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 distribution functions. 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 similar to 4.5 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).