Delta Scuti Star Newsletter

Issue 6, May 1993

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The Delta Scuti star BI CMi (=HD 66853): pulsational behaviour and a critical discussion of physical parameter determination.

by: L.Mantegazza, E.Poretti

A two site photometric campaigne on the d Scuti star BI CMi (2302 V observations over 16 nights) has allowed us to detect unambiguously four pulsation frequencies (f1 = 8.246, f2 = 8.865, f3 = 7.433 and f4 = 8.515 c/d) with amplitudes between 22 and 5 mmag. The data also show the presence of the nonlinear coupling term f1 + f2, the 2f2 term and possible presence of two other frequencies with amplitudes of 2 - 3 mmag. Other components with further smaller amplitudes are probably present, but the data do not allow reliable identifications. We discuss the identifications of the pulsation modes in terms of nonradial p modes, and we also point out the uncertainties in these identification associated to the physical parameter estimates.

The possible microvariability of HD 67028, one of the two comparison stars, is also discussed.