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Abstract In this work, we study the phase-space and chemical properties of the Sagittarius (Sgr) stream, the tidal tails produced by the ongoing destruction of the Sgr dwarf spheroidal (dSph) galaxy, focusing on its very metal-poor (VMP; Fe/H 200 VMP stars. We find the leading arm ( b > 0°) of the Sgr stream to be more metal-poor, by ∼0.2 dex, than the trailing one ( b 2 Gyr ago) have present-day phase-space properties similar to lower metallicity stream stars. Conversely, those stripped more recently ( −1) members of the stream. Such correlation between kinematics and chemistry can be explained by the existence of a dynamically hotter, less centrally concentrated, and more metal-poor population in Sgr dSph prior to its disruption, implying that this galaxy was able to develop a metallicity gradient before its accretion. Finally, we identified several carbon-enhanced metal-poor (C/Fe > +0.7 and Fe/H ≤ −1.5) stars in the Sgr stream, which might be in tension with current observations of its remaining core where such objects are not found.
Limberg et al. (Thu,) studied this question.