Spectroscopic hint of a cold stream in the direction of the globular cluster NGC 1851 Spectroscopic hint of a cold stream in the direction of the globular cluster NGC 1851.

ABSTRACT We present the results of a spectroscopic survey performed in the outskirts of the globular cluster NGC 1851 with VIsible MultiObject Spectrograph (VIMOS)/Very Large Telescope (VLT). The radial velocities of 107 stars in a region between 12 and 33 arcmin around the cluster have been derived. We clearly identify the cluster stellar population over the entire field of view, indicating the presence of a significant fraction of stars outside the tidal radius predicted by King models. We also find tentative evidence of a cold (σ_v ≤ 20 km s⁻¹) peak in the distribution of velocities at v_r ∼ 180 km s⁻¹ constituted mainly by main-sequence stars whose location in the colour-magnitude diagram is compatible with a stream at a similar distance to this cluster. If confirmed, this evidence would strongly support the extragalactic origin of this feature. [ABSTRACT FROM AUTHOR]