Highlights from the Southern Stellar Stream Spectroscopic Survey
Abstract
Stellar streams, produced by the tidal disruption of dwarf galaxies and globular clusters, yield a snapshot of hierarchical structure formation, and are powerful probes of the mass and profile of the Milky Way's dark matter halo, as well as the formation of its stellar halo. Over the last several years, large imaging surveys have increased the number of known stellar streams to over 60. Spectroscopic follow-up observations are crucial, not only for confirming the nature of the streams, but also for determining their full 6D kinematics, metallicities, orbits, progenitors, and formation histories. The Southern Stellar Stream Spectroscopic Survey (S5) began observing the streams recently discovered by the Dark Energy Survey in 2018, and expanded beyond the DES footprint in 2019. S5 employs the large FoV of AAT and high multiplex of 2dF+AAOmega to obtain kinematic measurements along the spatial extent of the tidal streams. We highlight the most important results from our first observational campaigns, including confirmation of at least seven streams using velocities and metallicities of the members stars. We also report on the serendipitous discovery one of the highest velocity stars in the galaxy, S5-HVS1. This star provides the first direct proof of the Hills Mechanism, in which one star in a binary pair is captured by a supermassive black hole (in this case, Sagittarius A*), while its companion is ejected at extremely high speed.
- Publication:
-
American Astronomical Society Meeting Abstracts #235
- Pub Date:
- January 2020
- Bibcode:
- 2020AAS...23515605K