1. Moon-Planet and Exoplanet-Star Couplings: Common Electrodynamic Interaction Mechanisms Throughout the Universe Joachim Saur, Timo Grambusch, Stefan Duling University of Cologne, Germany

2. Magnetic coupling: Satellite-planet Clarke et al., 2002

3. Magnetic coupling: Planet-star Radial distribution of Exoplanets Evidence for Planet-Star Coupling: HD 179949 Skolnik et al. (2003, 2005, 2008) Ca 3947 A line correlation with orbital period of 3.1 d Energy flux: 10 20 W

4. Our aim: Electromagnetic planet-star interaction for exoplanets has been studied by: – Ip et al. (2004), – Preusse et al. (2005, 2006) – Grießmeier et al. (2004, 2007) – Zarka (2007) – Lanza (2008, 2009) – Nichols (2011) – Poppenhaeger et a. (2010, 2011) This work: Energetics of the coupling, which is dominated by the Poynting flux.

5. Model for energy flux Calculate Poynting flux S= (E x B)/μ 0 Based on Alfven wing model by Neubauer (1980). Kivelson et al. 2004 Neubauer 1998 With internal field Exoplanet geometry Standard case

6. Total Poynting flux launched at satellite/planet Limitation: No considerations about the fate of the energy along the flux tube No partially reflection/transmission (Hess et al. 2010a,2010b) considered. No nonlinear reflection at central body (Jacobsen et al. 2007) considered. No conversion of Poynting flux into particle acceleration considered.

7. Benchmarking at Jupiter and Saturn Io: – Theory: 2 x 10 12 W – UV Observations: 1-10 x 10 10 W Europa: – Theory: 1-7 x 10 10 W – UV Observations: 1-5 x 10 8 W Ganymede: – Theory: 1-3 x 10 11 W – UV Observations: 2-15 x 10 8 W Callisto: – Theory: 0.3-6 x 10 9 W Enceladus: – Theory: 2x10 8 W – UV Observations: 10 6 -10 7 W

8. Estimated M A at all known 562 * exoplanets * until last Friday

9. Poynting flux for 192 exoplanets with M A <1

10. Summary Electromagnetic planet star coupling is possible if relative flow velocity < Alfven velocity. 192 of 562 exoplanets exhibit sub-Alfvenic interaction. Only a few exoplanets generate energy fluxes large enough to be detectable. HD 179949 b produces 10 20 W if both exoplanet and star have magnetic fields 10 x stronger than Jupiter and sun, respectively.

13. Parker Model for Properties near 564 Exoplanets

14. Modelled Energy Flux: HD179949 and companion T S = 9d, F M = 10 10 kg/s, r=0.045 AU, R S =1.19 R sun, T=10 7 K, spectral class: F8V