Download Atmospheres of TrES-1 and HD209458b (Part 2)

Spectroscopy of Giant Planets
Jonathan Fortney
University of California, Santa Cruz
PPVI Review:
Madhusudhan,
Knutson,
Fortney, &
Barman
arXiv:1402.1169
JWST Transit Planets Meeting
We’re 40-45 years behind
work in the Solar System
Jupiter
Gillett, Low, & Stein (1969)
• CH4 dominant mid IR absorber
• Temperature inversion from 7.8 mm
CH4 band
• Bright at 5 mm – high Tbright
Lee et al. (2012)
The Past Ten Years of Atmospheric Characterization
Line et al. (2013)
• 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
High S/N data over a broad wavelength range fundamentally
changes the kinds of questions we can ask and answer
Line et al.
(2013)
Giant Planet Spectroscopy
 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?
Atmospheric Physics and Chemistry
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
Broad JWST coverage over molecules of interest
Shabram et al. (2011)
• We’d like to know the abundances of these molecules within a factor of ~5-10
• Would allow connection to planet formation
Broad JWST coverage over molecules of interest
from a C/O ratio or photochemical perspective
Shabram et al. (2011)
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
Transmission
Emission
WASP-43b
Kreidberg, Line, Stevenson, Bean, others, et al. (in prep)
Deming et al. (2013)
Also: Precision of ~20-30 ppm for transmission spectra: Kreidberg et al., Knutson et al.
Model Atmospheres are Rounding into Shape
WASP-19b
Fortney
Burrows
WASP-19b
Deming
Fortney
Huitson et al. (2013)
 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
Fundamental Assumption
Day
Night
HD 189733b, Showman et al. (2009)
• 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, Dobbs-Dixon et al. (2013)