Numerical Plasma Simulation, Technical University of Braunschweig, Germany Extrasolar Planets General Properties and Magnetospheric Aspects Uwe Motschmann Institute for Theoretical Physics, Technical University of Braunschweig, Germany Co-workers: J.M. Griessmeier, TU Braunschweig S. Preusse, MPS Katlenburg-Lindau E. Kuehrt, DLR Berlin H. Rucker, IWF Graz G. Mann, AIP Potsdam A. Lipatov, Moscow Workshop Solar Terrestrial Interactions, Sinaia, September 2005

Numerical Plasma Simulation, Technical University of Braunschweig, Germany Outline Discovery Properties Detection techniques Magnetic interaction with the host star Planetary radio emission

Numerical Plasma Simulation, Technical University of Braunschweig, Germany Known Extrasolar Planets (ESP) (24 August 2005) 163 planets 139 planetary systems [ First ESP was detected in 1995 [Mayor & Queloz, Nature,1995]

Numerical Plasma Simulation, Technical University of Braunschweig, Germany Distribution of ESP They are everywhere! [

Numerical Plasma Simulation, Technical University of Braunschweig, Germany Definition of ESP Spherical metal rich non-fusor in an orbit around a fusor outside the solar system [Neuhäuser,

Numerical Plasma Simulation, Technical University of Braunschweig, Germany Orbital Radii [ “Hot Jupiters”: ~30 planets with d<0.1 AU (2004) Terrestrial planets: not (yet) detectable ?

Numerical Plasma Simulation, Technical University of Braunschweig, Germany Detection Techniques direct imaging radial velocity method (Doppler shift) transit (dimming of star) secondary transit (dimming of planet) astrometry microlensing

Numerical Plasma Simulation, Technical University of Braunschweig, Germany Detection by Doppler Shift (Radial Velocity Method) Motion around center of mass → shift of spectral lines. Detected ESP parameters: M sin(i), T, e

Numerical Plasma Simulation, Technical University of Braunschweig, Germany Detection by Transit Transit of planet in front of the star → decrease of total intensity (1). Detected ESP parameters: M, T, R

Numerical Plasma Simulation, Technical University of Braunschweig, Germany Detection by Secondary Transit Second. transitPrimary transit transit in front of star  decrease of total intensity (1) transit behind star  decrease of IR intensity (0.25)  planetary emission temperature of planet

Numerical Plasma Simulation, Technical University of Braunschweig, Germany Detection by Astrometry motion around center of mass → observed motion of the star. Detected parameters: M, T

Numerical Plasma Simulation, Technical University of Braunschweig, Germany Detection by Microlensing Light from a distant star focussed by gravity → fine structure caused by planet. Detected parameters: M p /M s, R, orbit

Numerical Plasma Simulation, Technical University of Braunschweig, Germany Direct Imaging Infrared or vis imaging (adaptive optics) → optical separation of planet possible. Detected parameters: R, spectrum [Neuhäuser et al, A&A, 2005]

Numerical Plasma Simulation, Technical University of Braunschweig, Germany Summary: Detection Methods 1? (2005) (GP Lupi) Direct obs (Gl 876 b) Astro- metry 28> (O235/ M53) 2000 (HD b) 1995 (51 Peg b) Micro- lensing Transit Doppler shift Second. Transit 2004 (HD b) 2

Numerical Plasma Simulation, Technical University of Braunschweig, Germany Magnetic Interaction of ESP Interaction of ESP with stellar wind –Stellar wind –ESP (planetary magnetic field, …) Action of the stellar wind to ESP Re-action of the ESP to star Purpose of the study –New phenomena compared with solar system –Observable consequences: superflares, planetary radio emission

Numerical Plasma Simulation, Technical University of Braunschweig, Germany Stellar Wind Models Parker [1958] hydrodynamic approach spherical symmetry no rotation no selfconsistent magnetic field Weber & Davis [1967] magnetohydrodynamic approach axisymmetric rotation magnetic field

Numerical Plasma Simulation, Technical University of Braunschweig, Germany Parker’s Wind Nozzle radius / critical radius distance / critical radius Velocity / sound speed Sonic point R crit ☼ = 8 ·10 6 km = 0.05 AU

Numerical Plasma Simulation, Technical University of Braunschweig, Germany Weber and Davis’ Wind → 3 characteristic points: Alfven point, supermagnetosonic point, submagnetosonicsonic point. → comparison with ESP position

Numerical Plasma Simulation, Technical University of Braunschweig, Germany distance in AU velocity in kms -1 Hot Jupiter orbits T= K T= K Velocities much lower with respect to 1 AU ESP may be located within Alfvén point! [Preusse et al, A&A, 2005] [Lipatov et al, PSS, 2005 ] Weber and Davis’ Wind P rot = 3d B surf = 1…10G

Numerical Plasma Simulation, Technical University of Braunschweig, Germany Magnetic Communication Close-in ESP Solar System stellar wind velocity Alfvén velocity Planetary disturbance is carried away by stellar wind Planetary disturbance can reach the star * ESP

