The Be disc structure in A0535+262/V725 Tau during the X-ray giant outburst

A famous Be/X-ray binary A0535+262 was active from 2008 to 2011 emitting several X-ray outburst including the two giant 
outburst in December 2009 and Febuuary 2011.

We carried out the high-dispersion spectroscopic monitoring in order to reveal the mass-transfer mechanism in the outburst 
phase from the mass-doner point of view.

Our observations especially could cover the 2009 giant outburst.

Observed emission line profiles, reflecting the Be disc structure, showed the drastic variabilities.

Blue ``shoulder" feature in H-alpha line profile after the periastrons indicates the dense gas stream from the outer part of the 
Be disc to the neutron star.

Other features such as the redshifted enhancedment, the high EW value and the departure from the V/R variabilities suggest 
that the Be disc had tidally warped conponent in recent years.