BeppoSAX spectroscopy of the NGC 7078 (M 15) globular cluster X-ray sourceX 2127+119

Results of a 1999 November 16-17 BeppoSAX observation of the low-mass X-ray binary X 2127+119 located in the globular cluster M15 are presented. The s ystem is believed to be one where the central neutron star is normally obsc ured by the accretion disk, and only X-rays scattered into our line of sigh t by an extended accretion disk corona (ADC) are observed. The 0.1-10 keV l ightcurve is energy dependent and shows two partial eclipses separated by t he 17.1 hr orbital period. The 0.1-100 keV spectrum is unusually complex, b ut can be successfully modeled using a partially covered power-law and disk -blackbody model. Together with a column consistent with the interstellar v alue to M15, similar to 60% of the source is covered by an additional colum n of similar to 10(22) atom cm(-2). The absorbed component may be X-rays th at pass through the outer layers of the accretion disk. The energy dependen t intensity variations by a factor of similar to 2 may be modeled as due to a changing normalization of the disk-blackbody. None of the other spectral parameters appear to clearly depend on luminosity. The same spectral model is also able to fit an archival ASCA spectrum. We demonstrate that during the luminous (similar to Eddington) X-ray burst observed from X2127+119 by Ginga, material located in the outer regions of the accretion disk could ha ve been temporarily ionized, so allowing the central neutron star to be vie wed directly.