1. Photochemistry in the Atmospheres of Hot Jupiters Yuk L. Yung 1, Mao-Chang Liang 2, Michael Line 1 and Giovanna Tinetti 3 1 Division of Geological and Planetary Sciences, California Institute of Technology, USA 2 Research Center for Environmental Changes, Academia Sinica, Taiwan 3 University College London, UK. Molecules in the Atmospheres of Extrasolar planets Paris, Nov 19-21, 2008

2.  Start with colder planets  HD209458b  H2O, CO, CO2, CH4 and hydrocarbons  Sulfur species, Nitrogen species  Lessons from solar system Today’s Outline

9. HD209458b

10. Chemical processes Chemical composition different from that of Jupiter –CO and H 2 O are abundant; CH 4 not abundant UV radiation a lot more enhanced –Can break up more molecules –Boost subsequent chemical reactions Performing photochemical calculation for HD 209458b

11. Properties of HD 209458b “Best known” planet –First discovered transiting planet (Henry et al. 2000) –First atmosphere detection (Charbonneau et al. 2001) –First exosphere detection (Vidal-Madjar et al. 2003) Orbiting HD 209458 G0V-type star –~0.05 AU or 3.5 days Inclination angle ~85  Radius 1.54 R J and mass 0.68 M J

12. One-dimensional photochemical model Solving mass continuity equation – –K zz = K 0  n - ,   0.5 Temperature profile from thermochemical calculation Chemical reactions from, for example, Yung and DeMore (1999)

13. Temperature profiles Barman et al. 2002 Fortney et al. 2003 Seager et al. 2000 Jupiter F/4  F/2 

14. Model atmosphere

16. Atomic Hydrogen H Production high H/H 2 ratio H 2 O + h  H + OH OH + H 2  H 2 O + H Net: H 2 + h  2H H 2 O Production CO + h  C + O O + H 2  OH + H OH + H 2  H 2 O + H Net: CO + 2H 2 + h  C + H 2 O + 2H

17. Hydrocarbons CO + h  C + O C + H 2 + M  3 CH 2 + M 2 3 CH 2  C 2 H 2 + 2H C 2 H 2 + H + M  C 2 H 3 + M C 2 H 3 + H 2  C 2 H 4 + H C 2 H 4 + H + M  C 2 H 5 + M C 2 H 5 + H  2CH 3 CH 3 + H + M  CH 4 + M CH 4 Production bottleneck

18. 2  [CO + h  C + O] 2  [C + H 2 + M  3 CH 2 + M] 3 CH 2 + 3 CH 2  C 2 H 2 + 2H C 2 H 2 + H + M  C 2 H 3 + M C 2 H 3 + H 2  C 2 H 4 + H C 2 H 4 + H + M  C 2 H 5 + M C 2 H 5 + H  2CH 3 2  [ CH 3 + H + M  CH 4 + M] 2  [ O + H 2  OH + H] 2  [ OH + H 2  H 2 O + H] 2  [ H + H + M  H 2 + M] net 2CO + 3H 2  CH 4 + 2H 2 O

25. N2N2 N NH 3 HCN CH 3 NH 2 NONH CN NH 2

27. H2SH2S SHS S2S2 S3S3 SO S4S4 S5S5 S6S6 S8S8 SO 2 H 2 SO 4 SO 3 HSO

31. [Friedson et al., Icarus, 2002]

35. Conclusions Common photochemistry: hundreds of molecules, thousands of reactions Similar Processes: Catalytic cycles, evolution, hydrodynamic escape, thermal inversion Advice to modelers: Dans ce meilleur des mondes possibles … tout est au mieux. (In this best of possible worlds … all is for the best.) Advice to observers: Dieu n’est par pour les gros bataillons, mais pour ceux qui tirent le mieux. (God is on the side not of the heavy battalions, but of the best shots.)

36. Acknowledgements NASA and ESA Yung’s Group at Caltech Liang Ph.D. Thesis 2005 Meadows et al. 2008 Yung and DeMore (1999) Book

37. Back-up slides

38. OCS

41.  Common photochemistry: hundreds of molecules, thousands of reactions  Similar Processes: Catalytic cycles, evolution, hydrodynamic escape, thermal inversion  Advice to modelers: Dans ce meilleur des mondes possibles … tout est au mieux (In this best of possible worlds … all is for the best.)  Advice to observers: Dieu n’est par pour les gros bataillons, mais pour ceux qui tirent le mieux. (God is on the side not of the heavy battalions, but of the best shots.) Conclusions