Characterization of debris disks observed with SPHERE

Abstract

This study aims to characterize debris disks observed with SPHERE across multiple programs, with the goal of identifying systematic trends in disk morphology, dust mass, and grain properties as a function of stellar parameters. We analyzed a sample of 161 young stars using SPHERE observations at optical and near-IR wavelengths. Disk geometries were derived from ellipse fitting and model grids, while dust mass and properties were constrained by modified blackbody (MBB) and size distribution (SD) modeling of SEDs. The dynamical modeling was performed to assess whether the observed disk structures can be explained by the presence of unseen planets. We resolved 51 debris disks, including four new detections: HD 36968, BD-20 951, and the inner belts of HR 8799 and HD 36546. In addition, we found a second transiting giant planet in the HD 114082 system, with a radius of 1.29 $R_{\mathrm{Jup}}$ and an orbital distance of ~1 au. We identified nine multi-belt systems, with outer-to-inner belt radius ratios of $1.5-2$, and found close agreement between scattered-light and millimeter-continuum belt radii. They scale weakly with stellar luminosity ($R_{\mathrm{belt}}\propto L_{\star }^{0.11}$), but show steeper dependencies when separated by CO and CO${}_2$ freeze-out regimes. Disk fractional luminosities follow collisional decay trends, declining as $t_{\mathrm{age}}^{-1.18}$ for A and $t_{\mathrm{age}}^{-0.81}$ for F stars. The inferred dust masses span $10^{-5}-1M_{\oplus }$ from MBB and $0.01-1M_{\oplus }$ from SD modeling. These masses scale as $R_{\mathrm{belt}}^n$ with $n>2$ in belt radius and super-linearly with stellar mass, consistent with trends seen in protoplanetary disks. Analysing correlation between disk polarized flux and IR excess, we found an offset of ~1 dex between total-intensity (HST) and polarized fluxes. A new parametric approach to estimate dust albedo and maximum polarization fraction is introduced.

57 pages, 33 figures, 13 tables