DYNAMICAL HABITABILITY IN THE EXTRASOLAR PLANETARY SYSTEMS 47 URSAE MAJORIS AND 55 CANCRI Siegfried Franck Christine Bounama Werner von Bloh Potsdam Institute for Climate Impact Research 35th Meeting of the AAS Devision on Dynamical Astronomy Cannes/ France, April 19-24, 2004

HABITABLE ZONES HZ: range of orbital distances, where the physical conditions at the planet‘s surface are favorable for the existence of life

HZ := {R | Π(Patm(R,t), Ts(R,t)) > 0} HABITABLE ZONES HZ := {R | Π(Patm(R,t), Ts(R,t)) > 0}

THE EXOPLANETARY SYSTEM 47UMa The Star 47 Ursae Majoris Spectral Class: G0V Distance: 45 lightyears Luminosity: 1.54 Lsolar ( 0.13) Mass: 1.03 Solar Masses Age: 6.3 Gyr (+1.2, –1.0)

DYNAMICAL HABITABILITY Jones et al. (2001, 2002, 2003) MVS (Mixed Variable Symplectic Integration Method) eccentricity small (inside HZ); R outside 3 RHill Rout ~ 1.32 AU Noble et al. (2002) Gozdziewski (2002) Rout ~ 1.25 AU MEGNO (Mean Exponential Growth Factor of Nearby Orbits) Rout ~ 1.30 AU

RESULTS FOR 47UMa Cuntz, M., von Bloh, W., Bounama, C., Franck, S., Icarus 162, 214, 2003 Franck, S., Cuntz, M., von Bloh, W., Bounama, C., Int. J. Astrobiology 2(1), 35, 2003

CONCLUSIONS Possibility for dynamically habitable Earth-like planets in the systems 47 UMa and 55 Cnc Higher probability for „water worlds“ of being habitable www.pik-potsdam.de/PLACES