AAS 197, January 2001
Session 60. Stars and Stellar Atmospheres
Oral, Tuesday, January 9, 2001, 10:30am-12:00noon, Royal Palm 5/6

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[60.01] Radiative Forces in Be Disks: Precession of Nearly Circular Orbits

K. Gayley, R. Ignace (U. of Iowa), S. Owocki (Bartol Res. Inst., U. of Delaware)

We apply the standard CAK treatment of partially optically thick line forces to an orbiting disk around a B-type star, to delineate the parameter regimes where the radiative force may be expected to alter the global disk properties. Also, even when these radiative forces are small, we quantify the potentially important ramifications for higher-order perturbations such as one-arm mode confinement and precession of nearly circular orbits. We find that optically thick radiative forces, both radial and azimuthal, should be expected to be present in a Keplerian Be disk, and may have far-reaching implications for dynamical simulations over mode-precession timescales. Although our analysis is limited to a linear treatment of nearly circular orbits, we speculate that radiative forces may even control the saturation and nonlinear precession of observed large-amplitude one-arm modes.

This work was supported in part by NASA grants NAG5-3530 and NAG5-4065.

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