ﻻ يوجد ملخص باللغة العربية
We present metallicity and photometric parallax calibrations for the F and G type dwarfs with photometric, astrometric and spectroscopic data. The sample consists of 168 dwarf stars covering the colour, iron abundance and absolute magnitude intervals $0.30<(B-V)_0<0.68$ mag, $-2.0<[Fe/H]<0.4$ dex and $3.4<M_V<6.0$ mag, respectively. The means and standard deviations of the metallicity and absolute magnitude residuals are small, i.e. $langleDelta[Fe/H]_{res}rangle=0$ and $sigma=0.134$ dex, and $langleDelta (M_V)_{res}rangle=0$ and $sigma=0.174$ mag, respectively, which indicate accurate metallicity and photometric parallax estimations.
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 $ugr$ data in the SDSS. We estimated the $M_g$ absolute magnitudes for th
We present the results of CCD $UBV$ photometric and spectroscopic observations of the open cluster NGC 225. In order to determine the structural parameters of NGC 225, we calculated the stellar density profile in the clusters field. We estimated the
We present the calibration of the [$alpha/$Fe] element in terms of ultra-violet excess for 465 dwarf stars with spectral type F0-K2. We used a single calibration, fitted to a third degree polynomial with a square of the correlation coefficient 0.74 a
We analysed the open clusters Czernik 2 and NGC 7654 using CCD UBV photometric and Gaia Early Data Release 3 (EDR3) photometric and astrometric data. Structural parameters of the two clusters were derived, including the physical sizes of Czernik 2 be
We present the updated photometric calibration of the twelve optical passbands for the Javalambre Photometric Local Universe Survey (J-PLUS) second data release (DR2), comprising 1088 pointings of two square degrees, and study the systematic impact o