Be discs in coplanar circular binaries: Phase-locked variations of emission lines

Author(s)

Panoglou, Despina ^[1] ; Faes, Daniel M. ^[2] ; Carciofi, Alex C. ^[2] ; Okazaki, Atsuo T. ^[3] ; Baade, Dietrich ^[4] ; Rivinius, Thomas ^[5] ; Fernandes, Marcelo Borges ^[1]

Affiliation

^[1] Observ Nacl, Rua Gen Jose Cristino 77, BR-20921400 Rio De Janeiro - Brazil

^[2] Univ Sao Paulo, Inst Astron Geofis & Ciencias Atmosfer, Rua Matao 1226, BR-05508900 Sao Paulo, SP - Brazil

^[3] Hokkai Gakuen Univ, Fac Engn, Toyohira Ku, Sapporo, Hokkaido 0628605 - Japan

^[4] European Org Astron Res Southern Hemisphere, Karl Schwarzschild Str 2, D-85748 Garching - Germany

^[5] European Org Astron Res Southern Hemisphere, Casilla 19001, Santiago 19 - Chile

• Document type: Journal article
• Source: Monthly Notices of the Royal Astronomical Society; v. 473, n. 3, p. 3039-3050, JAN 2018.
• Web of Science Citations: 6

Abstract

In this paper, we present the first results of radiative transfer calculations on decretion discs of binary Be stars. A smoothed particle hydrodynamics code computes the structure of Be discs in coplanar circular binary systems for a range of orbital and disc parameters. The resulting disc configuration consists of two spiral arms, and this can be given as input into a Monte Carlo code, which calculates the radiative transfer along the line of sight for various observational coordinates. Making use of the property of steady disc structure in coplanar circular binaries, observables are computed as functions of the orbital phase. Some orbital-phase series of line profiles are given for selected parameter sets under various viewing angles, to allow comparison with observations. Flat-topped profiles with and without superimposed multiple structures are reproduced, showing, for example, that triple-peaked profiles do not have to be necessarily associated with warped discs and misaligned binaries. It is demonstrated that binary tidal effects give rise to phase-locked variability of the violet-to-red (V/R) ratio of hydrogen emission lines. The V/R ratio exhibits two maxima per cycle; in certain cases those maxima are equal, leading to a clear new V/R cycle every half orbital period. This study opens a way to identifying binaries and to constraining the parameters of binary systems that exhibit phase-locked variations induced by tidal interaction with a companion star. (AU)

• FAPESP's process: 16/16844-1 - Systems Engineering for GMACS: GMT AT-13 Project
• Grantee: Daniel Moser Faes
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 15/17967-7 - Viscous decretion disks: theory and observations
• Grantee: Alex Cavaliéri Carciofi
• Support Opportunities: Regular Research Grants
• FAPESP's process: 13/16801-2 - Modelling the formation and evolution of inflowing and outflowing gaseous disks around stars
• Grantee: Despina Panoglou
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 09/54006-4 - A computer cluster for the Astronomy Department of the University of São Paulo Institute of Astronomy, Geophysics and Atmospheric Sciences and for the Cruzeiro do Sul University Astrophysics Center
• Grantee: Elisabete Maria de Gouveia Dal Pino
• Support Opportunities: Multi-user Equipment Program