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 Title: HST/ACS Observations of Debris Disks Around Solar-Type Stars

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 Authors:

        John Krist, JPL
        David Ardila, JHU
        David Golimowski, JHU
        Mark Clampin, NASA/GSFC
        Holland Ford, JHU
        Garth Illingworth, UCO/Lick
        The HST/ACS Science Team

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 Abstract:

Of the few currently-known circumstellar debris disks that have been imaged in reflected light, most are associated with early-type stars. Such disks around later, solar-type sources are more elusive because the stars are not luminous enough to heat the disks to levels that were readily detectable by IRAS, the prior main source of disk candidates. Recent technological advancements, such as sensitive submillimeter instruments and the Spitzer Space Telescope, are providing new lists of debris disks around lower luminosity stars. Using these, the Advanced Camera for Surveys (ACS) Science Team has undertaken an ACS/HRC coronagraphic imaging study that concentrates on detecting and characterizing the debris disks around later-type (G-M) stars in visible light. The ACS coronagraph is currently the most sensitive instrument for scattered-light imaging of debris disks beyond one arcsecond from the central stars. We present recent ACS images of the disks around AU Mic (M0V) and HD 107146 (G2V). Both disks have central zones apparently devoid of scattering material, suggestive of tidal clearing by unseen low-mass companions. The AU Mic disk also contains localized density enhancements indicating some sort of gravitational perturbation. We will also provide an update on the most recent ACS observations of Spitzer-identified candidate disks.

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