008, Miller-Ricci et al 2008,...
Super Earth around M star 3400K
Tidally locked planet
1: day (60%) night side (40%)
2: day (75%) night side (25%)
3: day (85%) night side (15%)
Kaltenegger et al 2008 (in prep)
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Super Earth around M star 3400K
Tidally locked planet (rapidely rotating planet comparison line (shown in grey))
•
Scenario 3: high heat transport from day (85%) to night side (15%)
Kaltenegger et al 2008 (in prep)
CO2
O3
CH4
H2O
H2O
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Transits... Pushing the limits
Radius +/- ~ 0.06%
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Kaltenegger, Traub, Jucks 2008 (sub)
Transits... Detecting habitable atmospheres
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Kaltenegger, Traub, Jucks 2008 (sub)
Hitran Shopping list
•
•
•
•
Near-IR lines (CH4)
Line profile (especially wings - Transits)
Self broadening... Line broadening
High atm pressure (< 3 bar)
– (= high gravity on Super-Earths)
• Transits probe upper Earth atmosphere mainly
• Warming and cooling of atmosphere
– e.g. dense and early Earth atmospheres
–…
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SUPER EARTHS...
opportunity & challenge
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Habitabitity of Super Earths Gl581d
Gl 581d: Earth Amtosphere, 2.63 bar, 1.8x Earth gravity. M star 3200K
Scenario 1: no heat transfer day & night side (freeze out on dark side)
Scenario 2: Planet rapidely rotating like Earth (same temperature day and night side)
Scenario 3: Low heat transfer between day (75%) & night side (25%), no freeze out
Kaltenegger et al. 2008 (in prep)
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