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Astron. Astrophys. 340, 149-159 (1998)

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Pulsation, binarity and close frequency spacing in [FORMULA] Scuti stars: BQ and BW Cancri

Results of the STEPHI VI campaign in Praesepe Cluster

M. Alvarez 1, M.M. Hernández 2, E. Michel 3, S.Y. Jiang 4, J.A. Belmonte 2, M. Chevreton 5, G. Massacrier 3, Y.Y. Liu 4, Z.P. Li 4, M.J. Goupil 3, T. Roca Cortés 2, A. Mangeney 6, N. Dolez 7, J.C. Valtier 8, I. Vidal 2, M. Sperl 9 and S. Talon 3

1 Instituto de Astronomía - UNAM, Ap.P. 877, Ensenada, BC, México
2 Instituto de Astrofísica de Canarias, E-38200 La Laguna, Tenerife, Spain
3 Observatoire de Paris-Meudon, DASGAL, URA CNRS 335, F-92195 Meudon, France
4 Beijing Observatory, Chinese Academy of Sciences, Beijing, P.R. China
5 Observatoire de Paris-Meudon, DAEC, F-92195 Meudon, France
6 Observatoire de Paris-Meudon, DESPA, F-92195 Meudon, France
7 Observatoire Midi-Pyrénées, F-31400 Toulouse, France
8 Observatoire de la Côte d'Azur, Université de Nice, F-06034 Nice, France
9 Institut für Astronomie, A-1180 Vienna, Austria

Received 2 February 1998 / Accepted 10 September 1998


New pulsation modes in two [FORMULA] Scuti stars of Praesepe cluster, BQ and BW Cnc, have been detected during the STEPHI VI campaign in 1995. In particular, 3 frequencies for BQ Cnc and 9 frequencies for BW Cnc have been found above a 99% confidence level. The possibility of the presence of a g-mode present in BQ Cnc is discussed, considering its binarity. The effect of mutual interference between very close detected frequencies in BW Cnc during the observations, is also considered. This last effect reveals the necessity of long-period observing runs, in order to avoid its influence in the final number of detected modes. In such situation, studies of secular amplitude changes can be strongly affected.

Key words: stars: oscillations – stars: variables: ffi Sct – stars: individual: BQ Cnc – stars: individual: BW Cnc

Send offprint requests to: M. Alvarez, PO.Box 439027, San Ysidro, CA 92143-9027, USA (alvarez@bufadora.astrosen.unam.mx)

© European Southern Observatory (ESO) 1998

Online publication: November 3, 1998