Confirming chemical clocks: asteroseismic age dissection of the Milky Way disk(s)

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  • Victor Silva Aguirre
  • Mathias Bojsen-Hansen,
  • Ditte Slumstrup
  • L. Casagrande, Australian National University, AustraliaD. Kawata, University College London, United KingdomI. Ciucá, University College London, United Kingdom
  • Rasmus Handberg
  • Mikkel Nørup Lund
  • Jakob Rørsted Mosumgaard
  • Daniel Huber, University of Hawaii, University of Sydney, J. A. Johnson, Ohio State University, United StatesM. H. Pinsonneault, Ohio State University, United StatesA. M. Serenelli, Instituto de Ciencias del Espacio (ICE-CSIC/IEEC), Spain
  • Dennis Stello
  • J. Tayar, Ohio State University, United StatesJ. C. Bird, Vanderbilt University, United StatesS. Cassisi, INAF-Astronomical Observatory of Teramo, ItalyM. Hon, University of New South Wales, AustraliaM. Martig, Liverpool John Moores University, United Kingdom
  • Poul Erik Nissen
  • H. W. Rix, Max-Planck-Institut für Astronomie, GermanyR. Schönrich, University of Oxford , United KingdomC. Sahlholdt, W. H. Trick, Max-Planck-Institut für Astronomie, GermanyJ. Yu, University of Sydney, Aarhus University
Investigations of the origin and evolution of the Milky Way disk have long relied on chemical and kinematic identification of its components to reconstruct our Galactic past. Difficulties in determining precise stellar ages have restricted most studies to small samples, normally confined to the solar neighbourhood. Here we break this impasse with the help of asteroseismic inference and perform a chronology of the evolution of the disk throughout the age of the Galaxy. We chemically dissect the Milky Way disk population using a sample of red giant stars spanning out to 2 kpc in the solar annulus observed by the Kepler satellite, with the added dimension of asteroseismic ages. Our results reveal a clear difference in age between the low- and high-α populations, which also show distinct velocity dispersions in the V and W components. We find no tight correlation between age and metallicity nor [α /Fe] for the high-α disk stars. Our results indicate that this component formed over a period of more than 2 Gyr with a wide range of [M/H] and [α /Fe] independent of time. Our findings show that the kinematic properties of young α-rich stars are consistent with the rest of the high-α population and different from the low-α stars of similar age, rendering support to their origin being old stars that went through a mass transfer or stellar merger event, making them appear younger, instead of migration of truly young stars formed close to the Galactic bar.
Original languageEnglish
JournalMonthly Notices of the Royal Astronomical Society
Volume475
Issue number4
Pages (from-to)5487-5500
Number of pages14
ISSN0035-8711
DOIs
StatePublished - 2018

    Research areas

  • Galaxy: disc, Galaxy: evolution, Galaxy: structure, Asteroseismology, stars: fundamental parameters, stars: kinematics and dynamics

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