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

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The new Basel high-latitude field star survey of the Galaxy

I. General introduction, methodology and first analysis

Roland Buser 1, Jianxiang Rong 2 and Salih Karaali 3

1 Astronomisches Institut der Universität Basel, Venusstr. 7, CH-4102 Binningen, Switzerland
2 Astronomy Department, Nanjing University, Nanjing 210008, P.R. China
3 Istanbul University Science Faculty, Department of Astronomy and Space Sciences, TR-34452 University - Istanbul, Turkey

Received 1 August 1997 / Accepted 10 November 1997


This is the first in a series of papers devoted to the determination of Galactic structure from the new homogeneous catalog of photographic RGU field star data in fourteen high-latitude directions. We give a general description of the motivation for this work, the construction of the observational data base, and the structural Galaxy models designed for its analysis. In particular, we provide a concise yet comprehensive account of the statistical methodology used for determining reliable constraints to the model parameters. Preliminary results obtained from the first-half sample of seven fields are discussed to demonstrate the significance of the approach.

Our best models suggest that the thick disk component has a local density of [FORMULA] relative to the thin disk, an exponential scale height of [FORMULA] kpc, and mean metallicity [FORMULA] dex with dispersion [FORMULA] dex. However, because the present data cannot exclude the existence of a vertical metallicity gradient [FORMULA] dex/kpc, a sharper picture of the thick disk metallicity structure must await the analysis of the full-survey data in 14 fields.

Key words: Galaxy: abundances – Galaxy: general – Galaxy: stellar content – Galaxy: structure

Send offprint requests to: Roland Buser

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© European Southern Observatory (ESO) 1998

Online publication: March 3, 1998