Aims. The work is aimed at studying the circumstellar disk of the bright
classical binary Be star π Aqr.
Methods. We analysed variations of a double-peaked profile of the
Hα emission line in the spectrum of π Aqr
that was observed in many phases during ~40 orbital cycles in 2004−2013. We applied the
discrete Fourier transform (DFT) method to search for periodicity in the peak intensity
ratio (V/R). Doppler tomography was used to study the structure of the disk around the
primary.
Results. The dominant frequency in the power spectrum of the
Hα V/R ratio is 0.011873 day-1, which
corresponds to a period of 84.2(2) days and agrees with the earlier determined orbital
period of the system, Porb = 84.1 days. The V/R shows a
sinusoidal variation that is phase-locked with the orbital period. Doppler maps of all our
spectra show a non-uniform structure of the disk around the primary: a ring with the inner
and outer radii at Vin ≈ 450 km s-1 and
Vout ≈ 200 km s-1, respectively, along with an
extended stable region (spot) at Vx ≈ 225
km s-1 and Vy ≈ 100
km s-1. The disk radius of ≈65 R⊙ = 0.33 AU was
estimated by assuming Keplerian motion of a particle on a circular orbit at the disk’s
outer edge
