THE FIRST DETERMINATION OF THE VISCOSITY PARAMETER IN THE CIRCUMSTELLAR DISK OF A Be STAR

Autor(es)

Carciofi, Alex C. ^[1] ; Bjorkman, Jon E. ^{[1, 2]} ; Otero, Sebastian A. ^[3] ; Okazaki, Atsuo T. ^[4] ; Stefl, Stanislav ^[5] ; Rivinius, Thomas ^[5] ; Baade, Dietrich ^[6] ; Haubois, Xavier ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Inst Astron Geofis & Ciencias Atmosfer, BR-05508900 Sao Paulo - Brazil

^[2] Univ Toledo, Dept Phys & Astron, Ritter Observ, Toledo, OH 43606 - USA

^[3] Amer Assoc Variable Star Observers, Cambridge, MA 02138 - USA

^[4] Hokkai Gakuen Univ, Fac Engn, Toyohira Ku, Sapporo, Hokkaido 0628605 - Japan

^[5] European Org Astron Res So Hemisphere, Santiago 19 - Chile

^[6] European Org Astron Res So Hemisphere, D-85748 Garching - Germany

• Tipo de documento: Artigo Científico
• Fonte: Astrophysical Journal Letters; v. 744, n. 1 JAN 1 2012.
• Citações Web of Science: 47

Resumo

Be stars possess gaseous circumstellar decretion disks, which are well described using standard alpha-disk theory. The Be star 28 CMa recently underwent a long outburst followed by a long period of quiescence, during which the disk dissipated. Here we present the first time-dependent models of the dissipation of a viscous decretion disk. By modeling the rate of decline of the V-band excess, we determine that the viscosity parameter alpha = 1.0 +/- 0.2, corresponding to a mass injection rate (M) over dot = (3.5 +/- 1.3) x 10(-8) M-circle dot yr(-1). Such a large value of a suggests that the origin of the turbulent viscosity is an instability in the disk whose growth is limited by shock dissipation. The mass injection rate is more than an order of magnitude larger than the wind mass-loss rate inferred from UV observations, implying that the mass injection mechanism most likely is not the stellar wind, but some other mechanism. (AU)

• Processo FAPESP: 10/19029-0 - Modelos tridimensionais de transporte radiativo: uma ponte entre teoria e observações
• Beneficiário: Alex Cavaliéri Carciofi
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 10/16037-2 - Investigando a física de discos circunstelares a partir de modelos de transporte radiativo
• Beneficiário: Alex Cavaliéri Carciofi
• Modalidade de apoio: Auxílio à Pesquisa - Pesquisador Visitante - Internacional
• Processo FAPESP: 09/07477-1 - Sondagem das atmosferas e ambientes circunstelares de estrelas Be e de estrelas evoluídas através da interferometria e polarimetria
• Beneficiário: Xavier Marie Alain Haubois
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado