We present resolved scattered-light images of the debris
disk around HD 107146, a G2 star 28.5 pc from the Sun. We
observed it with the HST/ACS coronagraph, using the F606W
(broad V) and F814W (broad I) filters. Outside 2", the disk
looks featureless except for a northeast-southwest
brightness asymmetry that we attribute to forward
scattering. The disk has scattered-light fractional
luminosities of (LSca/L*)F606W=6.8 ±0.8 10-5
and (LSca/L*)F814W=10 ±1 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 ±5
degrees, divide by the dust scattering phase (gF606W =
0.3 ±0.1, gF814W = 0.2 ±0.1) and correct for the
geometric dilution of starlight. Within the errors, the
surface density appears to be a broad (85 AU) ring with most
of the opacity concentrated at 130 AU. The ratio of the
relative luminosity in F814W to that in F606W has the
constant value of 1.3±.3, with the error dominated by
uncertainties in the value of g in each filter. The colors
and the derived values of g are consistent with the
presence of dust particles as small as the radiation
pressure limit. The dust generated by the creation of a
small planet or the scattering and circularization of a
large one, are possible scenarios that may explain the shape
of the surface density profile.
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