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SUMMARY:Searching for the fastest stars in Gaia DR2 - Tommaso Marchetti (L
 eiden)
DTSTART:20181130T113000Z
DTEND:20181130T123000Z
UID:TALK110656@talks.cam.ac.uk
CONTACT:Martin Haehnelt
DESCRIPTION:The recent second data release (DR2) of the ESA satellite Gaia
  gives us\nthe first opportunity to search for high velocity stars in the 
 largest stellar\ncatalogue ever produced. Categories of great interest are
  runaway stars\, high velocity halo stars\, and hypervelocity stars (HVSs)
 . In this talk I will present our results on the high velocity tail of the
  velocity distribution of Milky Way stars\, using the subset of about 7 mi
 llion stars with a radial velocity measurement from Gaia DR2. This study r
 eveals the presence of a population of about 20 unbound stars\, half of th
 em with a possible extra-Galactic origin. I will also present ongoing resu
 lts on the data mining routine we specifically developed to search for the
  fastest stars\, HVSs\, in the full (approximately 1.3 billion sources) Ga
 ia DR2 catalogue. Our published estimates show that hundreds to thousands 
 of HVSs are expected to be contained in the full Gaia catalogue\, but thei
 r identification is not trivial because of the missing radial velocity inf
 ormation\, which needs to be obtained with a spectroscopic follow-up. I wi
 ll conclude presenting HVSs as a powerful probe to map the dark halo of th
 e Milky Way: a population of ~100 Gaia HVSs could be used to nail down the
  Galactic halo potential parameters with sub-percent precision.\n
LOCATION:Kavli Large Meeting Room\, Kavli Building
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