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Paper: The Be Disk Structure in A 0535+262/V725 Tau During the X-Ray Giant Outburst
Volume: 464, Circumstellar Dynamics at High Resolution
Page: 285
Authors: Moritani, Y.; Nogami, D.; Okazaki, A. T.; Imada, A.; Kambe, E.; Honda, S.; Hashimoto, O.; Ichikawa, K.
Abstract: The famous Be/X-ray binary A 0535+262/V725 Tau stayed in outburst phase from 2008 to 2011, emitting several X-ray outbursts including the two giant outbursts in November/December 2009 and February 2011. We carried out a high-dispersion spectroscopic monitoring of A 0535+262, aiming at the Be disk structure in outburst phase, in particular during outbursts. Our observations could cover the 2009 giant outburst. Observed emission line profiles, reflecting the Be disk structure, showed drastic variabilities. Blue “shoulder” feature in Hα line profile after the periastrons indicates the dense gas stream from the outer part of the Be disk to the neutron star. Other features such as the redshifted enhanced component, the high equivalent width value and the departure from the V/R variabilities suggest that the Be disk had tidally warped component in recent years. We analyzed the radial velocity of the enhanced component and found that the giant outbursts were likely caused by enormous mass transfer from the warped Be disk to the neutron star.
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