jonathan fortney university of california, santa cruz
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Jonathan FortneyUniversity of California, Santa Cruz
Spectroscopy of Giant Planets
JWST Transit Planets Meeting
PPVI Review:Madhusudhan,Knutson,Fortney, & BarmanarXiv:1402.1169
We’re 40-45 years behind work in the Solar System
Lee et al. (2012)
Jupiter
Gillett, Low, & Stein (1969)
• CH4 dominant mid IR absorber• Temperature inversion from 7.8 m
CH4 band• Bright at 5 m – high Tbright
The Past Ten Years of Atmospheric Characterization
• We’ve been trying very hard to make progress using instruments that were not designed for our uses
• We’ve gathered somewhat imprecise broadband data for dozen of planets
Line et al. (2013)
High S/N data over a broad wavelength range fundamentally changes the kinds of questions we can ask and answer
Line et al.(2013)
We are not merely tying up loose ends – it is not even close to that!
Is atmospheric metal-enrichment a hallmark of giant planets?
How does this change with: Planet mass Stellar type Migration history
Do giant planets share the abundance ratios of their parent star?
Jupiter is quasi-consistent with 2-4x solar How important is disk condensation (snow
lines) in leading to deviations in abundances?
Giant Planet Spectroscopy
How significantly do atmospheres deviate from radiative equilibrium (energy sources and sinks)How is day-night temperature homogenization affected by:
Incident flux Surface gravity Atmospheric metallicity Rotation rate
What is the role of cloud opacity? Does it effect emitted spectra as well as transit
spectra? Can we figure out what the cloud compositions are?
Chemistry Role of deviations from equilibrium chemistry Homogenization due to vertical and or horizontal mixing
Atmospheric Physics and Chemistry
• We’d like to know the abundances of these molecules within a factor of ~5-10• Would allow connection to planet formation
Shabram et al. (2011)
Broad JWST coverage over molecules of interest
Shabram et al. (2011)
Broad JWST coverage over molecules of interest from a C/O ratio or photochemical perspective
The Unknown Unknowns: Our imperfect understanding of these atmospheres, in the absence of spectral data
• Phosphorus compounds?• Sulfur compounds?• I don’t know (that’s why
they’re called unknown unknowns)
Excellent Recent Progress with HST WFC3
Deming et al. (2013)Kreidberg, Line, Stevenson, Bean, others, et al. (in prep)
WASP-43b
Transmission Emission
Also: Precision of ~20-30 ppm for transmission spectra: Kreidberg et al., Knutson et al.
Model Atmospheres are Rounding into Shape
FortneyBurrows
WASP-19b Huitson et al. (2013)
DemingFortney
WASP-19b
A major concern of mine over the past 5 years has been the lack of comparisons between modeling groups
This is still imperfect but has gotten a lot better
Some groups have honed their R-T, chemistry, and clouds on brown dwarf spectra across a wide Teff range
• 1D techniques, including retrieval techniques, aim to understand hemispheric average conditions
• Patchy clouds on planets may be a problem?• Non uniform transiting planet day sides may be a bigger problem?
HD 189733b, Showman et al. (2009)
HD 189733b, Dobbs-Dixon et al. (2013)DayNight
Fundamental Assumption
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