Galactic longitude dependent galactic model parameters |
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Institution: | 1. School of Materials Science and Engineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan 250353, PR China;2. Shandong Provincial Key Laboratory of Processing and Testing Technology of Glass and Functional Ceramics, Jinan 250353, PR China |
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Abstract: | We present the Galactic model parameters for thin disc estimated by Sloan Digital Sky Survey (SDSS) data of 14 940 stars with apparent magnitudes 16 < g0 ? 21 in six intermediate latitude fields in the first Galactic quadrant. Star/galaxy separation was performed by using the SDSS photometric pipeline and the isodensity contours in the (g ? r)0 ? (r ? i)0 two colour diagram. The separation of thin disc stars is carried out by the bimodal distribution of stars in the (g ? r)0 histogram, and the absolute magnitudes were evaluated by a procedure presented in the literature (Bilir, S., Karaali, S., Tunçel, S. 2005. AN 326, 321). Exponential density law fits better to the derived density functions for the absolute magnitude intervals 8 < M(g) ? 9 and 11 < M(g) ? 12, whereas sech/sech2 laws are more appropriate for absolute magnitude intervals 9 < M(g) ? 10 and 10 < M(g) ? 11. We showed that the scaleheight and scalelength are Galactic longitude dependent. The average values and ranges of the scaleheight and the scalelength are 〈H〉 = 220 pc (196 ? H ? 234 pc) and 〈H〉 = 1900 pc (1561 ? h ? 2280 pc) respectively. This result would be useful to explain different numerical values claimed for those parameters obtained by different authors for the fields in different directions of the Galaxy. |
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