Scattered light mapping of protoplanetary disks

Abstract

High-contrast scattered light observations have revealed the surface morphology of several dozens of protoplanetary disks at optical and near-infrared wavelengths. Inclined disks offer the opportunity to measure part of the phase function of the dust grains that reside in the disk surface which is essential for our understanding of protoplanetary dust properties and the early stages of planet formation. We aim to construct a method which takes into account how the flaring shape of the scattering surface of an (optically thick) protoplanetary disk projects onto the image plane of the observer. This allows us to map physical quantities (scattering radius and scattering angle) onto scattered light images and retrieve stellar irradiation corrected (r^2-scaled) images and dust phase functions. We apply the method on archival polarized intensity images of the protoplanetary disk around HD 100546 that were obtained with VLT/SPHERE in R'-band and VLT/NACO in H- and Ks-band. The brightest side of the r^2-scaled R'-band polarized intensity image of HD 100546 changes from the far to the near side of the disk when a flaring instead of a geometrically flat disk surface is used for the r^2-scaling. The decrease in polarized surface brightness in the scattering angle range of ~40-70 deg is likely a result of the dust phase function and degree of polarization which peak in different scattering angle regimes. The derived phase functions show part of a forward scattering peak which indicates that large, aggregate dust grains dominate the scattering opacity in the disk surface. Projection effects of a protoplanetary disk surface need to be taken into account to correctly interpret scattered light images. Applying the correct scaling for the correction of stellar irradiation is crucial for the interpretation of the images and the derivation of the dust properties in the disk surface layer.

Accepted for publication in A&A, 6 pages, 3 figures

References in corpus (10)

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• Direct detection of scattered light gaps in the transitional disk around HD 97048 with VLT/SPHERE
• ALMA hints at the presence of two companions in the disk around HD 100546
• Subaru Imaging of Asymmetric Features in a Transitional Disk in Upper Scorpius
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• HD100546 Multi-Epoch Scattered-Light Observations
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Cited by in corpus (13)

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• Images of Embedded Jovian Planet Formation At A Wide Separation Around AB Aurigae
• Direct detection of scattered light gaps in the transitional disk around HD 97048 with VLT/SPHERE
• The polarimetric imaging mode of VLT/SPHERE/IRDIS II: Characterization and correction of instrumental polarization effects
• Disk Evolution Study Through Imaging of Nearby Young Stars (DESTINYS): Late infall causing disk misalignment and dynamic structures in SU Aur
• Spiral arms in the proto-planetary disc HD100453 detected with ALMA: evidence for binary-disc interaction and a vertical temperature gradient
• Disks Around T Tauri Stars with SPHERE (DARTTS-S) II: Twenty-one new polarimetric images of young stellar disks
• Effect of dust size and structure on scattered light images of protoplanetary discs
• Dynamical Evidence of a Spiral Arm--Driving Planet in the MWC 758 Protoplanetary Disk
• The effects of dust evolution on disks in the mid-IR
• Disk Evolution Study Through Imaging of Nearby Young Stars (DESTINYS): A Panchromatic View of DO Tau's Complex Kilo-au Environment
• The Appearance of Vortices in Protoplanetary Disks in Near-Infrared Scattered Light
• Scattering and sublimation: a multi-scale view of $\mu$m-sized dust in the inclined disc of HD 145718