Study of the Structure of Interstellar Medium Towards the Star 62 Tau With ESPRESSO Spectrograph

Abstract

We have conducted investigations of the structure of interstellar medium towards the star 62 Tau using a very high resolving power (R = $\lambda /\delta \lambda \sim$170 000) spectrum of ESPRESSO spectrograph. Basic goals of this work are as follows: to search for radial velocity components in the interstellar spectral lines, detectable in the star's spectrum; to measure heliocentric radial velocities (V_r) of the intervening interstellar clouds, to determine Doppler parameter b and the column densities (N) of the atoms and molecules present in the clouds. Using a profile fit procedure we found the components of the atomic and molecular lines with the V_r between $\approx$11–18.5 km s${\hspace{0.17em}}^{-1}$. Only two main radial velocity components for every spectral feature could be discerned confidently. Thus, it was found that the interstellar matter on this sightline is mostly concentrated in the interstellar clouds with V_r $\approx$ 15 and 18 km s${\hspace{0.17em}}^{-1}$. The column densities, yielded with the profile fits are in a good agreement with those found earlier by other researchers. The profiles of the interstellar molecular lines (CN, CH and CH${\hspace{0.17em}}^{+}$) in the star's spectrum were analysed for the first time with such a high resolution.