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Properties of the d Scorpii Circumstellar Disk from Continuum Modeling

UNCG Author/Contributor (non-UNCG co-authors, if there are any, appear on document)
Anatoly S. Miroshnichenko, Associate Professor (Creator)
Institution
The University of North Carolina at Greensboro (UNCG )
Web Site: http://library.uncg.edu/

Abstract: We present optical W BV R and infrared JHKL photometric observations of the Be binary system d Sco, obtained in 2000–2005, mid-infrared (10 and 18 µm) photometry and optical (?? 3200–10500 ^A) spectropolarimetry obtained in 2001. Our optical photometry confirms the results of much more frequent visual monitoring of d Sco. In 2005, we detected a significant decrease in the object’s brightness, both in optical and near-infrared brightness, which is associated with a continuous rise in the hydrogen line strenghts. We discuss possible causes for this phenomenon, which is difficult to explain in view of current models of Be star disks. The 2001 spectral energy distribution and polarization are successfully modeled with a three-dimensional non-LTE Monte Carlo code which produces a self-consistent determination of the hydrogen level populations, electron temperature, and gas density for hot star disks. Our disk model is hydrostatically supported in the vertical direction and radially controlled by viscosity. Such a disk model has, essentially, only two free parameters, viz., the equatorial mass loss rate and the disk outer radius. We find that the primary companion is surrounded by a small (7 R?), geometrically-thin disk, which is highly nonisothermal and fully ionized. Our model requires an average equatorial mass loss rate of 1.5 × 10-9M? yr-1.

Additional Information

Publication
http://arxiv.org/abs/astro-ph/0603274v2 18 Mar 2006
Language: English
Date: 2006
Keywords
Techniques, Photometric, Polarimetric, Methods, Numerical;stars, Emission-line, Be, Stars, Individual (d Scorpii), Circumstellar matter