Active OB stars: structure, evolution, mass loss and critical limits Proceedings IAU Symposium No. 272, 2010 © 2010 International Astronomical Union C. Neiner, G. Wade, G. Meynet & G. Peters DOI: 00.0000/X000000000000000X Emission Features in a B[e] Binary System V2028 Cyg J. Polster1'2, D. Korčáková2, V. Votruba1'2, P. Škoda2, M. Šlechta2 and B. Kučerová1 1Faculty of Science, Masaryk University in Brno, Kotlářská 2, 611 37 Brno, Czech Republic 2Astronomical Institute AV CR, Fricova 298, 251 65 Ondřejov, Czech Republic email: polster@physics.minii.cz, kor@sunstel.asu.cas.cz Abstract. We present a preliminary analysis of our six-year observation campaign of the B [e] stellar system V2028 Cyg (MWC 623). The time variability of spectral features is described. Keywords, emission-line, B[e], binaries, V2028 Cyg 1. Introduction A variable star V2028 Cyg (MWC 623) shows a B[e] phenomenon. The nature of the central object is very difficult to determine due to the extended circumstellar medium. The spectrum of V2028 Cyg is dominated by strong Balmer emissions, especially Ha. It also contains permitted and forbidden emission lines of low-ionized or neutral atoms (Fell, [Fell], [O I], ...). We present measurements of some emission features in spectra of our six-year observation campaign. 84 spectra in the Ha region were taken with Ondfejov 2m telescope using a coude slit spectrograph with resolving power Rna ~ 12500. Additional four spectra were obtained from the ELODIE archive (i?=42000 in the wavelength interval 3906 - 6811 A). 2. Radial velocities and bisectors Radial velocities of the metallic emissions were measured by Gaussian fitting. We used the double Gaussian method (Schneider & Young, 1980) for the wings and the polynomial fitting in the case of the peak to measure the Ha radial velocities. The overall behaviour of the Ha line profile is described by bisectors (Fig. 2). Fell6456Ä Fell 6417 A Fell 6318 Ä [Ol] 6300 Ä 3500 4000 4500 5000 5500 3500 4000 4500 5000 5500 3500 4000 4500 5000 5500 3500 4000 4500 5000 5500 JD-2450000 JD-2450000 JD-2450000 JD-2450000 Figure 1. Radial velocities of [O I] and Fe II emission lines. 0 Spectral variability of V2028 Cyg 3500 4000 4500 5000 5500 JD-2450000 3500 4000 4500 5000 5500 JD-2450000 3500 4000 4500 5000 5500 JD-2450000 3500 4000 4500 5000 5500 JD-2450000 Figure 2. Bisector points of Ha line in relative heights from 0.1 (wings) to 0.9 (peak). "'"% k _ * • ± 1 - at i- Si 4000 4500 JD-2450000 4000 4500 JD-2450000 Figure 3. Radial velocities of the Ha peak (left) and wings (right). The fitting function is plotted in the graph. 3. Conclusions Radial velocities of the metallic emissions (Fig. 1) show certain scatter, but no period or trend was found. There is a clear minimum of radial velocity in JD=2454155±17 in the case of Ha wings (Fig. 3). The peak velocity values are more scattered, but there can be resolved a minimum in JD=2454683±33. The bisector measurements (Fig. 2) reveal, that the whole lower part of the Ha profile (under the hump) behaves the same way as the wings. The peak above the hump varies differently. It indicates existence of at least two different kinematical environments in the envelope, where Ha emission arises. The half maximum widths of metallic lines are ~ 1 A, which restricts the maximum value of the velocity gradient in the region of their formation to ~ 50 km/s. No observed line shows P Cyg profile and the emissions of metals have a blue-shifted maximum. Currently, we are working on a numerical modeling of the bisector time variability in order to explain these observed phenomena. Acknowlegements This research is supported by grants 205/09/P476 (GA CR), 205/08/H005 (GA CR) LC06041 (MSMT CR) and MUNI/A/0968/2009. The Astronomical Institute Ondfejov is supported by a project AV0Z10030501. References Allen, D. A., Swings, J. P., 1976, AkA, 47, 293 Arkhipova, V. P., Ipatov, A. P., 1982, Soviet. Astron. Lett, 8, 298 Baranne, A., Queloz, D., Mayour, M., Adrianzyk, G., Knispel, G., Kohler, D., Lacroix, D., Meunier, J.-P, Rimbaud, G., Vin, A., 1996, A&AAS, 119, 373 Hörne, K., Wade, R. A., Szkody, P., 1986, MNRAS, 219, 791 Moultaka, L., Ilovaisky, S. A., Prugniel, P., Soubiran, C., 2004, PASP, 116, 693 Pych, W., 2004, PASP, 116, 148 Schneider, D. P., Young, P., 1980, ApJ, 238, 946 Skoda, P., Slechta, M., Honsa, J., 2002, PAICz, 90, 3 Zickgraf, F.-J., Stahl, O., 1989, AhA, 223, 165