Context :

Aims : We model the broad emission lines present in the optical , UV and X-ray spectra of Mrk 509 , a bright type 1 Seyfert galaxy .
The broad lines were simultaneously observed during a large multiwavelength campaign , using the XMM- Newton -OM for the optical lines , HST-COS for the UV lines and XMM- Newton -RGS and Epic for the X-ray lines respectively .
We also used FUSE archival data for the broad lines observed in the far-ultra-violet .
The goal is to find a physical connection among the lines measured at different wavelengths and determine the size and the distance from the central source of the emitting gas components .

Methods : We used the ” Locally optimally emission Cloud ” ( LOC ) model which interprets the emissivity of the broad line region ( BLR ) as regulated by powerlaw distributions of both gas density and distances from the central source .

Results : We find that one LOC component can not model all the lines simultaneously .
In particular , we find that the X-ray and UV lines likely may originate in the more internal part of the AGN , at radii in the range \sim 5 \times 10 ^ { 14 } -3 \times 10 ^ { 17 } cm , while the optical lines and part of the UV lines may likely be originating further out , at radii \sim 3 \times 10 ^ { 17 } -3 \times 10 ^ { 18 } cm .
These two gas components are parametrized by a radial distribution of the luminosities with a slope \gamma of \sim 1.15 and \sim 1.10 , respectively , both of them covering at least 60 % of the source .
This simple parameterization points to a structured broad line region , with the higher ionized emission coming from closer in , while the emission of the low-ionization lines is more concentrated in the outskirts of the broad line region .

Conclusions :