Discovery of an Extended Debris Disk around the F2 V Star HD 15745

Using the Advanced Camera for Surveys aboard the Hubble Space Telescope, we have discovered dust-scattered light from the debris disk surrounding the F2 V star HD 15745. The circumstellar disk is detected between 2.0 and 7.5 radius, corresponding to 128–480 AU radius. The circumstellar disk morphology is asymmetric about the star, resembling a fan, and consistent with forward scattering grains in an optically thin disk with an inclination of ∼67 to our line of sight. The spectral energy distribution and scattered light morphology can be approximated with a model disk composed of silicate grains between 60 and 450 AU radius, with a total dust mass of 10 7 M, (0.03 M), representing a narrow grain size distribution (1–10 mm). Galactic space motions are similar to the Castor moving group, with an age of ∼10 8 yr, although future work is required to determine the age of HD 15745 using other indicators. Subject headings: circumstellar matter — stars: individual (HD 15745)

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