Related papers: [Fe/H] relations for c-type RR Lyrae Variables bas…
We determine the fundamental stellar parameters of altogether 20 double-mode RR Lyrae (RRd) stars from the Galactic Field and the Large Magellanic Cloud, following our approach employed on the field RRd star BS Comae. The stars were…
The GAIA satellite is likely to observe thousands of RR Lyrae stars within a small spectral window, between 8470A and 8750A, at a resolution of 11,500. In order to derive the metallicity of RR Lyrae stars from Gaia, we have obtained…
We present a theoretical calibration of the RR Lyrae period-luminosity-color and period-color-color relations in the multiband uvby Stroemgren photometric system. Our theoretical work is based on calculations of synthetic horizontal…
By using a large sample of published spectroscopic iron abundances, we point out the importance of gravity correction in deriving more accurate metal abundances for RR Lyrae stars. For the 197 stars with multiple spectra we find overall…
A grid of synthetic horizontal-branch (SHB) models based on HB evolutionary tracks with improved physics has been constructed to reconsider the theoretical calibration of the dependence of M_v(RR) on metallicity in globular clusters, and…
This is the second of a series of papers in which we present a new solution to reconcile the prediction of single stellar population (SSP) models with the observed stellar mass-to-light ($M/L$) ratios of globular clusters (GCs) in M31 and…
We present new empirical infrared Period-Luminosity-Metallicity (PLZ) and Period-Wesenheit-Metallicity (PWZ) relations for RR Lyrae based on the latest Gaia EDR3 parallaxes. The relations are provided in the WISE $W1$ and $W2$ bands, as…
The results of nonlinear, convective models of RR Lyrae pulsators with metal content Z=0.0001 to 0.006 are discussed and several predicted relations connecting pulsational (period and amplitude of pulsation) and evolutionary parameters…
We present HST/ACS observations of RR Lyrae variable stars in six ultra deep fields of the Andromeda galaxy (M31), including parts of the halo, disk, and giant stellar stream. Past work on the RR Lyrae stars in M31 has focused on various…
New CCD photometry of NGC 6366 has lead to the discovery of some variable stars. Two possible Anomalous Cepheids (or Pop II Cepheids), three long period variables, one SX Phe and one eclipsing binary have been found. Also a list of 10…
We present new theoretical period-luminosity-metallicity (PLZ) relations for RR Lyrae stars (RRL) at Spitzer and WISE wavelengths. The PLZ relations were derived using nonlinear, time-dependent convective hydrodynamical models for a broad…
We have undertaken a search for variable stars in the metal-rich globular cluster NGC 6441 using time-series BV photometry. The total number of variables found near NGC 6441 has been increased to ~104, with 48 new variables being found in…
We report the results of CCD V and r photometry of the globular cluster NGC 5466. The difference image analysis technique adopted in this work has resulted in accurate time series photometry even in crowded regions of the cluster enabling…
We compiled a list of about 250 SX Phoenicis stars known in Galactic globular clusters in order to study period-luminosity relation for this type of variable. The absolute magnitudes of these stars are derived using metallicity-luminosity…
Recent work on the luminosities of type II Cepheids (CephIIs) and RR Lyrae variables is reviewed.In the near infrared (JHKs) the CephIIs in globular clusters show a narrow, linear, period-luminosity relation over their whole period range…
We have begun developing a new metallicity calibration for RR Lyrae stars that includes high-temperature phase regions. Our calibration is an updated and expanded version of the Delta-S, equivalent width method, but which is applicable for…
We measure the relationship between stellar mass and stellar metallicity, the stellar mass--metallicity relation (MZR), for 1336 star-forming galaxies at $1.6\le z\le3.0$ (<z>=2.2) using rest-frame far-ultraviolet spectra from the…
We determine a K-band luminosity-metallicity (K-Z) relation for dwarf irregular galaxies, over a large range of magnitudes, -20.5 < M_K < -13.5, using a combination of K photometry from either the 2-micron all sky survey (2MASS) or the…
The luminosities, effective temperatures and metallicities that are derived empirically by Kovacs and Jurcsik from the light curves of a large number of globular cluster and field RRab and RRc stars are compared to theoretical RR Lyrae…
In this article, we present results based on high-density, high-precision Wide-Angle Search for Planets (WASP) light curves supplemented with lower-precision photometry from the All-Sky Automated Survey (ASAS) for 268 RR Lyrae stars (176…