The analysis of the 34 short-period variable stars in Cen stressed the importance of studying the Fourier parameters. The sample of high-amplitude Sct and SX Phe stars is considerably enlarged by these new variables especially toward shortest periods. In general, many variable stars show a very small amplitude, below 0.10 mag. Such a small value is probably responsible for the high number of sinusoidal light curves: since the ratios are usually around 0.1, the amplitude of the term is very small and observational errors can mask the asymmetry of the light curve.
In spite of that, the parameters are confined in a narrow strip for periods between 0.042 d and 0.07 d. Toward longer periods, there is an overlapping with the values obtained in the case of galactic stars. Toward shorter periods, the tendency to decreasing values is also verified. It should be noted that there is a strong difference with the results obtained by analyzing the stars in the Carina dwarf Spheroidal Galaxy (Poretti 1999), where the distribution is not as clear as it is here.
As a general consideration, the progression of the parameter as a function of the period appears in a clear way. However, a careful analysis should take more details in consideration:
It is of paramount importance to obtain very accurate light curves to give more confidence to these results. However, it should be noted that the and values (Table 1) supply a good confirmation of the reliability of the least-squares fits: indeed, their mean values (1.20 rad and 5.18 rad, respectively) are in excellent agreement with the expected ones on the basis of the results on the galactic variables (see Fig. 2 in Antonello et al. 1986, upper and middle panels).
© European Southern Observatory (ESO) 1999
Online publication: May 21, 1999