jonathan fortney university of california, santa cruz

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