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SUMMARY:Tagging and Tracing Globular Cluster-Origin Stars from the Early M
 ilky Way with Gaia - Sarah Kane / IoA
DTSTART:20241113T131500Z
DTEND:20241113T134000Z
UID:TALK224479@talks.cam.ac.uk
CONTACT:Xander Byrne
DESCRIPTION:Globular clusters (GCs) are sites of extremely efficient star 
 formation\, and recent studies suggest they significantly contributed to t
 he early Milky Way's stellar mass build-up. Although their role has since 
 diminished\, GCs' impact on the Galaxy's initial evolution can be traced t
 oday by identifying their most chemically unique stars—those with anomal
 ous nitrogen and aluminum overabundances and oxygen depletion. While they 
 are a perfect tracer of clusters\, be it intact or fully dissolved\, these
  high-[N/O]\, high-[Al/Fe] GC-origin stars are extremely rare within the c
 urrent Galaxy. To address the scarcity of these unusual\, valuable former 
 GC members\, we train a neural network (NN) to identify high-[N/O]\, high-
 [Al/Fe] stars using low-resolution Gaia BP/RP spectra. Our NN achieves a c
 lassification accuracy of approximately 99% and a false positive rate of a
 round 7%\, identifying 878 new candidates in the Galactic field. We valida
 te our results with several physically-motivated sanity checks\, showing\,
  for example\, that the incidence of selected stars in Galactic GCs is sig
 nificantly higher than in the field. Moreover\, we find that most of our G
 C-origin candidates reside in the inner Galaxy\, having likely formed in t
 he proto-Milky Way\, consistent with previous research. The fraction of GC
  candidates in the field drops at a metallicity of [Fe/H]=-1\, approximate
 ly coinciding with the completion of spin-up\, i.e. the formation of the G
 alactic stellar disk.
LOCATION:The Hoyle Lecture Theatre + Zoom 
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