The structure of the outer Galactic disc as revealed by IPHAS early A stars

S. E. Sale*, J. E. Drew, C. Knigge, A. A. Zijlstra, M. J. Irwin, R. A. H. Morris, S. Phillipps, J. J. Drake, R. Greimel, Y. C. Unruh, P. J. Groot, A. Mampaso, N. A. Walton

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)

27 Citations (Scopus)
294 Downloads (Pure)

Abstract

This study is an investigation of the stellar density profile of the Galactic disc in the anticentre direction. We select over 40 000 early A stars from INT/WFC Photometric Ha Survey of the Northern Galactic Plane (IPHAS) photometry in the Galactic longitude range 160 degrees <l <200 degrees close to the equatorial plane (-1 degrees <b <+1 degrees). We then compare their observed reddening-corrected apparent magnitude distribution with simulated photometry obtained from parametrized models in order to set constraints on the anticentre stellar density profile. By selecting A stars, we are appraising the properties of a population only similar to 100 Myr old. We find that the stellar density profile of young stars is well fit to an exponential with length-scale of (3020 +/- 120(statistical) +/- 180(systematic)) pc, which is comparable to that obtained in earlier studies, out to a Galactocentric radius of R(T) = (13.0 +/- 0.5(statistical) +/- 0.6(systematic)) kpc. At larger radii, the rate of decline appears to increase with the scalelength dropping to (1200 +/- 300(statistical) +/- 70(systematic)) pc. This result amounts to a refinement of the conclusions reached in previous studies that the stellar density profile is abruptly truncated. The IPHAS A star data are not compatible with models that propose a sudden change in metallicity at R(G) = 10 kpc.

Original languageEnglish
Pages (from-to)713-723
Number of pages11
JournalMonthly Notices of the Royal Astronomical Society
Volume402
Issue number2
DOIs
Publication statusPublished - 21 Feb 2010

Bibliographical note

11 pages, accepted for publication in MNRAS

Keywords

  • surveys
  • Galaxy: abundances
  • Galaxy: disc
  • Galaxy: stellar content
  • Galaxy: structure
  • OLD OPEN CLUSTERS
  • ON SPIRAL GALAXIES
  • H-ALPHA SURVEY
  • MILKY-WAY
  • CHEMICAL EVOLUTION
  • METALLICITY GRADIENT
  • ABUNDANCE GRADIENT
  • SOLAR NEIGHBORHOOD
  • SURFACE-BRIGHTNESS
  • YOUNG STARS

Fingerprint Dive into the research topics of 'The structure of the outer Galactic disc as revealed by IPHAS early A stars'. Together they form a unique fingerprint.

Cite this