The characterization of stellar streams in the Milky Way halo can provide important observational constraints on the ΛCDM cosmological model, which posits that galaxies form via the accretion of smaller satellites. One such stream, the 300 km/s stellar stream near the dwarf galaxy Segue 1 (300S), was detected in narrow-field spectroscopic surveys, but its photometric counterpart has not been identified. In this study, we search for members of 300S in wide-field survey data to map out the stream’s extent and further characterize its progenitor. We add to the existing catalog of 300S members by finding new members of 300S in SEGUE-1, SEGUE-2, and APOGEE-2 surveys, and confirm the kinematic association of 300S with an elongated substructure found in both SDSS and PanSTARRS photometric data. The 300S stars display a mean metallicity of [Fe/H] = -1.42 ± 0.26, and have chemical abundance patterns similar to that of Local Group dwarf galaxies, as well as that of the Milky Way halo. Using the open-source code galpy to model a preliminary orbit of the stream, we suggest that the progenitor of 300S experienced one major tidal disruption event on its most recent pericentric passing. We conclude that the progenitor of the stream is a dwarf galaxy that is probably similar to the satellites that were accreted to build the present-day Milky Way halo.
American Astronomical Society Meeting Abstracts #231
- Pub Date:
- January 2018