Analysis of UBV Photometry in Selected Area 133

Abstract

We interpret the de-reddened UBV data for the field SA 133 to deduce the stellar density and metallicity distributions function. The logarithmic local space density for giants, $D^{*}(0)=6.40$, and the agreement of the luminosity function for dwarfs and sub-giants with the one of Hipparcos confirms the empirical method used for their separation. The metallicity distribution for dwarfs gives a narrow peak at [Fe/H]=+0.13 dex, due to apparently bright limiting magnitude, $V_{o}=16.5$, whereas late-type giants extending up to $z \sim4.5$ kpc from the galactic plane have a multimodal distribution. The metallicity distribution for giants gives a steep gradient $d[Fe/H]/dz=-0.75$ dex kpc$^{-1}$ for thin disk and thick disk whereas a smaller value for the halo, i.e. $d[Fe/H]/dz=-0.45$ dex kpc$^{-1}$.