A 1700 km/s Hyper Velocity Star discovered by the Southern Stellar Stream Spectroscopic Survey

  • Sept. 9, 2019, 2:00 pm
  • Curia II
  • Ting Li, Carnegie Observatories

In this talk, I will present an ongoing spectroscopic program, the Southern Stellar Stream Spectroscopic Survey (S5), which maps these southern streams with the fiber-fed AAOmega spectrograph on the Anglo-Australian Telescope. S5 is the first systematic program pursuing a complete census of known streams in the southern hemisphere. In additional to observing stars in the stellar streams, we use the extra fibers to conduct two auxiliary programs, a Milky Way halo survey as well as a low redshift galaxy survey. In particular, we serendipitously discovered the fastest Main Sequence hyper-velocity star (HVS), S5-HVS1, from the auxiliary Milky Way halo program. This star, moving at ~1700 km/s, was kicked away from Milky Way’s super massive black hole, Sgr A*, 4.8 Myr ago. It is so far the only HVS confidently associated with the Galactic Centre.