EDP Sciences
Free access
Volume 433, Number 1, April I 2005
Page(s) 241 - 245
Section Interstellar and circumstellar matter
DOI http://dx.doi.org/10.1051/0004-6361:20042127

A&A 433, 241-245 (2005)
DOI: 10.1051/0004-6361:20042127

A search for interstellar absorptions towards Sgr dSph

S. Monai1, P. Bonifacio1 and L. Sbordone2, 3

1  Istituto Nazionale di Astrofisica - Osservatorio Astronomico di Trieste, via Tiepolo 11 34131 Trieste, Italy
    e-mail: monai@ts.astro.it
2  European Southern Observatory, Casilla 19001, Santiago, Chile
3  Università di Roma 2 "Tor Vergata", via della Ricerca Scientifica, Rome, Italy

(Received 6 October 2004 / Accepted 3 December 2004 )

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 8.2 m 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 43 000, i.e.  7  $\mathrm {km\,s}^{-1}$, which allows an exploratory study. We detected two distinct groups of IS absorptions, a "local" group, with radial velocities ranging from -43  $\mathrm {km\,s}^{-1}$ to 50  $\mathrm {km\,s}^{-1}$, and a high velocity group with radial velocities ranging from 150 km s-1 to 165 km s-1. 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$\farcm$5 in the sky. We argue that the observations suggest a stripping of gas due to the passage of Sgr through the Galactic disc.

Key words: galaxies: clusters: individual: Terzan 7 -- ISM: general -- ISM: clouds -- ISM: kinematics and dynamics

SIMBAD Objects

© ESO 2005