2001A&A...378..466O

We report the detection of short period oscillations in the sdB stars HS0039+4302, HS0444+0408, HS1824+5745 and HS2151+0857 from time-series photometry made at the Nordic Optical Telescope (NOT) of a sample of 55 candidates. Hence these four hot subdwarfs are new members of the EC14026 class of pulsating sdB stars. HS0039+4302 is a multi-mode pulsator with at least four distinct periods in the range between 182 and 234s, and amplitudes up to 8mma. HS0444+0408 shows one dominant pulsation at 137s (A∼12mma) and a second weaker pulsation at 170s (A∼3mma). For HS1824+5745 we find a single period of 139s with an amplitude of about 5mma. HS2151+0857 shows four periods in the range 129-151 s with amplitudes between 2 and 5mma. Our NLTE model atmosphere analysis of the time-averaged optical spectra place all stars well within the theoretical sdBV instability strip.