We report on a 300 ks BeppoSAX ( 0.12–200 keV ) observation of Circinus X–1 ( Cir X–1 ) at phases between 0.62 and 0.84 and on a 90 ks BeppoSAX observation of Cir X–1 at phases 0.11–0.16 .
Using the canonical model adopted until now to fit the energy spectrum of this source large residuals appear below 1 keV .
These are well fitted using an equivalent hydrogen column of 0.66 \times 10 ^ { 22 } cm ^ { -2 } , adding absorption edges of O vii , O viii and Ne ix in the spectra extracted from the observation at phases 0.62–0.84 and adding absorption edges of O vii , O viii , Mg xi and Mg xii and absorption lines of O viii and Mg xii in the spectra extracted from the observation at phases 0.11–0.16 .
During the observation at phases 0.62–0.84 the electron density associated to the ionized matter is \sim 10 ^ { 13 } cm ^ { -3 } remaining quite constant going away from the compact object .
During the observation at phases 0.11–0.16 the electron density profile varies along the distance going from \sim 6 \times 10 ^ { 13 } cm ^ { -3 } at \sim 10 ^ { 11 } cm to \sim 9 \times 10 ^ { 10 } cm ^ { -3 } at \sim 10 ^ { 13 } cm .
The equivalent hydrogen column towards Cir X–1 is three times lower than the value obtained from previous models .
This low value would imply that Cir X–1 is at a distance of 4.1 kpc .