SPHERE DPI image of HD121617 in J band

Based on our modeling results and archival photometry, we also model the SED to put constraints on the total dust mass and the dust size distribution. We explore different scenarios that could explain these new constraints. We present the first resolved image in scattered light of the debris disk HD 121617.

We fit the morphology of the disk, finding a semi-major axis of 78.3+/-0.2au, an inclination of 43.1+/-0.2{deg} and a position angle of the major axis with respect to north, of 239.8+/-0.3{deg}, compatible with the previous continuum and CO detection with ALMA. Our analysis shows that the disk has a very sharp inner edge, possibly sculpted by a yet-undetected planet or gas drag. While less sharp, its outer edge is steeper than expected for unperturbed disks, which could also be due to a planet or gas drag, but future observations probing the system farther from the main belt would help explore this further.

The SED analysis leads to a dust mass of 0.21+/-0.02M_{Earth}_ and a minimum grain size of 0.87+/-0.12um, smaller than the blowout size by radiation pressure, which is not unexpected for very bright collisionally active disks.