Disk Substructures at High Angular Resolution

The Disk Substructures at High Angular Resolution Project (DSHARP) is one of the initial Large Programs conducted with ALMA. The primary goal of DSHARP is to find and characterize substructures in the spatial distributions of solid particles for a sample of 20 nearby protoplanetary disks, using very high resolution – approximately 0.035 arcseconds or 5 Astronomical Units (AU), Full Width at Half Maximum (FWHM) ­– observations of their 240 GHz (1.25 mm) continuum emission. These data provide a first homogeneous look at the small-scale features in disks that are directly relevant to the planet formation process, quantifying their prevalence, morphologies, spatial scales, spacings, symmetry, and amplitudes, for targets with a variety of disk and stellar host properties. The authors find that these substructures are ubiquitous in this sample of large, bright disks. They are most frequently manifested as concentric, narrow emission rings and depleted gaps, although large-scale spiral patterns and small arc-shaped azimuthal asymmetries are also present in some cases. These substructures are found at a wide range of disk radii (from a few AU to more than 100 AU), are usually compact (≤ 10 AU), and show a wide range of amplitudes (brightness contrasts). In this overview contribution, the authors discuss the motivation for the DSHARP project, describe the survey design and the sample properties, detail the observations and data calibration, highlight some basic results, and provide a general overview of the key conclusions that are presented in more detail in a series of accompanying articles, also published in Astrophysical Journal Letters. The DSHARP data – including visibilities, images, calibration scripts, and more – are released for community use at https://almascience.org/alma-data/lp/DSHARP. 

Image: ALMA's high-resolution images of nearby protoplanetary disks from the Disk Substructures at High Angular Resolution Project (DSHARP). Credit: ALMA (ESO/NAOJ/NRAO), S. Andrews et al.; NRAO/AUI/NSF, S. Dagnello.

Publication: Sean M. Andrews (Harvard–Smithsonian Center for Astrophysics) et al., The Disk Substructures at High Angular Resolution Project (DSHARP): I. Motivation, Sample, Calibration, and Overview, Astrophysical Journal Letters, 869, L41 (12 December 2018).

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