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Description
Direct imaging of debris disks gives important information about their nature, their global morphology and allows to identify specific structures possibly in connection with the presence of gravitational perturbers. It is the most straightforward technique to observe planetary systems as a whole. We present the first resolved images of the debris disk around the young F-type star HD 160305, detected in scattered light using the VLT/SPHERE instrument in the near infrared. We used a post-processing method based on Angular Differential Imaging and synthetic images of debris disks produced with a disk modeling code (GRaTer) to constrain the main characteristics of the disk around HD160305. All of the point sources in the field of the IRDIS camera were analyzed with an astrometric tool to determine whether they are bound objects or background stars. We detect a very inclined (~82{deg}) ring-like debris disk located at a stellocentric distance of about 86au (deprojected width ~27au). The disk displays a brightness asymmetry between the two sides of the major axis, as can be expected from scattering properties of dust grains. We derive an anisotropic scattering factor g>0.5. A second right-left asymmetry is also observed with respect to the minor axis. We measure a surface brightness ratio of 0.73+/-0.18 between the bright and the faint sides. Because of the low signal-to-noise ratio (S/N) of the images we cannot easily discriminate between several possible explanations for this left-right asymmetry, such as perturbations by an unseen planet, the aftermath of the breakup of a massive planetesimal, or the pericenter glow effect due to an eccentric ring. Two epochs of observations allow us to reject the companionship hypothesis for the 15 point sources present in the field.
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