On the role of duplicity in the Be phenomenon

I. General considerations and the first attempt at a 3-D gas-dynamical modelling of gas outflow from hot and rapidly rotating OB stars in binaries

¹ Astronomical Institute of the Charles University, V Holešovičkách 2, 180 00 Praha 8 - Troja, Bohemia, Czech Republic
² Astronomical Institute of the Academy of Sciences of the Czech Republic, 251 65 Ondřejov, Bohemia, Czech Republic
³ Institute of Astronomy, Russian Academy of Sciences, Pyatnitskaya 48, Moscow 109017, Russia e-mail: bisikalo@inasan.rssi.ru; aboyar@inasan.rssi.ru
⁴ Keldysh's Institute of Applied Mathematics, Miusskaya Square 4, Moscow 125047, Russia e-mail: kuznecov@spp.keldysh.ru

Corresponding author: P. Harmanec, hec@sunstel.asu.cas.cz

Received: 24 July 2002
Accepted: 14 October 2002

Abstract

This paper begins a new series of studies devoted to a critical re-examination of the role of duplicity for the Be phenomenon and for the variability patterns observed for many Be stars. Based on both dynamical and energy considerations and a numerical gas-dynamical modelling, a new hypothesis of the formation of Be envelopes in binaries, via an outflow from a rapidly rotating B star in a detached binary, is outlined. It is shown that such an outflow is facilitated by the presence of a companion to the B star and leads to the formation of an envelope but not to any significant mass exchange between the binary components.