The Correlation Between H-alpha Emission and Visual Magnitude During Long-Term Variations in Classical Be Stars

T. A. A. Sigut and P. Patel

Department of Physics and Astronomy, The University of Western Ontario, London, Ontario, CANADA N6A 3K7

H-alpha equivalent widths and UBV magnitudes are calculated for Be star disk models that grow in size and/or density with time. We show that these simple models are consistent with the known Be star classes of positive and inverse correlations between long-term variations in H-alpha and V magnitude as identified by Harmanec. We support the conclusion of Harmanec that the distinction is controlled by the inclination of the disk to the line of sight. We demonstrate that the strength of these correlations, particularly those of an inverse correlation where the system becomes fainter as the H-alpha emission strength grows, is strongly influenced by the scale height of the inner Be star disk and the extent of the gravitational darkening of the central B star due to rapid rotation. This dependence may allow coordinated spectroscopic and photometric observations to better constrain these poorly known Be star parameters.

Accepted by The Astrophysical Journal
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or on the web at: arXiv:1301.3721


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