The discovery of 8.9s pulsations from the variable X-ray source 2E0050.1-7247 in the small Magellanic cloud

During a systematic search for periodic signals in a sample of ROSAT PSPC light curves, we discovered ~ 8.9s X-ray pulsations in 2E0050.1-7247, a variable X-ray source in the Small Magellanic Cloud. The source was detected several times between 1979 and 1993 at luminosity levels ranging from about 5 times 10^{34} erg/s up to 1.4 times 10^{36} erg/s with both the Einstein IPC and ROSAT PSPC. The X-ray energy spectrum is consistent with a power law spectrum which steepens as the source luminosity decreases. We revealed a pronounced Halpha activity from at least two B stars in the X-ray error circles. These results strongly suggest that the X-ray pulsar 2E0050.1-7247 is in a Be-type massive binary.