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We present observations of the known edge-on debris disk around HIP 79977 (HD 146897, F star in Upper Sco, 123 pc), taken with the ZIMPOL differential polarimeter of the SPHERE instrument in the Very Broad Band filter ($lambda_c=735$ nm, $Deltalambda=290$ nm) with a spatial resolution of about 25 mas. We measure the polarization flux along and perpendicular to the disk spine of the highly inclined disk for projected separations between 0.2 (25 AU) and 1.6 (200 AU) and investigate the diagnostic potential of such data with model simulations. The polarized flux contrast ratio for the disk is $F_{pol}/F_ast= (5.5 pm 0.9) 10^{-4}$. The surface brightness reaches a maximum of 16.2 mag arcsec$^{-2}$ at a separation of $0.2-0.5$ along the disk spine with a maximum surface brightness contrast of 7.64 mag arcsec$^{-2}$. The polarized flux has a minimum near the star $<0.2$ because no or only little polarization is produced by forward or backward scattering in the disk section lying in front of or behind the star. The data are modeled as a circular dust belt with an inclination $i=85(pm 1.5)^circ$ and a radius between $r_0$ = 60 AU and 90 AU. The radial density dependence is described by $(r/r_0)^{alpha}$ with a steep power law index $alpha=5$ inside $r_0$ and a more shallow index $alpha=-2.5$ outside $r_0$. The scattering asymmetry factor lies between $g$ = 0.2 and 0.6 adopting a scattering angle-dependence for the fractional polarization as for Rayleigh scattering. Our data are qualitatively very similar to the case of AU Mic and they confirm that edge-on debris disks have a polarization minimum at a position near the star and a maximum near the projected separation of the main debris belt. The comparison of the polarized flux contrast ratio $F_{pol}/F_{ast}$ with the fractional infrared excess provides strong constraints on the scattering albedo of the dust.
We present Subaru/HiCIAO H-band high-contrast images of the debris disk around HIP 79977, whose pres- ence was recently inferred from an infrared excess. Our images resolve the disk for the first time, allowing characterization of its shape, size, an
We present new, near-infrared (1.1--2.4 $mu m$) high-contrast imaging of the bright debris disk surrounding HIP 79977 with the Subaru Coronagraphic Extreme Adaptive Optics system (SCExAO) coupled with the CHARIS integral field spectrograph. SCExAO/CH
We have obtained Hubble Space Telescope (HST) coronagraphic observations of the circumstellar disk around M star TWA 7 using the STIS instrument in visible light. Together with archival observations including HST/NICMOS using the F160W filter and Ver
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We performed observations of the Sco-Cen F star HD 117214 aiming at a search for planetary companions and the characterization of the debris disk structure. HD 117214 was observed with the SPHERE subsystems IRDIS, IFS and ZIMPOL at optical and near-I