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Comprehensive Analysis of RGU Photometry in the Direction to M5

Published online by Cambridge University Press:  05 March 2013

S. Karaali*
Affiliation:
Istanbul University, Department of Astronomy and Space Sciences, 34452 University-Istanbul, Turkey
S. Bilir
Affiliation:
Istanbul University, Department of Astronomy and Space Sciences, 34452 University-Istanbul, Turkey
R. Buser
Affiliation:
Astronomisches Institut der Universität Basel, 4102 Binningen, Switzerland
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Abstract

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The RGU-photographic investigation of an intermediate latitude field in the direction to the Galactic centre is presented. 164 extra-galactic objects, identified by comparison of Minnesota and Basel charts, are excluded from the program. Also, a region with size 0.104 square-degrees, contaminated by cluster (M5) stars and affected by background light of the bright star HD 136202 is omitted. Contrary to previous investigations, a reddening of E(BV) = 0.046, corresponding to E(GR) = 0.07 mag is adopted. The separation of dwarfs and evolved stars is carried out by an empirical method, already applied in some of our works. A new calibration for the metallicity determination is used for dwarfs, while the absolute magnitude determination for stars of all categories is performed using the procedures given in the literature. There is good agreement between the observed logarithmic space density histograms and the galactic model gradients. Also, the local luminosity function agrees with Gliese's (1969) and Hipparcos (Jahreiss & Wielen 1997) luminosity functions, for stars with 2 < M(G) ≤ 8 mag. For giants, we obtained two different local space densities from comparison with two Galactic models, i.e. D*(0) = 6.63, close to that of Gliese (1969), and D*(0) = 6.79. A metallicity gradient, d[Fe/H]/dz = –0.20 dex kpc–1, is detected for dwarfs (only) with absolute magnitudes 4 < M(G) ≤ 6, corresponding to a spectral type interval F5–K0.

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Type
Research Article
Copyright
Copyright © Astronomical Society of Australia 2004