Moving shadows on the dusty disks of young stars

¹ Main Astronomical Observatory Pulkovo, Pulkovskoe shosse 65, St. Petersburg 196140, Russia e-mail: tamb@gao.spb.ru; grinin@vg1723.spb.edu
² Max-Planck-Institute für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany e-mail: weigelt@mpifr-bonn.mpg.de
³ Crimean Astrophysical Observatory, Crimea, Nauchny, Ukraine

Received: 22 July 2005
Accepted: 25 October 2005

Abstract

We investigate the formation of moving shadows on the circumbinary (CB) disk of young binary systems. Moving shadows can be created by a dusty disk wind of the secondary component. The densest parts of the dusty disk wind and the associated common envelope can be optically thick and may block the stellar radiation inside a certain solid angle, resulting in the appearance of a moving shadow zone. Its shape and size depends on the mass loss rate, the disk wind velocity, and optical properties of the dust. Our calculations show that the shadow zone is observable if the mass loss rate is greater than 10 per year. This shadow resembles a clock hand. If the orbit is an elliptical, the properties of this clock hand will change during the orbital motion of the secondary.