Chemical abundances of hydrostatic and explosive alpha-elements in
  Sagittarius stream stars
  We analyze chemical abundances of stars in the Sagittarius (Sgr) tidal stream
using high-resolution Gemini+GRACES spectra of 42 members of the highest
surface brightness portions of both the trailing and leading arms. Targets were
chosen using a 2MASS+WISE color-color selection, combined with LAMOST radial
velocities. In this study, we analyze [Fe/H] and alpha-elements produced by
both hydrostatic (O, Mg) and explosive (Si, Ca, Ti) nucleosynthetic processes.
The average [Fe/H] for our Sgr stream stars is lower than that for stars in the
Sgr core, and stars in the trailing and leading arms show systematic
differences in [Fe/H]. Both hydrostatic and explosive elements are depleted
relative to Milky Way (MW) disk and halo stars, with a larger gap between the
MW trend and Sgr stars for the hydrostatic elements. Chemical abundances of Sgr
stream stars show similar patterns to those measured in the core of the Sgr
dSph. We explore the ratio of hydrostatic to explosive alpha-elements
[$\alpha_{\rm h/ex}$] (which we refer to as the "HEx ratio"). Our observed HEx
ratio trends for Sgr debris are deficient relative to MW stars. Via simple
chemical evolution modeling, we show that these HEx ratio patterns are
consistent with a Sgr IMF that lacks the most massive stars. This study
provides a link between the chemical properties in the intact Sgr core and the
significant portion of the Sgr system's luminosity that is estimated to
currently reside in the streams.
