Cool Stars 14 - Submitted Abstract # 236
This version created on 05 October 2006

Water Delivery and Giant Planet Orbital Limits for Habitable Planet
Formation


Sean Raymond, University of Colorado
Avi Mandell, Pennsylvania State University

Terrestrial planets are thought to form in a bottom-up accretion
scenario, from km-sized "planetesimals" and Moon-sized "planetary
embryos".  During this process, water is accreted by the inner planets
by impacts from bodies originating in distant, colder regions of the
disk.  Giant planets are constrained to form in the few Myr lifetimes
of gaseous disks;  more quickly than terrestrial planets.  Thus, the
final stages of terrestrial accretion are strongly affected by any
giant planets that are present.  Since giant planets are easier to
detect, we can use the distribution of known giant planets to infer
the unknown properties of terrestrial planets.  We establish limits on
the giant planet orbits that permit the formation of a terrestrial
planet in the habitable zone of its parent star.  These limits apply
to systems like our own with giant planets outside the terrestrial
planet zone, and also to systems with close-in giant planets.
Dynamical simulations show that Earth-sized terrestrial planets can
form after giant planet migration, often with orbits in the habitable
zone.  Such planets accrete a very large amount of water and are
likely to be covered in global oceans.  More than a third of the known
systems of giant planets could have formed a terrestrial planet in the
habitable zone.  Thanks to the Virtual Planetary Laboratory, a NASA
Astrobiology center, for funding.

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