EXOSAT Observations of the Globular Cluster X-ray Sources X0512-401 and X1745-203

Abstract

The authors observed X0512-401 with the Exosat LE and ME and present here the results of the spectral analysis made of the data. The spectral model best fitting the combined LE and ME data is a single thermal Bremsstrahlung. A single blackbody model is excluded by these observations. A power-law is generally a worse representation of the data than a thermal spectrum. Neither a two-component power-law nor a two-component blackbody + thermal Bremsstrahlung model provides a better fit than a single thermal + Gaunt model. These results are interpreted as evidence that X0512-401 is a member of a low-mass X-ray binary system with an unevolved companion. The authors also observed X1745-203 with Exosat but did not detect it. X1745-203 is confirmed to be a transient X-ray source in view of Exosat and previous observations.