부산대학교 도서관

We report preliminary results of the temporal and spectral analysis performed on the X-ray pulsar 4U1538-52 out of eclipse observed by BeppoSAX. We obtain a new estimate of the pulse period of the neutron star P=528.24±0.01 s (corrected for the orbital motion of the X-ray source): the source is still in the spin-up state, as since 1988. The broad band (0.12–100 keV) spectral analysys shows the presence of an absorption feature at ∼21 keV is present, interpreted as due to cyclotron resonant scattering. Another absorption feature at ∼51 keV seems also to be present (at 99% confidence level). If confirmed this might be interpreted as a cyclotron line, but its energy is not compatible with being double than the energy of the first line. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]