Numerical Plasma Simulation, Technical University of Braunschweig, Germany Superflares Stellar flare –catastrophic release of magnetic energy with particle acceleration and emission of elm radiation Superflare –flare at solar like star with total energy release >100 x energy of most intensive solar flares (>3000 x vis, >1000 x in X-ray) Superflare rate – ~10 1 …10 2 y [Schaefer et al, 2000] No solar superflare in last 2000y

Numerical Plasma Simulation, Technical University of Braunschweig, Germany Triggering of Superflares Reconnection in double star system [Simon et al, 1980] Reconnection of the stellar magnetic field with a close-in magnetized planetary companion [Rubenstein & Schaefer, 2000]

Numerical Plasma Simulation, Technical University of Braunschweig, Germany Internal Magnetic Field of ESP Theoretical models  scaling laws for magnetic moment [Sano, 1993] e.g. Conditions for large magnetic moment:  high density:possible  fast rotation:limited by tidal locking  large planet:possible

Numerical Plasma Simulation, Technical University of Braunschweig, Germany Scaling Laws for Magnetic Moment Busse 1976 Curtis and Ness 1986 Mizutani et al Sano 1993

Numerical Plasma Simulation, Technical University of Braunschweig, Germany Tidal Locking of Close-in ESP Tidal force  bulge on planet Fast rotation  bulge displaced relative to star Gravitation acts on tidal bulge  spin-down After some time: rotation=revolution

Numerical Plasma Simulation, Technical University of Braunschweig, Germany Timescale for Locked Rotation tidally locked not tidally locked 10 Gyr0.1 Gyr [Griessmeier et al, A&A, 2004]

Numerical Plasma Simulation, Technical University of Braunschweig, Germany Magnetic Moment and Tidal Locking strongly reduced magnetic moment Tidal locking  [Griessmeier et al, A&A, 2004]

Numerical Plasma Simulation, Technical University of Braunschweig, Germany Size of Magnetosphere Dipole field: Distance magnetopause – planet: m n v 2  B p 2 /2μ 0 B p  M/R M 3 Magnetopause size: Pressure equilibrium at substellar point: R M  M 1/3 (n v 2 ) -1/6 d 1/3

Numerical Plasma Simulation, Technical University of Braunschweig, Germany Stellar Wind Evolution 5.2 Gyr Strong time dependence of stellar wind velocity and density  Influences size of the magnetosphere

Numerical Plasma Simulation, Technical University of Braunschweig, Germany Size of Magnetosphere

Numerical Plasma Simulation, Technical University of Braunschweig, Germany Planetary Radio Emission in the Solar System Flux density normalized to 1 AU [Bastian et al, APJ. 545, 2000] Strongly magnetized planets are nonthermal radio emitters! ionospheric cutoff

Numerical Plasma Simulation, Technical University of Braunschweig, Germany Cyclotron Maser Instability (CMI) refraction index argument of Besselfunction Lorentz factor - resonant wave particle interaction - dispersion relation for X mode [Wu & Lee, 1979]

Numerical Plasma Simulation, Technical University of Braunschweig, Germany Power input (stellar wind): Magnetosphere: Empirical scaling: [Zarka et al, Astrophys. Space Sci., 277, 293, 2001] P rad  P SW P SW  (R M /d) 2 R M (M, d) Planetary Radio Emission

Numerical Plasma Simulation, Technical University of Braunschweig, Germany Tau Bootes b as Radio Candidate Radio Flux normalized to 1AU [Griessmeier et al, 2005]

Numerical Plasma Simulation, Technical University of Braunschweig, Germany Radio Contrast Jupiter/Sun Φ J / Φ QS  10 3 [Griessmeier et al, A&A, 2005]

Numerical Plasma Simulation, Technical University of Braunschweig, Germany Contrast ESP/Star Vis10 -8 [Burrows et al, APJ, 2004] IR [Burrows et al, APJ, 2004] Radio>1 (>>1)[Griessmeier et al, A&A, 2005] Contrast: Poynting flux of ESP / Poynting flux of star

Numerical Plasma Simulation, Technical University of Braunschweig, Germany Radio Flux Reaching Earth Robin 2: sensitivity 100 mJy at 8-80 MHz ready ca. 2005? LOFAR: sensitivity mJy at MHz ready 2006/08? [

Numerical Plasma Simulation, Technical University of Braunschweig, Germany Outlook Missions with defined launch time –COROT (F, Europe, Nov 2005) –KEPLER (NASA, Oct 2006) –[EDDINGTON (ESA, 2008+)] –Space Interferometry Mission (NASA, 2009) –James Webb Space Telescope (ESA, NASA, 2009+) –GAIA (ESA, ) Planned missions –Big Occulting Steerable Satellite –UMBRAS –DARWIN (ESA) –Galactic Exoplanet Survey Telescope –Planet Imager (NASA) –Terrestrial Planet Finder (NASA)