XMM-Newton EPIC and OM Observations of Her X-1 over the 35 d Beat Period   and an Anomalous Low State
  We present the results of a series of XMM-Newton EPIC and OM observations of Her X-1, spread over a wide range of the 35 d precession period. We confirm that the spin modulation of the neutron star is weak or absent in the low state - in marked contrast to the main or short-on states. The strong fluorescence emission line at ~6.4 keV is detected in all observations (apart from one taken in the middle of eclipse), with higher line energy, width and normalisation during the main-on state. In addition, we report the detection of a second line near 7 keV in 10 of the 15 observations taken during the low-intensity states of the system. We discuss these observations in the context of previous observations, investigate the origin of the soft and hard X-rays and consider the emission site of the 6.4keV and 7keV emission lines. 
S. Zane (1), G. Ramsay (1), M. A. Jimenez-Garate (2), J. W. den Herder   (3), M. Still (4), P.T. Boyd (4), C. J. Hailey (5) ...