Delta Scuti stars in Praesepe I. The STACC 1998 campaign - The photometry

S. Frandsen, J. Nuspl, A. Pigulski, M. Breger, J. A. Belmonte, T. Dall, T. Arentoft, C. Sterken, T. Medupe, S. K. Gupta, F. J. G. Pinheiro, M. J. P. F. G. Monteiro, C. Barban, M. Chevreton, E. Michel, J. M. Benko, Sz. Barcza, R. Szabó, Z. Kołaczkowski, G. Kopacki, S. N. Udovichenko

We present the results of the multisite differential CCD photometry for the two delta Scuti stars, BN and BV Cnc, in the open cluster Praesepe. The main objective was to identify the character of the pulsation modes in BN Cnc deriving their accurate periods, amplitudes and phases. These parameters are essential for the mode identification which uses combined photometric and spectroscopic data and is presented in the second article. For BN Cnc, six pulsation modes with amplitudes above the detection limit ( ~ 0.5 mmag) were detected. Using the same CCD frames it was possible to verify the presence of the four pulsation modes in BV Cnc, the faintest of delta Scuti stars in Praesepe. It is shown that in this very low-amplitude pulsator, substantial amplitude variations are seen between 1997 and 1998. Based in part on observations obtained at the European Southern Observatory at La Silla, Chile (Application 60D-0148).

Astronomy and Astrophysics
Volume 376, Page 175
September 2001

DOI: 10.1051/0004-6361:20010950