Signatures of an eccentric disc cavity: Dust and gas in IRS 48

Josh Calcino, Daniel J. Price, Christophe Pinte, Nienke van der Marel, Enrico Ragusa, Giovanni Dipierro, Nicolás Cuello, Valentin Christiaens

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19 Citations (Scopus)

Abstract

We test the hypothesis that the disc cavity in the 'transition disc' Oph IRS 48 is carved by an unseen binary companion. We use 3D dust-gas smoothed-particle hydrodynamics simulations to demonstrate that marginally coupled dust grains concentrate in the gas overdensity that forms in the cavity around a low binary mass ratio binary. This produces high contrast ratio dust asymmetries at the cavity edge similar to those observed in the disc around IRS 48 and other transition discs. This structure was previously assumed to be a vortex. However, we show that the observed velocity map of IRS 48 displays a peculiar asymmetry that is not predicted by the vortex hypothesis. We show the unusual kinematics are naturally explained by the non-Keplerian flow of gas in an eccentric circumbinary cavity. We further show that perturbations observed in the isovelocity curves of IRS 48 may be explained as the product of the dynamical interaction between the companion and the disc. The presence of an ∼0.4 M☉ companion at an ∼10 au separation can qualitatively explain these observations. High spatial resolution line and continuum imaging should be able to confirm this hypothesis.

Original languageEnglish
Pages (from-to)2579-2587
Number of pages9
JournalMonthly Notices of the Royal Astronomical Society
Volume490
Issue number2
DOIs
Publication statusPublished - 1 Dec 2019

Keywords

  • Circumstellar matter
  • Hydrodynamics
  • Methods: numerical
  • Protoplanetary discs
  • Stars: individual: Oph IRS 48

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