Profiles of Interstellar Spectral Features Caused by Physical Parameters of Clouds

The disk of our Galaxy is filled with clouds of diffuse matter, modifying spectra of distant stars. These clouds are sources of extinction, polarization and of spectral features such as atomic and molecular lines as well as the diffuse interstellar bands (DIBs), still of unknown origin, though likely molecular. Apparently physical parameters of individual translucent clouds are various. We try to provide some constraints on theoretical models of translucent interstellar clouds. It is demonstrated that intensities and profile details of DIBs can be determined using the ESPRESSO spectrograph fed by VLT. This possibility follows its very high resolution and signal-to-noise ratio, necessary to analyze atomic and molecular features, detectable in spectra of OB-stars, and originated in single (thus - likely optically thin) interstellar clouds. Our set of five high resolution (lambda/delta lambda, = 140000) ESPRESSO spectra of hot, reddened stars allows us to analyze profiles of some DIBs. It is argued that more high quality spectra from ESPRESSO are necessary to identify the DIB cariers.