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Activity of the Be star 28 Cygni: 1985–1991

Published online by Cambridge University Press:  26 May 2016

Ž. Ružić ,
V. Vujnović ,
K. Pavlovski ,
H. Božić ,
J. R. Percy ,
A. Attard ,
P. Harmanec ,
J. Horn ,
P. Koubský  and
K. Juza
Ž. Ružić
Affiliation:
Hvar Observatory, Zagreb University, Croatia
V. Vujnović
Affiliation:
Hvar Observatory, Zagreb University, Croatia
K. Pavlovski
Affiliation:
Hvar Observatory, Zagreb University, Croatia
H. Božić
Affiliation:
Hvar Observatory, Zagreb University, Croatia
J. R. Percy
Affiliation:
Department of Astronomy, University of Toronto, Canada
A. Attard
Affiliation:
Department of Astronomy, University of Toronto, Canada
P. Harmanec
Affiliation:
Astronomical Institute, Ondřejov, Czech Republic
J. Horn
Affiliation:
Astronomical Institute, Ondřejov, Czech Republic
P. Koubský
Affiliation:
Astronomical Institute, Ondřejov, Czech Republic
K. Juza
Affiliation:
Astronomical Institute, Ondřejov, Czech Republic

Extract

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28 Cyg (V1624 Cyg, HD 191610, HR 7708; B2e, v sin i = 310 km s-1) has been the target of several observational projects, and in 1988 of a large international campaign. This attention was inspired by several photometric studies and especially by the 1985 nearly simultaneous optical and UV spectroscopic monitoring by Peters & Penrod (1988). They found that the line-profile variations were controlled by two frequencies, 1.45 c/d, and 7.43 c/d, which they identified with sectorial pulsations of modes l = 2, m = +2 and l = 10, m = +10. Rapid changes (0.5 to 1 hr) of the CIV wind profile were found; its equivalent width appeared to correlate with the phase of the l = 2 mode. Pavlovski & Ružić (1990) - who independently analysed Hvar 1985 UBV photometry of 28 Cyg - found periodic light variations with a double-wave light curve and a frequency of 1.54 c/d. However – because of the residual scatter around the mean light–curve – the authors tentatively suggested possible multiperiodicity (1.54, 1.33, and 0.95 c/d).

Type
1. Pulsation and Rotation
Information
Symposium - International Astronomical Union , Volume 162: Pulsation, Rotation and Mass Loss in Early-Type Stars , 1994 , pp. 102 - 103
Copyright
Copyright © Kluwer 1994 

References

Bossi, M., Guerrero, A., Zanin, A.: 1993, A&A 269, 343 Google Scholar
Hahula, H., Gies, A.: 1991, BAAS 23, 1379 Google Scholar
Pavlovski, K., Ružić, Ž.: 1990, A&A 236, 393 Google Scholar
Peters, G.J., Penrod, G.D.: 1988, in Decade of UV Astronomy with IUE ESA SP-281, Vol. 2, 117 Google Scholar
Roberts, D.H., Lehar, J., Dreher, J.W.: 1987, AJ 93, 968 Google Scholar