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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: fundamental disc parameters of 54 SMC Be stars

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Author(s):
Rimulo, L. R. [1] ; Carciofi, A. C. [1] ; Vieira, R. G. [1] ; Rivinius, Th. [2] ; Faes, D. M. [1] ; Figueiredo, A. L. [1] ; Bjorkman, J. E. [3] ; Georgy, C. [4] ; Ghoreyshi, M. R. [1] ; Soszynski, I. [5]
Total Authors: 10
Affiliation:
[1] Univ Sao Paulo, Inst Astron Geofis & Ciencias Atmosfer, Rua Matao 1226, Cidade Univ, BR-05508900 Sao Paulo, SP - Brazil
[2] European Southern Observ, Alonso de Cordova 3107, Casilla 19001, Santiago 19 - Chile
[3] Univ Toledo, Dept Phys & Astron, Ritter Observ, Mail Stop 113, Toledo, OH 43606 - USA
[4] Observ Geneva, Chemin Maillettes 51, CH-1290 Sauverny, Versoix - Switzerland
[5] Univ Warsaw Observ, Al Ujazdowskie 4, PL-00478 Warsaw - Poland
Total Affiliations: 5
Document type: Journal article
Source: Monthly Notices of the Royal Astronomical Society; v. 476, n. 3, p. 3555-3579, MAY 2018.
Web of Science Citations: 11
Abstract

Be stars are main-sequence massive stars with emission features in their spectrum, which originates in circumstellar gaseous discs. Even though the viscous decretion disc model can satisfactorily explain most observations, two important physical ingredients, namely the magnitude of the viscosity (alpha) and the disc mass injection rate, remain poorly constrained. The light curves of Be stars that undergo events of disc formation and dissipation offer an opportunity to constrain these quantities. A pipeline was developed to model these events that use a grid of synthetic light curves, computed from coupled hydrodynamic and radiative transfer calculations. A sample of 54 Be stars from the OGLE survey of the Small Magellanic Cloud (SMC) was selected for this study. Because of the way our sample was selected (bright stars with clear disc events), it likely represents the densest discs in the SMC. Like their siblings in the Galaxy, the mass of the disc in the SMC increases with the stellar mass. The typical mass and angular momentum loss rates associated with the disc events are of the order of similar to 10(-10) M-circle dot yr(-1) and similar to 5 x 10(36) g cm(2) s(-2), respectively. The values of a found in this work are typically of a few tenths, consistent with recent results in the literature and with the ones found in dwarf novae, but larger than current theory predicts. Considering the sample as a whole, the viscosity parameter is roughly two times larger at build-up (<alpha(bu)> = 0.63) than at dissipation (<alpha(d)> = 0.26). Further work is necessary to verify whether this trend is real or a result of some of the model assumptions. (AU)

FAPESP's process: 15/17967-7 - Viscous decretion disks: theory and observations
Grantee:Alex Cavaliéri Carciofi
Support type: Regular Research Grants
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: 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: 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