Metallicity calibration and photometric parallax estimation: II. SDSS photometry
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- 作者：S. Tunçel Güçtekin ; S. Bilir ; S. Karaali ; O. Plevne…
- 关键词：Galaxy ; disc ; Galaxy ; halo ; Stars ; abundances ; Stars ; distances
- 刊名：Astrophysics and Space Science
- 出版年：2017
- 出版时间：January 2017
- 年：2017
- 卷：362
- 期：1
- 全文大小：
- 刊物类别：Physics and Astronomy
- 刊物主题：Astrophysics and Astroparticles; Astronomy, Observations and Techniques; Cosmology; Space Sciences (including Extraterrestrial Physics, Space Exploration and Astronautics); Astrobiology;
- 出版者：Springer Netherlands
- ISSN：1572-946X
- 卷排序：362
文摘
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, \(\delta_{0.41}\) defined with \(\mathit{ugr}\) data in the SDSS. We estimated the \(M_{g}\) absolute magnitudes for the same stars via the re-reduced Hipparcos parallaxes and calibrated the absolute magnitude offsets, \(\Delta M_{g}\), relative to the intrinsic sequence of Hyades to a third order polynomial in terms of \(\delta_{0.41}\). The ranges of the calibrations are \(-2<\mbox{[Fe/H]}\leq 0.3~\mbox{dex}\) and \(4< M_{g}\leq 6~\mbox{mag}\). 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 \(85^{\circ }\leq b\leq 90^{ \circ }\), \(0^{\circ }\leq l\leq 360^{\circ }\) and size 78 deg2. We estimated absolute magnitude \(M_{g}\) dependent vertical metallicity gradients as a function of vertical distance \(Z\). The gradients are deep in the range of \(0< Z\leq 5~\mbox{kpc}\), while they are very small positive numbers beyond \(Z=5~\mbox{kpc}\). All dwarfs with \(5< M_{g}\leq 6~\mbox{mag}\) are thin-disc stars and their distribution shows a mode at \((g-r)_{0}\approx 0.38~\mbox{mag}\), while the absolute magnitudes \(4< M_{g} \leq 5\) are dominated by thick disc and halo stars, i.e. the apparently bright ones (\(g_{0}\leq 18~\mbox{mag}\)) are thick-disc stars with a mode at \((g-r)_{0}\sim 0.38~\mbox{mag}\), while the halo population is significant in the faint stars (\(g_{0}>18~\mbox{mag}\)).