Characterization of debris disks observed with SPHERE

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 $R_{\rm Jup}$ 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 ($R_{\rm belt} \propto L_{\star}^{0.11}$), but show steeper dependencies when separated by CO and CO$2$ freeze-out regimes. Disk fractional luminosities follow collisional decay trends, declining as $t{\rm age}^{-1.18}$ for A and $t_{\rm age}^{-0.81}$ for F stars. The inferred dust masses span $10^{-5}-1,M_\oplus$ from MBB and $0.01-1,M_\oplus$ from SD modeling. These masses scale as $R_{\rm belt}^n$ 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.

💡 Research Summary

This paper presents a comprehensive demographic study of debris disks, analyzing a large sample of 161 young, main-sequence stars observed with the SPHERE instrument at the Very Large Telescope. The primary aim is to identify systematic trends in disk morphology, dust mass, and grain properties as functions of stellar parameters, thereby placing debris disks within the broader context of planetary system formation and evolution.

The study combines high-contrast scattered-light imaging from SPHERE with spectral energy distribution (SED) modeling and dynamical simulations. The sample was compiled from archival data of various SPHERE programs, including the dedicated SHARDDS survey. Data analysis involved ellipse fitting and model grids to derive disk geometries, modified blackbody (MBB) and size distribution (SD) modeling to constrain dust properties and masses, and dynamical modeling to test planetary sculpting scenarios.

Key findings include:

• Detections: The team spatially resolved 51 debris disks. Among these are four new detections: the disks around HD 36968 and BD-20 951, and the inner belts of the well-known systems HR 8799 and HD 36546. Additionally, a second transiting giant planet was discovered in the HD 114082 system, with a radius of 1.29 Jupiter radii and an orbital distance of ~1 AU.
• Structural Properties: Nine multi-belt systems were identified, with outer-to-inner belt radius ratios between 1.5 and 2. Belt radii measured from scattered light and millimeter continuum emission show excellent agreement. Radii scale weakly with stellar luminosity (R ∝ L*^0.11) but exhibit steeper dependencies when separated by CO