2016/11/30 by S. Tuncel Guctekin, S. Tunçel Güçtekin, S. Bilir +6
Physics and Astronomy · #Absolute magnitude #Astronomy #Astronomy and Astrophysical Research #Astrophysics #Galaxy #Gamma-ray bursts and supernovae #Halo #Metallicity #Parallax #Photometry (optics) #Physics #Stars #Stellar, planetary, and galactic studies #astro-ph.GA
paper · pdf · doi:10.1007/s10509-016-2987-6
Eq. 11 was corrected, results and conclusions are the same. 16 pages, 16 figures and 5 tables, accepted for publication in Astrophysics and Space Science
openalex publication_date 2016/12/21 · arxiv created 2017/09/01 · arxiv updated 2017/09/04 · openalex created_date 2020/08/18 · openalex updated_date 2026/08/05
We used the updated [Fe/H] abundances of 168 F-G type dwarfs and calibrated them to a third order polynomial in terms of reduced ultraviolet excess, δ0.41 defined with ugr data in the SDSS. We estimated the Mg absolute magnitudes for the same stars via the re-reduced Hipparcos parallaxes and calibrated the absolute magnitude offsets, ΔMg, relative to the intrinsic sequence of Hyades to a third order polynomial in terms of δ0.41. The ranges of the calibrations are -2<[Fe/H]≤0.3 dex and 4<Mg≤6 mag. The mean of the residuals and the corresponding standard deviation for the metallicity calibration are 0 and 0.137 mag; while, for the absolute magnitude calibration they are 0 and 0.179 mag, respectively. We applied our procedures to 23,414 dwarf stars in the Galactic field with the Galactic coordinates 85∘≤ b≤90∘, 0∘≤ l≤360∘ and size 78 deg2. We estimated absolute magnitude Mg dependent vertical metallicity gradients as a function of vertical distance Z. The gradients are deep in the range of 0<Z≤5 kpc, while they are very small positive numbers beyond Z=5 kpc. All dwarfs with 5<Mg≤6 mag are thin-disc stars and their distribution shows a mode at (g-r)0≈ 0.38 mag, while the absolute magnitudes 4<Mg≤5 are dominated by thick disc and halo stars, i.e. the apparently bright ones (g0≤18 mag) are thick-disc stars with a mode at (g-r)0∼0.38 mag, while the halo population is significant in the faint stars (g0>18 mag).