THE DIPPING SOURCE X1254-690 OBSERVED WITH GINGA

The results of Ginga observations of the dipping X-ray source X1254-69 0 are presented. The persistent emission spectrum cannot be represente d with conventional two-component models; an additional spectral struc ture, which can be represented either by a broad emission line or by r eflection by warm matter, is required. The energy spectra during dips can be represented by the sum of a non-absorbed component, which has t he same spectral shape as the persistent emissions just before or afte r the dip, and an absorbed component, which is described by the persis tent spectrum with additional absorption. The intensity of the non-abs orbed component first decreases with decreasing intensity; then, the d ecrease saturates at about 8% of the persistent intensity. This strong ly supports the existence of an accretion-disk corona of an electron-s cattering optical depth of about 0.1. The column density of the absorb ed component obtained from spectral fit stays at about 1 x 10(23) cm(- 2) when the intensity of the non-absorbed component is above about 20% of the persistent intensity, but increases to 1 x 10(24) cm(-2) at th e bottom of the dip. The electron-scattering optical depth of the accr etion-disk corona and the column density of the absorber are roughly c onsistent with the double-phase model of X-ray irradiated accretion ma tter.