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Astron. Astrophys. 331, 934-948 (1998)

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6. Summary and outlook

In the present paper, we have developped and tested a comprehensive computer algorithm for the statistical analysis of three-color star count data. This algorithm has been applied to the first-half sample of the new catalog of homogeneous RGU data in seven fields of the Basel high-latitude survey in order to determine optimized parameter values and constraints for models of the density, luminosity, and metallicity distributions of the Galactic field star populations. While our first results confirm that the new data indeed allow us to derive density and metallicity structures which are, by and large, consistent with currently accepted values for all major stellar components of the Galaxy, they also indicate that, due to their high statistical weight, the present new survey data may also carry the potential for deriving the large-scale properties of the thick disk with higher confidence than before. Thus, the evidence for the thick disk component will be exposed in greater detail in Paper II of this series, in particular by expanding our studies of the luminosity function and the metallicity distribution.

Beginning with Paper V, we shall provide more definitive results based on the analysis of the complete survey data in all 14 Basel fields, and taking advantage of further extended and improved RGU system calibrations expected from the new synthetic photometry data base constructed by Lejeune et al. (1997a,b). This will, finally, also allow us to assess the significance of the results derived from the present project in terms of comprehensive comparisons with independent studies of the Galactic density and/or chemical abundance distributions from both multiple-field (e.g., Gould et al. 1993, Ojha et al. 1994a,b, Robin et al. 1996, Soubiran 1993) and unidirectional high-latitude surveys, e.g., in SA 57 [North Galactic Pole] (Chen 1997, Reid & Majewski 1993, Spagna et al. 1996), SA 94 (Friel & Cudworth 1986), M5 (Perrin et al. 1995), and SA 54 (Yamagata & Yoshii 1992).

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© European Southern Observatory (ESO) 1998

Online publication: March 3, 1998