A charge-coupled device study of high-latitude Galactic structure: testing the model parameters

Abstract

We interpret published charge-coupled device (CCD) UBVI data to deduce the stellar density distribution and metallicity distribution function in the region of 2-8 kpc from the Galactic plane, and compare our results to several star-count models. A feature of extant star-count models is degeneracy between the adopted scaleheights of the thin and thick discs, and their local normalization. We illustrate the utility of this small data set, and future larger sets (e.g. Sloan Digital Sky Survey, SDSS), by explicitly considering consistency between the derived density laws, and the implied solar neighbourhood luminosity function. Our data set, from Hall et al.'s 1996 paper (l = 52degrees, b =-39degrees), contains 566 stars, selected to be consistent with stellar loci in colour-colour diagrams. The effective apparent V -magnitude interval is 15.5 less than or equal toV (o) less than or equal to 20.5<. Our analysis supports the parametrization of the recent (SDSS) galaxy model of Chen et al., except in preferring the stellar halo axial ratio to be &eta;= 0.84.