A Resolved Debris Disk around the G2 V Star HD 107146

We present resolved scattered-light images of the debris disk around HD107146, a G2 star 28.5 pc from the Sun. This is the first debris disk to beresolved in scattered light around a solar-type star. We observed it with theHST/ACS coronagraph, using a 1.8'' occulting spot and the F606W (broad V) andF814W (broad I) filters. Within 2'' from the star, the image is dominated byPSF subtraction residuals. Outside this limit, the disk looks featurelessexcept for a northeast-southwest brightness asymmetry that we attribute toforward scattering. The disk has scattered-light fractional luminosities of$(L_{Sca}/L_*)_{F606W}=6.8 \pm 0.8 \times 10^{-5}$ and$(L_{Sca}/L_*)_{F814W}=10 \pm 1 \times 10^{-5}$ and it is detected up to 6.5''away from the star. To map the surface density of the disk, we deproject it by$25^\circ \pm 5^\circ$, divide by the dust scattering phase ($g_{F606W} = 0.3\pm 0.1$, $g_{F814W} = 0.2 \pm 0.1$) and correct for the geometric dilution ofstarlight. Within the errors, the surface density has the same shape in eachbandpass, and it appears to be a broad (85 AU) ring with most of the opacityconcentrated at 130 AU. The ratio of the relative luminosity in F814W to thatin F606W has the constant value of $1.3\pm0.3$, with the error dominated byuncertainties in the value of $g$ in each filter. An examination of farinfrared and submillimeter measurements suggests the presence of small grains.The colors and the derived values of $g$ are consistent with the presence ofdust particles smaller than the radiation pressure limit. The dust generated bythe creation of a small planet or the scattering and circularization of a largeone, are possible scenarios that may explain the shape of the surface densityprofile.Comment: To appear in ApJ Letters Figure 3 in the original version had the wrong vertical scale. In this version it has been replaced by the correct on