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Astron. Astrophys. 332, 149-154 (1998)

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4. Fitting the whole data set

In this section we summarize in one equation, able to reproduce the real set of data shown in Fig. 1, the results here described. We assume that the star oscillates between two states of activity: on and off. The step function is assumed to have a period of 158.7 days. During the off state the flux is assumed to be 40 mJy. During the on state (phase 0.5-1.1) the emission is modulated as:


where [FORMULA] with [FORMULA] JD (Carlos and Popper 1971).

The shadowing due to the star rotation has also been taken into account by reducing the flux to 40 mJy whenever in excess of this value. The crosses in Fig. 1 correspond to phases 0.35-0.45 of the orbital period.

It appears from Fig. 1 that the computed curve fits the data points remarkably well, reproducing the time of occurrence of all flares above 250 mJy. Of course the intensity of each flare cannot be reproduced by this type of fit as it depends on many unpredictable variables, such the magnetic field strength in each loop and its orientation with respect to the observer, the number and the energy spectrum of the emitting particles, etc.

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© European Southern Observatory (ESO) 1998

Online publication: March 10, 1998