Volume 560, December 2013
|Number of page(s)||6|
|Section||Stellar structure and evolution|
|Published online||02 December 2013|
Observatorio Astronomico Nacional, Instituto de Astronomia, Universidad
Nacional Autonoma de Mexico,
2 University of North Carolina at Greensboro, Greensboro, NC 27402, USA
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
Accepted: 23 October 2013
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.
Key words: binaries: spectroscopic / circumstellar matter / stars: emission-line, Be / stars: individual: pi Aquarii / techniques: spectroscopic
Table 1 and π Aquarii spectra in FITS format are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (188.8.131.52) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/560/A30
© ESO, 2013
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