The browser you are using is not supported by this website. All versions of Internet Explorer are no longer supported, either by us or Microsoft (read more here: https://www.microsoft.com/en-us/microsoft-365/windows/end-of-ie-support).

Please use a modern browser to fully experience our website, such as the newest versions of Edge, Chrome, Firefox or Safari etc.

Thomas Bensby. Profile photo.

Thomas Bensby

Senior lecturer

Thomas Bensby. Profile photo.

A First Constraint on the Thick Disk Scale Length: Differential Radial Abundances in K Giants at Galactocentric Radii 4, 8, and 12 kpc

Author

  • Thomas Bensby
  • A. Alves-Brito
  • M. S. Oey
  • D. Yong
  • J. Melendez

Summary, in English

Based on high-resolution spectra obtained with the MIKE spectrograph on the Magellan telescopes, we present detailed elemental abundances for 20 red giant stars in the outer Galactic disk, located at Galactocentric distances between 9 and 13 kpc. The outer disk sample is complemented with samples of red giants from the inner Galactic disk and the solar neighborhood, analyzed using identical methods. For Galactocentric distances beyond 10 kpc, we only find chemical patterns associated with the local thin disk, even for stars far above the Galactic plane. Our results show that the relative densities of the thick and thin disks are dramatically different from the solar neighborhood, and we therefore suggest that the radial scale length of the thick disk is much shorter than that of the thin disk. We make a first estimate of the thick disk scale length of L-thick = 2.0 kpc, assuming L-thin = 3.8 kpc for the thin disk. We suggest that radial migration may explain the lack of radial age, metallicity, and abundance gradients in the thick disk, possibly also explaining the link between the thick disk and the metal-poor bulge.

Department/s

  • Lund Observatory

Publishing year

2011

Language

English

Publication/Series

Astrophysical Journal Letters

Volume

735

Issue

2

Document type

Journal article

Publisher

IOP Publishing

Topic

  • Astronomy, Astrophysics and Cosmology

Keywords

  • Galaxy: abundances
  • Galaxy: disk
  • Galaxy: evolution
  • Galaxy: formation
  • Galaxy: stellar content
  • stars: abundances

Status

Published

ISBN/ISSN/Other

  • ISSN: 2041-8213