earth and super-earth atmospheres
DESCRIPTION
Earth and super-Earth Atmospheres. Dimitar Sasselov Harvard-Smithsonian Center for Astrophysics & Harvard Origins of Life Initiative. Outline. The ‘generic’ terrestrial planet. The ‘mini-Neptune’ problem Characterizing geochemical cycles. The “Tree of super-Earths”. ?. Fe -rich mantle. - PowerPoint PPT PresentationTRANSCRIPT
Earth and super-Earth Atmospheres
Dimitar Sasselov
Harvard-Smithsonian Center for Astrophysics
&Harvard Origins of Life
Initiative
Outline
1. The ‘generic’ terrestrial planet
2. The ‘mini-Neptune’ problem
3. Characterizing geochemical cycles
The “Tree of super-Earths”S
uper
-Ear
ths
Mini-Neptunes
OceanPlanets /WaterPlanets
TerrestrialPlanets /Dry, RockyPlanets
Fe -richmantle
?H2O -richmantle
?
?
?
?
(Sasselov, 2008, Nantes)
Earth & super-Earthsvs. gas & ice giants
UV / photo-chemistry
surface /phase transition /boundary layer
atmosphereMatm << Mp
mantle
a well-mixedreservoir
fluxesLoss
Plate tectonics on a 1 MEarth Planet:
QuickTime™ and aSorenson Video 3 decompressorare needed to see this picture.
The “Tree of super-Earths”S
uper
-Ear
ths
Mini-Neptunes
OceanPlanets /WaterPlanets
TerrestrialPlanets /Dry, RockyPlanets
Fe -richmantle
?H2O -richmantle
?
?
?
?
(Sasselov, 2008, Nantes)
Super-Earthsvs.
mini-Neptunes
“Confusion region”
How to distinguish mini-Neptune from super-Earth:
(Mil
ler-
Ric
ci, S
eage
r,S
asse
lov
200
9)
How to distinguish mini-Neptune from super-Earth:
< The 3 types of atmospheres
(Miller-Ricci, Seager,Sasselov 2009)
Zoomed
Super-Earths geochemistry,e.g. the Carbonate-silicate cycle, or Sulfur cycle, etc.
Planets of differentinitial conditionscan be “driven” toa set of geochemicalequilibriaby global geo-cyclesover geologicaltimescales.
Dominant Sulfur outgasing: with JWST
Kaltenegger & Sasselov (2009)
SO2 CO2
No O2 or O3 , but N2 , CO2 , & CH4 .
Conclusions
• Understanding the bulk geochemistry of Earth-like1. planets is an achievable goal,• Use super-Earths as good proxies for Earth,• Much preparatory theory work still needed, e.g.:
• Does the Sulfur (SO2) cycle have a stabilizingfeedback;
• What is the full catalog of possible geo-cycles,incl. on water planets (convecting Ice VII mantle);
• Understand scaling of plate tectonics with mass.
The “Tree of super-Earths”S
uper
-Ear
ths
Mini-Neptunes
OceanPlanets /AquaPlanets
TerrestrialPlanets /Dry, RockyPlanets
Fe -richmantle
?H2O -richmantle
?
?
?
?
KeplerLegacy
TESS &JWSTLegacy
ADDITIONAL SLIDES
Interior Structure: Radius & Composition
Valencia, Sasselov, O’Connell (2007)
Pure Iron super-Earths ? - No.
Marcus, Sasselov,Hernquist, & Stewart (2009)
- giant impacts simulations
70% Fe core:only below4-5 MEarth
Water super-Earths vs. Dry
Zeng & Sasselov (2009)
CoRoT-7b
2
3
1
1 105 20
QuickTime™ and a decompressor
are needed to see this picture.
Front-end
Thermal enclosuresof the spectrograph
HARPS-NEF
The 4.2-m WilliamHerschel telescope,Canary Islands
1m/s in 1h for V=12
QuickTime™ and a decompressor
are needed to see this picture.
Front-end
Thermal enclosuresof the spectrograph
HARPS
The 4.2-m WilliamHerschel telescope,Canary Islands
QuickTime™ and a decompressor
are needed to see this picture.
Thermal enclosuresof the spectrograph
HARPS
A laser comb for HARPS-NEFwavelength calibration
Mode-lockedfemtosecond laser:essentially a 10-15s
‘strobe’
• narrow lines • coherent• equally-spaced• intense• spans optical octave
Li e
t al. 2
00
8
nm
Our red astro-comb in the lab.
Comb lines at the telescope - FLWO, 2008