2006A&A...448..817D

We report on a simultaneous Chandra and RossiXTE observation of the low-mass X-ray binary atoll bursting source MXB 1728-34 performed on 2002 March 3-5. We fit the 1.2-35keV continuum spectrum with a blackbody plus a Comptonized component. Large residuals at 6-10keV can be fitted by a broad (FWHM≃2keV) Gaussian emission line or, alternatively, by two absorption edges associated with lowly ionized iron and Fe XXV/XXVI at ∼7.1keV and ∼9keV, respectively. In this interpretation, we find no evidence of broad emission lines between 6 and 7keV. We test our alternative model of the iron K shell region by reanalysing a previous BeppoSAX observation of MXB 1728-34, finding a general agreement with our new spectral model.