A NEW DIAGNOSTIC OF THE RADIAL DENSITY STRUCTURE OF Be DISKS

Autor(es)

Draper, Zachary H. ^[1] ; Wisniewski, John P. ^[1] ; Bjorkman, Karen S. ^[2] ; Haubois, Xavier ^[3] ; Carciofi, Alex C. ^[3] ; Bjorkman, Jon E. ^[2] ; Meade, Marilyn R. ^[4] ; Okazaki, Atsuo ^[5]

Afiliação do(s) autor(es)

^[1] Univ Washington, Dept Astron, Seattle, WA 98195 - USA

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

^[3] Univ Sao Paulo, Inst Astron Geofis & Ciencias Atmosfer, BR-05508900 Sao Paulo - Brazil

^[4] Univ Wisconsin, Space Astron Lab, Madison, WI 53706 - USA

^[5] Hokkai Gakuen Univ, Fac Engn, Toyohira Ku, Sapporo, Hokkaido 0628605 - Japan

• Tipo de documento: Artigo Científico
• Fonte: Astrophysical Journal Letters; v. 728, n. 2 FEB 20 2011.
• Citações Web of Science: 14

Resumo

We analyze the intrinsic polarization of two classical Be stars in the process of losing their circumstellar disks via a Be to normal B star transition originally reported by Wisniewski et al. During each of five polarimetric outbursts which interrupt these disk-loss events, we find that the ratio of the polarization across the Balmer jump (BJ+/BJ-) versus the V-band polarization traces a distinct loop structure as a function of time. Since the polarization change across the Balmer jump is a tracer of the innermost disk density whereas the V-band polarization is a tracer of the total scattering mass of the disk, we suggest that such correlated loop structures in Balmer jump-V-band polarization diagrams (BJV diagrams) provide a unique diagnostic of the radial distribution of mass within Be disks. We use the three-dimensional Monte Carlo radiation transfer code HDUST to reproduce the observed clockwise loops simply by turning ``on/off{''} the mass decretion from the disk. We speculate that counterclockwise loop structures we observe in BJV diagrams might be caused by the mass decretion rate changing between subsequent ``on/off{''} sequences. Applying this new diagnostic to a larger sample of Be disk systems will provide insight into the time-dependent nature of each system's stellar decretion rate. (AU)

• 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