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arXiv · 1101.3571

A New Diagnostic of the Radial Density Structure of Be Disks

Zachary H. Draper·John P. Wisniewski·Karen S. Bjorkman·Xavier Haubois·Alex C. Carciofi·Jon E. Bjorkman·Marilyn R. Meade·Atsuo Okazaki
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Abstract

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 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 3-D 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 counter-clockwise 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.

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Zachary H. Draper, John P. Wisniewski, Karen S. Bjorkman, Xavier Haubois, Alex C. Carciofi, Jon E. Bjorkman, Marilyn R. Meade, Atsuo Okazaki. 2011-01-18. A New Diagnostic of the Radial Density Structure of Be Disks. https://doi.org/10.1088/2041-8205%2F728%2F2%2Fl40

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