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 Title: 

            Photoevaporation of protoplanetary disks

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 Authors:

          Isamu Matsuyama, University of Toronto

          Norm Murray, Canadian Institute for Theoretical Physics

          Doug Johnstone, Herzberg Institute of Astrophysics

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 Abstract:

          The dominant disk removal mechanism for a wide range of conditions is viscous accretion, photoevaporation from the central source, and photoevaporation by external stars.  We describe the disk evolution under the influence of these mechanisms. The intrinsic stellar flux and viscous accretion may remove the disk in ~10 Myr. The disk lifetime is typically shorter for disks in stellar clusters since disk erosion is dominated by massive stars in this case. The disk lifetime is ~0.1-1 Myr in the neighbourhood of massive stars, and ~1 10 Myr at typical distances from these stars. Along with dispersing the disk, photoevaporation driven by the stellar flux and viscous accretion can produce structure in the disk such as gaps and rings. The natural formation of a gap in the disk at several AU, due to photoevaporation and viscous spreading, provides a possible halting mechanism for migrating massive planets.

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