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Title: THE DOMINANT EPOCH OF STAR FORMATION IN THE MILKY WAY FORMED THE THICK DISK

We report the first robust measurement of the Milky Way star formation history using the imprint left on chemical abundances of long-lived stars. The formation of the Galactic thick disk occurs during an intense star formation phase between 9.0 (z ∼ 1.5) and 12.5 Gyr (z ∼ 4.5) ago and is followed by a dip (at z ∼ 1.1) lasting about 1 Gyr. Our results imply that the thick disk is as massive as the Milky Way's thin disk, suggesting a fundamental role of this component in the genesis of our Galaxy, something that had been largely unrecognized. This new picture implies that huge quantities of gas necessary to feed the building of the thick disk must have been present at these epochs, in contradiction with the long-term infall assumed by chemical evolution models in the last two decades. These results allow us to fit the Milky Way within the emerging features of the evolution of disk galaxies in the early universe.
Authors:
; ; ; ;  [1] ;  [2] ;  [3]
  1. Observatoire de Paris, GEPI, CNRS, Université Paris Diderot, 5 Place Jules Janssen, F-92190 Meudon (France)
  2. Institut d'Astrophysique de Paris, UMR 7095, CNRS, Université Pierre et Marie Curie, 98 bis Bd Arago, F-75005 Paris (France)
  3. Observatoire de Paris, LERMA, CNRS, 61 Avenue de l'Observatoire, F-75014 Paris (France)
Publication Date:
OSTI Identifier:
22364015
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 781; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCRETION DISKS; GALACTIC EVOLUTION; MILKY WAY; ORIGIN; STAR EVOLUTION; STARS; UNIVERSE