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Galactic longitude dependent galactic model parameters

2006/10/04 by S. Bilir, S. Karaali, S. Ak +3 · 1 citation
Physics and Astronomy · #Absolute magnitude #Astronomy #Astrophysical Phenomena and Observations #Astrophysics #Galaxies: Formation, Evolution, Phenomena #Galaxy #Latitude #Longitude #Magnitude (astronomy) #Physics #Sky #Star count #Stars #Stellar, planetary, and galactic studies #astro-ph

paper · pdf · doi:10.1016/j.newast.2006.10.001

published as New Astron. 12 (2006) 234-245 · 28 pages, including 12 figures and 7 tables, accepted for publication in New Astronomy

arxiv created 2006/10/04 · openalex publication_date 2006/10/25 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05

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<go≤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)o histogram, and the absolute magnitudes were evaluated by a procedure presented in the literature Bilir et al. (2005). 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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