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ASTROCHEMISTRY APPLIED TO PLANETS: COSMIC-RAY IONIZATION AND HAZES ON HOT-JUPITERS Paul B Rimmer (University of St Andrews) Catherine Walsh (QUB, Leiden Observatory) Christiane Helling (University of St Andrews) Thursday, 18 April 13

ASTROCHEMISTRY APPLIED TO PLANETS: COSMIC-RAY …conference.astro.ufl.edu/STARSTOLIFE/science_final/talks/... · 2013-04-29 · ASTROCHEMISTRY AND ATMOSPHERIC CHEMISTRY • Astrochemistry

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Page 1: ASTROCHEMISTRY APPLIED TO PLANETS: COSMIC-RAY …conference.astro.ufl.edu/STARSTOLIFE/science_final/talks/... · 2013-04-29 · ASTROCHEMISTRY AND ATMOSPHERIC CHEMISTRY • Astrochemistry

ASTROCHEMISTRY APPLIED TO PLANETS:

COSMIC-RAY IONIZATION AND HAZES ON HOT-JUPITERS

Paul B Rimmer (University of St Andrews)Catherine Walsh (QUB, Leiden Observatory)Christiane Helling (University of St Andrews)

Thursday, 18 April 13

Page 2: ASTROCHEMISTRY APPLIED TO PLANETS: COSMIC-RAY …conference.astro.ufl.edu/STARSTOLIFE/science_final/talks/... · 2013-04-29 · ASTROCHEMISTRY AND ATMOSPHERIC CHEMISTRY • Astrochemistry

ASTROCHEMISTRY AND ATMOSPHERIC CHEMISTRY

• Astrochemistry

• Hydrogen dominated

• Gas and surface chemistry

• 10 - 1000 K, 100 - 1010 cm-3

• Dominated by ion-neutral chemistry

• Lots of radicals, unsaturated carbon chains

• Atmospheric Chemistry

• Hydrogen dominated, or not

• Possible surface chemistry?

• 500 - 3000 K, 108 - 1019 cm-3

• Three-body, neutral-neutral reactions

• Carbons are saturated, aromatic

Thursday, 18 April 13

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ASTROCHEMISTRY AND ATMOSPHERIC CHEMISTRY

•Astrochemistry •Atmospheric Chemistry

Bean et al. (2010)Bergin et al. (2010)Thursday, 18 April 13

Page 4: ASTROCHEMISTRY APPLIED TO PLANETS: COSMIC-RAY …conference.astro.ufl.edu/STARSTOLIFE/science_final/talks/... · 2013-04-29 · ASTROCHEMISTRY AND ATMOSPHERIC CHEMISTRY • Astrochemistry

ASTROCHEMISTRY AND ATMOSPHERIC CHEMISTRY

•Astrochemistry

•Complex species have N > 6

•Things like CH2OHCHO

•Atmospheric Chemistry

•Complex species have more than one carbon.

•C2H2, C2H4, anything with three carbons or more!

Thursday, 18 April 13

Page 5: ASTROCHEMISTRY APPLIED TO PLANETS: COSMIC-RAY …conference.astro.ufl.edu/STARSTOLIFE/science_final/talks/... · 2013-04-29 · ASTROCHEMISTRY AND ATMOSPHERIC CHEMISTRY • Astrochemistry

WHY APPLY ASTROCHEMISTRY TO ATMOSPHERES?

Thursday, 18 April 13

Page 6: ASTROCHEMISTRY APPLIED TO PLANETS: COSMIC-RAY …conference.astro.ufl.edu/STARSTOLIFE/science_final/talks/... · 2013-04-29 · ASTROCHEMISTRY AND ATMOSPHERIC CHEMISTRY • Astrochemistry

THE HAZY CASE OF HD 189733 b

• Pont & Sing observed a haze in the upper atmosphere of HD 189733 b.

• Equilibrium gas-phase chemistry can’t account for hazes.

• Non-equilibrium dust formation (nucleation + growth) can, but not that high up in the atmosphere.

