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

    Research output: Contribution to journalArticlepeer-review


    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 Hα Survey of the Northern Galactic Plane (IPHAS) photometry in the Galactic longitude range 160° <l <200° close to the equatorial plane (-1° <b <+1°). 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 ∼100 Myr old. We find that the stellar density profile of young stars is well fit to an exponential with length-scale of (3020 ± 120statistical ± 180systematic) pc, which is comparable to that obtained in earlier studies, out to a Galactocentric radius of RT = (13.0 ± 0.5statistical ± 0.6systematic) kpc. At larger radii, the rate of decline appears to increase with the scalelength dropping to (1200 ± 300statistical ± 70systematic) 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 RG = 10 kpc. © 2009 The Authors. Journal compilation © 2009 RAS.
    Original languageEnglish
    Pages (from-to)713-723
    Number of pages10
    JournalMonthly Notices of the Royal Astronomical Society
    Issue number2
    Publication statusPublished - Feb 2010


    • Galaxy: abundances
    • Galaxy: disc
    • Galaxy: stellar content
    • Galaxy: structure
    • Surveys


    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