Metallicity calibration and photometric parallax estimation: II. SDSS photometry

Abstract

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, δ 0.41 defined with 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, ∆M g , relative to the intrinsic sequence of Hyades to a third order polynomial in terms of δ 0.41 . 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• and size 78 deg 2 . 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 ≤ 5 kpc, while they are very small positive numbers beyond Z = 5 kpc. All dwarfs with 5 < M g ≤ 6 mag are thin-disc stars and their distribution shows a mode at (g − r) 0 ≈ 0.38 mag, while the absolute magnitudes 4 < M g ≤ 5 are dominated by thick disc and halo stars, i.e. the apparently bright ones (g 0 ≤ 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 (g 0 > 18 mag).

Chemical and Kinematic Properties of the Galactic Disk from the LAMOST and Gaia Sample Stars

“…For the thin disk, most of the researchers found a negative metallicity radial gradient (e.g., Bilir et al 2012;Boeche et al 2013). In the vertical direction, Chen et al (2011), Carrell et al (2012), Li et al (2017), andTunçel et al (2017) found a negative metallicity gradient of the thick disk, while Katz et al (2011) and Li et al (2018) derived a flatter gradient. For the thin disk, a negative metallicity gradient was also found in the vertical direction Duong et al 2018), while Mikolaitis et al (2014 derived a flatter gradient.…”

Photometric calibration of the [ α $\alpha$ /Fe] element: II. Calibration with SDSS photometry

“…The (u−g) 0 and (g −r) 0 colour indices of these stars, taken from Tunçel Güçtekin et al (2017), are used to estimate their U V -excess, δ, which provide [α/Fe] elements via our calibration, i.e. Eq.…”

“…The star sample consists of 23,414 F and G dwarfs taken from Tunçel Güçtekin et al (2017) which were provided by a series of constraints explained in the following. The star sample was defined with Galactic coordinates 85…”

“…A final constraint is related to the absolute magnitudes which were estimated via the procedure in the cited paper. We should emphasize that all these constraints were carried out in Tunçel Güçtekin et al (2017).…”

Bridging the ultraviolet and optical regions: Transformation equations between GALEX and UBV photometric systems

“…Carney 1979;Karaali et al 2003a, b, c;Karataş & Schuster 2006;Karaali et al 2011;Tunçel Güçtekin et al 2016;Çelebi et al 2019). Similar calibrations have been developed for the SDSS photometric system and applied to faint stars (Karaali et al 2005;Bilir et al 2005;Tunçel Güçtekin et al 2017). These calibrations were used to calculate metal abundances (Ak et al 2007;Ivezic et al 2008;Tunçel Güçtekin et al 2019) and estimation of the Galactic model parameters…”