[en] 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<SUB>⊙</SUB> 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.
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Calcino, Josh; University of Queensland, School of Mathematics and Physics
Price, Daniel J.; Monash University, School of Astrophysics
Pinte, Christophe; Monash University, School of Astrophysics, Institute de Planetologie et d'Astrophysique de Grenoble
van der Marel, Nienke; Herzberg Institute for Astronomy and Astrophysics
Ragusa, Enrico; University of Leicester, Department of Physics and Astronomy
Dipierro, Giovanni; University of Leicester, Department of Physics and Astronomy
Cuello, Nicolás; Pontifical Catholic University of Chile, Department of Astronomy and Astrophysics, Valparaiso University, Chile
Christiaens, Valentin ; Université de Liège - ULiège > Unités de recherche interfacultaires > Space sciences, Technologies and Astrophysics Research (STAR) ; Monash University, School of Astrophysics
Language :
English
Title :
Signatures of an eccentric disc cavity: Dust and gas in IRS 48
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