Structures in circumbinary disks: Prospects for observability

¹ Institute of Theoretical Physik and Astrophysics, Kiel University, Leibnitzstr. 15, 24098 Kiel, Germany
e-mail: ruge@astrophysik.uni-kiel.de
² Pulkovo Astronomical Observatory, Russian Academy of Sciences, Pulkovskoe shosse 65, 196140 St. Petersburg, Russia
³ Sobolev Astronomical Institute, St. Petersburg State University, Universitetskii pr. 28, 198504 St. Petersburg, Russia

Received: 25 April 2013
Accepted: 6 May 2015

Abstract

Context. During the past decade circumbinary disks have been discovered around various young binary stars. Hydrodynamical calculations indicate that the gravitational interaction between the central binary star and the surrounding disk results in global perturbations of the disk density profile.

Aims. We study the observability of characteristic large-scale disk structures resulting from the binary-disk interaction in the case of close binary systems.

Methods. We derived the structure of circumbinary disks from smoothed-particle hydrodynamic simulations. Subsequently, we performed radiative transfer simulations to obtain scattered light and thermal reemission maps. We investigated the influence of the binary mass ratio, the inclination of the binary orbit relative to the disk midplane, and the eccentricity of the binary orbit on observational quantities.

Results. We find that ALMA will allow tracing asymmetries of the inner edge of the disk and potentially resolving spiral arms if the disk is seen face-on. For an edge-on orientation, ALMA will allow detecting perturbations in the disk density distribution through asymmetries in the radial brightness profile. Through the asymmetric structure of the disks, areas are formed with a temperature 2.6 times higher than at the same location in equivalent unperturbed disks. The time-dependent appearance of the density waves and spiral arms in the disk affects the total re-emission flux of the object by a few percent.