The Millennium Galaxy Catalogue: star counts and the structure of the Galactic stellar halo

DJ Lemon, Rosemary FG Wyse, J Liske, Simon Peter Driver, Keith Douglas Horne

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)

Abstract

We derive a star catalogue generated from the images taken as part of the similar to37.5 deg(2) Millennium Galaxy Catalogue. These data, alone and together with colours gained from the Sloan Digital Sky Survey Early Data Release, allow the analysis of faint star counts (B-MGC<20) at high Galactic latitude (41&DEG;<b<63&DEG;), as a function of Galactic longitude (239&DEG;<l<353&DEG;). We focus here on the inner stellar halo, providing robust limits on the amplitude of substructure and on the large-scale flattening. In line with previous results, the thick disc, an old, intermediate-metallicity population, is clearly seen in the colour-magnitude diagram. We find that the Galactic stellar halo within &SIM;10 kpc (the bulk of the stellar mass) is significantly flattened, with an axial ratio of (c/a)=0.56&PLUSMN;0.01, again consistent with previous results. Our analysis, using counts-in-cells, angular correlation functions and the Lee 2D statistic, confirms tidal debris from the Sagittarius dwarf but finds little evidence for other substructure in the inner halo, at heliocentric distances of &LSIM;5 kpc. This new quantification of the smoothness in coordinate space limits the contribution of recent accretion/disruption to the build-up of the bulk of the stellar halo.

Original languageEnglish
Pages (from-to)1043-1054
Number of pages12
JournalMonthly Notices of the Royal Astronomical Society
Volume347
Issue number3
Publication statusPublished - 1 Feb 2004

Keywords

  • astronomical data bases : miscellaneous
  • catalogues
  • Galaxy : halo
  • Galaxy : structure
  • DIGITAL SKY SURVEY
  • ANGULAR-CORRELATION FUNCTION
  • SAGITTARIUS DWARF GALAXY
  • MILKY-WAY
  • FAINT STARS
  • THICK DISK
  • DENSITY DISTRIBUTION
  • LUMINOSITY FUNCTION
  • SUBSTRUCTURE
  • EVOLUTION

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