We collect 24 times of light maxima data from sources in the literature, unpublished data and open databases, and investigate the variations of the observed and calculated (O-C) values for light maxima of V1719 Cyg. We found no evidence of the variations in the (O-C) values. We estimate the effective temperature and surface gravity using both the Kurucz and MARCS/SSG grids for different metallicity values [A/H]=0.0 and +0.5 for V1719 Cyg. It is confirmed that the temperature is almost the same, but, in the case of surface gravity, the MARCS/SSG grid gives the value closest to that obtained from the period-gravity relation derived by using the pulsation-evolution theory. We obtain two spectra of V1719 Cyg from spectroscopic observation which permitted us to find the effective temperature and the surface gravity of the star directly. We estimate the metallicity and it is found that the abundance of iron is equal to the solar value.

We derive a new relationship between the giant branch slope as measured in the color-magnitude diagram (K, J - K) and [Fe/H] metallicity for old open clusters. Previously such relationships have been derived for globular clusters, while similar tendency has been expected for open clusters. New derived correlation, [Fe/H]=-17.2(±0.23)GB slope - 1.95(±0.02), is based on a collection of data for 10 old open clusters. Most clusters behave as expected from the theoretical predictions.

In order to determine the metallicity of a globuar cluster, M3,by using the spectral indices, a kind of index grid has been establshed by stars in globular clusters, M3, M15, M71 and old open cluster, NGC 188. The indices were measured from the medium resolution spectra of about 2 Å. The summed indices were used to determine metallicity in order to increase signals. It is found that the core depth index is measured more accurately and leads result more accurate than the pseudo-equivalent width index. This method can be further improved by including many more calibration globular clusters of various metallicity to make finer grids. By this method, the metallicity of M3 is determined as [Fe/H] = -1.46±0.15.

The ages of field stars given in the catalogue of Cayrel de Strobel et al. (1985) are derived by the five different methods with combination of theoretical isochrones. By using these ages and metal abundances homogenized by Lee and Choe (1988), the age-metallicity relations are obtained. For disk stars of [Fe/H] > -0.9, the present age-metallicity relations are nearly consistent with those given by Twarog (1980) and Carlberg et al. (1985).

From the uvby, H β photometry of intermediate population II F-stars in the catalogue of Olsen (1983), we derived age-metallicity relations for these stars, using Hejlesen's (1980) isochrone. The derived age-metallicity relations well coincide with the theoretical predictions by the unclosed two-zone model of Lee and Ann (1981). There are few extremely metal poor F-stars in the vicinity of the Sun, and it is very likely that the initial rapid metal enrichment in the galactic disk might have been processed through the fast collapse of the disk at the very early epoch.

For F,G,K stars, their photometric data and metallicity, [Fe/H] are collected and their correlations between δ δ (U-B) and [Fe/H] for each spectral group are examined, using a reference sequence which is defined by the stars in Woolley's catalogue and other reference sequences. Detailed examination shows that the reference sequence by Woolley's catalogue appears to be properly defined for the calculation of δ δ (U-B) of population I stars in the solar neighborhood. It is suggested that accuracies of metallicities derived from δ δ (U-B) can be improved if we derive the correlations between [Fe/H] and δ δ (U-B) from the stars in each spectral group.

For ∼ 240 nearby stars their age and mass were determined and kinematic parameters determined for 362 stars, applying Woolley's three-dimensional potential. Metallicity and kinematic parameters of these stars were correlated with their age, suggesting the slow collapse ( t ≳ a few billion years) of the Galaxy and the initial rapid enrichment in metal abundance ( Δ Z ≈ 1 / 3 Z 1 (present) for ∼ 4 × 10 8 yrs). The late slow enrichment rate is given by d ( Z / Z ⊙ ) / d t = 5.9 ∼ 7.0 ± 3.4 per Gyr.

We present a spectroscopic study of 343 blue compact galaxies (BCGs) at 0.20 < z < 0.35 from the Sloan Digital Sky Survey (SDSS) DR7 data. We derive gas phase oxygen abundance using the empirical and direct method. Stellar masses of galaxies are derived from the STARLIGHT code. We also derive star formation rates of galaxies based on Hα emission line from the SDSS as well as far-ultraviolet (FUV) flux from the Galaxy Evolution Explorer GR6 data. Evolution of the luminosity-metallicity and mass-metallicity (M-Z) relations with redshift is observed. At a given luminosity and mass, galaxies at higher redshifts appear to be biased to low metallicities relative to the lower redshift counterparts. Furthermore, low mass galaxies show higher specific star formation rates (SSFRs) than more massive ones and galaxies at higher redshifts are biased to higher SSFRs compared to the lower redshift sample. By visual inspection of the SDSS images, we classify galaxy morphology into disturbed or undisturbed. In the M-Z relation, we find a hint that morphologically disturbed BCGs appear to exhibit low metallicities and high SSFRs compared to undisturbed counterparts. We suggest that our results support downsizing galaxy formation scenario and star formation histories of BCGs are closely related with their morphologies.