An Investigation Into the Nature of the 4.4-HOUR Periodic Source 4U1755-33
Parmar, A. N.; White, N. E.; Mason, K. O.; Sztajno, M.
Germany, United Kingdom
Abstract
We present the results of a continuous 18 hour observation of 4U1755-33 made with the European Space Agency's EXOSAT Observatory. Four 50 min dips in X-ray intensity were observed equally spaced with a period of 4.4 hrs, confirming the periodicity first suggested in White et al. (1984). The dips are spectrally independent. We examine the properties of 4U1755-33 and conclude that the source is most probably point-like and that the metallicity of the absorbing material is at least 600 times less than cosmic values.