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Title: COMPACT DUST CONCENTRATION IN THE MWC 758 PROTOPLANETARY DISK

The formation of planetesimals requires that primordial dust grains grow from micron- to kilometer-sized bodies. Dust traps caused by gas pressure maxima have been proposed as regions where grains can concentrate and grow fast enough to form planetesimals, before radially migrating onto the star. We report new VLA Ka and Ku observations of the protoplanetary disk around the Herbig Ae/Be star MWC 758. The Ka image shows a compact emission region in the outer disk, indicating a strong concentration of big dust grains. Tracing smaller grains, archival ALMA data in band 7 continuum shows extended disk emission with an intensity maximum to the northwest of the central star, which matches the VLA clump position. The compactness of the Ka emission is expected in the context of dust trapping, as big grains are trapped more easily than smaller grains in gas pressure maxima. We develop a nonaxisymmetric parametric model inspired by a steady-state vortex solution with parameters adequately selected to reproduce the observations, including the spectral energy distribution. Finally, we compare the radio continuum with SPHERE scattered light data. The ALMA continuum spatially coincides with a spiral-like feature seen in scattered light, while the VLA clump is offset from the scatteredmore » light maximum. Moreover, the ALMA map shows a decrement that matches a region devoid of scattered polarized emission. Continuum observations at a different wavelength are necessary to conclude whether the VLA-ALMA difference is an opacity or a real dust segregation.« less
Authors:
; ; ;  [1] ;  [2] ;  [3] ;  [4] ;  [5]
  1. Departamento de Astronomía, Universidad de Chile, Casilla 36-D, Santiago (Chile)
  2. Department of Physics and Astronomy, California State University Northridge, 18111 Nordhoff Street, Northridge, CA 91330 (United States)
  3. Millenium Nucleus “Protoplanetary Disks in ALMA Early Science,” Universidad de Chile, Casilla 36-D, Santiago (Chile)
  4. School of Physical, Environmental and Mathematical Sciences, UNSW@ADFA, Canberra ACT 2600 (Australia)
  5. Centre for Astrophysics and Supercomputing, Swinburne University of Technology, P.O. Box 218, Hawthorn, VIC 3122 (Australia)
Publication Date:
OSTI Identifier:
22518717
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 813; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; COMPARATIVE EVALUATIONS; CONCENTRATION RATIO; COSMIC DUST; EMISSION; ENERGY SPECTRA; INTERSTELLAR GRAINS; OPACITY; PLANETS; PROTOPLANETS; STARS; STEADY-STATE CONDITIONS; TRAPPING; VISIBLE RADIATION