2005A&A...433..241M

We searched for Na I D1, D2 interstellar absorption lines towards 12 giant stars of the Sgr dwarf spheroidal and 3 stars of the associated globular cluster Terzan 7, observed at high resolution with the UVES spectrograph at the 8.2m Kueyen VLT telescope. These stars are not an ideal background source for the analysis of interstellar (IS) absorption lines since they have been observed in the framework of a stellar abundances study. However they are sufficiently luminous to allow a decent S/N ratio at a resolution of about 43000, i.e. 7km/s, which allows an exploratory study. We detected two distinct groups of IS absorptions, a ``local'' group, with radial velocities ranging from -43km/s to 50km/s, and a high velocity group with radial velocities ranging from 150km/s to 165km/s. Likely the high velocity components are due to gas falling on the Sgr dSph since they have been observed only in 2 stars which are separated by only 1.5' in the sky. We argue that the observations suggest a stripping of gas due to the passage of Sgr through the Galactic disc.