Doppler tomography of the circumstellar disk of π Aquarii^⋆,⋆⋆

¹ Observatorio Astronomico Nacional, Instituto de Astronomia, Universidad Nacional Autonoma de Mexico, 22800 Ensenada BC Mexico
e-mail: zhar@astrosen.unam.mx
² University of North Carolina at Greensboro, Greensboro, NC 27402, USA
e-mail: a_mirosh@uncg.edu
³ Emil-Nolde-Str. 12, 51375 Leverkusen, Germany
⁴ Ritter Observatory, University of Toledo, Toledo, OH 43606, USA
⁵ 19 Boulevard Carnot, 21000 Dijon, France
⁶ Balmes, 2, 08784 Piera ( Barcelona), Spain
⁷ 6 rue Virgile, 42100 Saint-Etienne, France
⁸ ARAS, Astronomical Ring for Access to Spectroscopy, France
⁹ Observatoire de Juvignac, 19 avenue du Hameau du Golf, 34990 Juvignac, France
¹⁰ SAPP, CSC des Trois Cités, Le Clos Gaultier, 86000 Poitiers, France
¹¹ 16 Calade, St. Roch, 06410 Biot, France
¹² Observatoire du Val de l’Arc, route de Peynier, 13530 Trets, France
¹³ Ebnetstrasse 12, Bitsch, Switzerland
¹⁴ Castanet Tolosan Observatory, 6 place Clémence Isaure, 31320 Castanet Tolosan, France
¹⁵ Alpha Observatory, Alpine, Texas 79830, USA
¹⁶ Dorfstrasse 3f, 8603 Schwerzenbach, Switzerland
¹⁷ Observatoire de la Tourbiére, 38690 Chabons, France

Received: 21 June 2013
Accepted: 23 October 2013

Abstract

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 H_α 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 H_α 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, P_orb = 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 V_in ≈ 450 km s^-1 and V_out ≈ 200 km s^-1, respectively, along with an extended stable region (spot) at V_x ≈ 225 km s^-1 and V_y ≈ 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.