• Where is the haze coming from, and what is it made of?

C. Carreau (ESA)

Thursday, 18 April 13

Page 7: ASTROCHEMISTRY APPLIED TO PLANETS: COSMIC-RAY …conference.astro.ufl.edu/STARSTOLIFE/science_final/talks/... · 2013-04-29 · ASTROCHEMISTRY AND ATMOSPHERIC CHEMISTRY • Astrochemistry

PARTS OF A GIANT GAS PLANET’S ATMOSPHERE

Thermosphere

Stratosphere

Troposphere

Thursday, 18 April 13

Page 8: ASTROCHEMISTRY APPLIED TO PLANETS: COSMIC-RAY …conference.astro.ufl.edu/STARSTOLIFE/science_final/talks/... · 2013-04-29 · ASTROCHEMISTRY AND ATMOSPHERIC CHEMISTRY • Astrochemistry

JUPITER

Thursday, 18 April 13

Page 9: ASTROCHEMISTRY APPLIED TO PLANETS: COSMIC-RAY …conference.astro.ufl.edu/STARSTOLIFE/science_final/talks/... · 2013-04-29 · ASTROCHEMISTRY AND ATMOSPHERIC CHEMISTRY • Astrochemistry

HD 209458 b

European Space Agency and Alfred Vidal-Madjar

Thursday, 18 April 13

Page 10: ASTROCHEMISTRY APPLIED TO PLANETS: COSMIC-RAY …conference.astro.ufl.edu/STARSTOLIFE/science_final/talks/... · 2013-04-29 · ASTROCHEMISTRY AND ATMOSPHERIC CHEMISTRY • Astrochemistry

NON-EQULIBRIUM CHEMISTRY:WHAT CAUSES IT?

• Effects within the Atmosphere

• Large-scale motion (Convection)

• Small-scale motion (Turbulence)

• Dust nucleation and growth [Woitke & Helling (2003),(2004)]

• Alfven ionization, grain discharges, lightning, [Helling (2012), Stark, Helling & Rimmer, Submitted]

• Effects outside the Atmosphere

• Cosmic Rays [Rimmer & Helling, Submitted]

• UV Photons

• IR Photons, X-Rays, Gamma Rays

• Meteorites, infalling dust, etc.

Thursday, 18 April 13

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OUR ION-NEUTRAL NON-EQUILIBRIUM NETWORK

• Over 100 species

• Up to C2H6

• Includes Cations, some Anions

• Treats atmospheric mixing

• Cosmic rays via atmospheric transport model

• Analytic radiative transfer

• Over 2000 Reactions

• Reversible: Neutral-Neutral, Three Body, Ion-Neutral

• Combustion Reactions and Capture Reactions

• Non-Reversible: Photodissociation, Photoionization, Cosmic Ray Ionization

Thursday, 18 April 13

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THE EFFECT OF COSMIC RAY AND UV PHOTOCHEMISTRY

Thursday, 18 April 13

Page 13: ASTROCHEMISTRY APPLIED TO PLANETS: COSMIC-RAY …conference.astro.ufl.edu/STARSTOLIFE/science_final/talks/... · 2013-04-29 · ASTROCHEMISTRY AND ATMOSPHERIC CHEMISTRY • Astrochemistry

RETURNING TO HD 189733 b

• The questions we set out to address: what causes the haze and what is it made of?

• Our results hint at cosmic ray ionization as a way to produce hazes in free-floating planets.

• Hazes run into a potential problem with hot Jupiters. UV photons seem to destroy hydrocarbons, and may impede PAH production.

• Maybe silicate grains account for this signature, and the winds are sufficiently strong to get the silicate grains high enough in the atmosphere...

• ... but have we really addressed the question at all?

Thursday, 18 April 13

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WHAT ABOUT HD 189733 b?

•We looked at a Jupiter-like planet and an HD 209458 b-like planet.

•Why not model HD 189733 b?

•Maybe cosmic rays and UV photons conspire to produce a PAH haze in hot Jupiters?

•This is the natural next step.

Thursday, 18 April 13