Speaker
Description
Providing a detailed picture of the complexity of the Sagittarius stream is an important aspect of investigating the outer Galactic halo and constraining the Milky Way potential. Several attempts have been made to model the complex structure of the Sagittarius stream. However, no model has yet been able to match all the intricate features observed for the stream, including for instance a bifurcation and several wraps. Most recently, it was discovered that the stream also has a very distant spur feature at least out to ~120 kpc (Sesar et al., 2017).
The aim of this work is to characterize this Sagittarius stream spur using blue horizontal branch stars, one of the few standard candle tracers reaching these outer realms of the Milky Way. Blue horizontal branch candidates were selected using a unique combination of narrow- and broad-band photometry as well as Gaia astrometry. Follow-up optical spectra are obtained using ESO/FORS2. The sample allows us to trace the structure to even larger distances. The observed radial velocities of these stars discriminate different model predictions for the origin of this mysterious spur feature.
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