The S2 Stream: the shreds of a primitive dwarf galaxy

Understand

The S2 stream is a kinematically cold stream that is plunging downwards through the Galactic disc.

• It may be part of a hotter and more diffuse structure called the Helmi stream.
• We present a multi-instrument chemical analysis of the stars in the metal-poor S2 stream using both high- and low-resolution spectroscopy, complemented with a re-analysis of the archival data to give a total sample of 62 S2 members.
• Our high-resolution program provides alpha-elements (C, Mg, Si, Ca and Ti), iron-peak elements (V, Cr, Mn, Fe, Ni), n-capture process elements (Sr, Ba) and other elements such as Li, Na, Al, and Sc for a subsample of S2 objects.