Disk structure and stirring mechanism in bright debris disks Authors: Péter Ábrahám, Attila Moór, Zoltán Balog, Carol A. Grady, Thomas Henning, Attila Juhász, Csaba Kiss, Ágnes Kóspál A significant fraction of main-sequence stars are encircled by dusty debris disks. Dust particles of these disks are replenished by destructive collisions between unseen planetesimals whose orbits are stirred up by some mechanism. While the most commonly invoked mechanism is self-stirring, alternative solutions, such as planetary stirring, are also possible. Here we present Herschel images of eight bright debris disks whose young age and relatively large disk size hint for stirring mechanism other than self-stirring. We spatially resolved all our targets with PACS, and detected them with SPIRE as well. We determined the inclinations, position angles, and outer radii of the disks by fitting a ring-like profile to the observed brightness distributions. We used the disk sizes as input parameters for modeling the spectral energy distributions, from which we estimated the dust distribution and the total dust mass in each system. We then compared the radii of the rings and ages of the systems to the theoretical predictions for the evolution of an outward expanding dust-production zone in the self-stirring model. We found several disks in our study that are too extended to be consistent with the self- stirring scenario. This result suggests that other physical mechanisms could contribute to the dynamical stirring of these disks. Assuming that we witness the effect of planetary stirring, some of our disks are prime targets for discovering outer giant planets via direct imaging. The eight resolved disks presented here, supplemented by two additional systems from our Herschel program, the hybrid debris disk of HD 21997, and the bright debris disk of the planet-host star HD 95086 (see Kospal et al., this conference), constitute a considerable contribution to the list of debris disks successfully resolved at far-infrared wavelengths.