A New Cold Stream near the Southern Galactic Pole

Abstract

We report the discovery of a cold stream near the southern Galactic pole (dubbed as SGP-S) detected in Gaia Early Data Release 3. The stream is at a heliocentric distance of ∼9.5 kpc and spans nearly 58° by 0.°6 on sky. The color–magnitude diagram of SGP-S indicates an old and metal-poor (age ∼12 Gyr, [M/H] ∼ −2.0 dex) stellar population. The stream’s surface brightness reaches an exceedingly low level of Σ G ≃ 36.2 mag arcsec −2 . Neither extant globular clusters nor other known streams are associated with SGP-S.