SPHERE Observations of Debris Disks

We present the first detection of scattered light from the hot dust around the nearby star HD 172555 and the new observations of debris disks around HD 15115 and HIP 79977 with SPHERE (Spectro-Polarimetric High-contrast Exoplanet REsearch) at VLT.  HD 172555 is a ~23 Myr A7V star at a distance of 28.6 pc. The spectral energy distribution of the disk shows a very pronounced silicate feature at 9.8 micron implying the presence of a
large amount of micron-sized "hot" dust grains. Using the polarimetric differential imaging technique with ZIMPOL (Zurich IMaging POLarimeter), we obtained high-contrast images of the debris disk with a spatial resolution of ~25 mas and an inner working angle of ~0.1 arcsec. By fitting a model of the spatial distribution of dust grains to these images, we find that the disk has a radius of 0.30-0.35 arcsec (~10 au) and an inclination of ~105 degrees. Our new high-contrast and high-resolution images of the debris disk "Blue needle" (HD 15115, a 25-100 Myr F4IV star at a distance of 48.2 pc) and HIP 79977 (a 15 Myr F2/3V star at a distance of 123 pc) in scattered (total intensity) and in polarized light provide a much clearer view of the disk structures and their asymmetries.


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