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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

The life cycles of Be viscous decretion discs: The case of omega CMa

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Ghoreyshi, M. R. [1, 2] ; Carciofi, A. C. [1] ; Rimulo, L. R. [1] ; Vieira, R. G. [1] ; Faes, D. M. [1] ; Baade, D. [3] ; Bjorkman, J. E. [4] ; Otero, S. [5] ; Rivinius, Th. [6]
Total Authors: 9
[1] Univ Sao Paulo, Inst Astron Geofis & Ciencias Atmosfer, Rua Matao 1226, BR-05508900 Sao Paulo, SP - Brazil
[2] RIAAM, Maragha 55134441 - Iran
[3] European Org Astron Res Southern Hemisphere ESO, Karl Schwarzschild Str 2, D-85748 Garching - Germany
[4] Univ Toledo, Dept Phys Astron, MS111 2801 West Bancroft St, Toledo, OH 43606 - USA
[5] AAVSO, Cambdrige, MA - USA
[6] European Org Astron Res Southern Hemisphere ESO, Casilla 19001, Santiago 19 - Chile
Total Affiliations: 6
Document type: Journal article
Source: Monthly Notices of the Royal Astronomical Society; v. 479, n. 2, p. 2214-2228, SEP 2018.
Web of Science Citations: 6

We analysed V-band photometry of the Be star omega CMa, obtained during the last four decades, during which the star went through four complete cycles of disc formation and dissipation. The data were simulated by hydrodynamic models based on a time-dependent implementation of the viscous decretion disc (VDD) paradigm, in which a disc around a fast-spinning Be star is formed by material ejected by the star and driven to progressively larger orbits by means of viscous torques. Our simulations offer a good description of the photometric variability during phases of disc formation and dissipation, which suggests that the VDD model adequately describes the structural evolution of the disc. Furthermore, our analysis allowed us to determine the viscosity alpha, as well as the net mass and angular momentum (AM) loss rates. We find that alpha is variable, ranging from 0.1 to 1.0, not only from cycle to cycle but also within a given cycle. Additionally, build-up phases usually have larger values of a than the dissipation phases. Furthermore, during dissipation the outward AM flux is not necessarily zero, meaning that omega CMa does not experience a true quiescence (b)ut, instead, switches between a high to a low AM loss rate during which the disc quickly assumes an overall lower density but never zero. We confront the average AM loss rate with predictions from stellar evolution models for fast-rotating stars, and find that our measurements are smaller by more than one order of magnitude. (AU)

FAPESP's process: 16/16844-1 - Systems Engineering for GMACS: GMT AT-13 Project
Grantee:Daniel Moser Faes
Support type: Scholarships in Brazil - Post-Doctorate
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 type: Multi-user Equipment Program
FAPESP's process: 12/20364-4 - Beyond dust survival: the inner regions of protoplanetary disks
Grantee:Rodrigo Georgetti Vieira
Support type: Scholarships in Brazil - Post-Doctorate
FAPESP's process: 12/21518-5 - A study of the dynamical evolution of delta Scorpii
Grantee:Leandro Rocha Rímulo
Support type: Scholarships in Brazil - Doctorate
FAPESP's process: 15/17967-7 - Viscous decretion disks: theory and observations
Grantee:Alex Cavaliéri Carciofi
Support type: Regular Research Grants