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Astron. Astrophys. 333, 565-570 (1998)

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6. Conclusions

We have shown that the light variations of R 40 look very much like those seen in other [FORMULA]  Cygni variables and LBVs (at minimum and maximum phase, see van Genderen et al. 1997a,b), another indication that, most likely, all such stars exhibit multi-periodic light variability.

We find evidence that the light variability of R 40 can be separated on the basis of at least 2 frequencies superimposed on a linear trend between JD 2446300 and 2449400. The longest cycle ([FORMULA]   1300 d) represents the SD oscillation (see van Genderen et al. 1997a,b), the shorter cycles describe the microvariations. Note that also for [FORMULA]  Sco such a long cycle of oscillation was found, and that the latter very likely corresponds to an SD phase as well (Sterken et al. 1997). A strong residual scatter remains; as in [FORMULA]  Sco it is the stochastic component of the light variation.

Our work indicates that R 40 provides a direct demonstration (based on contemporaneous highly-accurate data) that the so-called normal SD cycle ([FORMULA] 1300 d) does exist, and that the present bright state is a VLT-SD phase.

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© European Southern Observatory (ESO) 1998

Online publication: April 20, 1998