SIMBAD references

The results of two runs of time-series photometry made at the Nordic Optical Telescope clearly show that the sdB star PG1618+563B is a new member of the EC14026 class of sdB pulsators. Its power spectrum shows a doublet of frequencies at about 6.95 and 7.18 mHz (P∼144 and 139 s respectively), which produce a modulation effect in the light curve with a beat period of about 1.2 hours. The amplitudes of the two signals are very low, not more than 2 mma. Thanks to its brightness (B=13.4), which makes PG1618+563B one of the brightest objects of its class, we were able to observe the star also in different colours and measure its UBV pulsation amplitudes and phases. The comparison of these ``nonadiabatic observables'' with models may help the identification of the oscillation modes. The spectral analysis of the sdB star and the spectral classification of PG1618+563A suggest that both stars form a wide visual binary (∼2500 A.U. separation), at a distance of about 680 pc from the sun.