Related papers: RR Lyrae-based calibration of the Globular Cluster…
We have imaged $\sim$ 1 deg$^{2}$ in the V-band in the direction of the Hercules Cluster (Abell 2151). The data are used to compute for the first time the luminosity function (LF) of galaxies in the cluster down to the dwarf regime…
We have obtained new CCD BV photometry of the little-studied southern Galactic globular cluster NGC 5986, including light curves of 5 of its RR Lyrae variables. The cluster's red giant branch bump is detected for the first time at V = 16.47…
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…
Mira variables in globular clusters can provide an accurate and precise absolute calibration of their period-luminosity relations (PLRs) to independently anchor the cosmic distance scale and determine the Hubble constant. We present…
We present an analysis of the globular cluster systems of 28 elliptical galaxies using archival WFPC2 images in the V and I-bands. The V-I color distributions of at least 50% of the galaxies appear to be bimodal {\it at the present level of…
We use theoretical models to establish a tight relationship for the absolute magnitudes of RR Lyrae stars as a function of their periods and Stroemgren pseudo-color c_0 = (u-v)_0 - (v-b)_0. Applying this to RR Lyr, and comparing the result…
We present V and B-band CCD photometry of 35 RR Lyr stars in the southern hemisphere globular cluster NGC 6362. Fourier decomposition of the light curves was used to estimate the basic properties of these variables. From the analysis of the…
We have investigated the results for [Fe/H] and distance for a group of 24 globular clusters in the Galactic bulge, employing recent calibrations of RR Lyrae light curves Fourier decomposition and period-absolute magnitude-metallicity (PMZ)…
Recent work has established large samples of astrometrically confirmed RR Lyrae and type-II Cepheid members of Galactic globular clusters (GCs). Any given GC can contain multiple such stars at once, notably RR Lyrae stars pulsating in the…
We review selected measurements of the galaxy luminosity function including the global field, the local group, the local sphere, nearby clusters (Virgo, Coma and Fornax) and clusters in general. We conclude that the overall cluster…
Globular clusters are both primary fossils of galactic evolution and formation and are ideal laboratories for constraining the evolution of low-mass and metal-poor stars. RR Lyrae and type II Cepheid variables are low-mass, radially…
We present new spatial models and distance estimates for globular clusters (GC) and dwarf spheroidals (dSphs) orbiting our Galaxy based on RR Lyrae (RRab) stars in the Pan-STARRS1 (PS1) 3$\pi$ survey. Using the PS1 sample of RRab stars from…
Infrared JKs-band photometry of the Galactic globular clusters M15 and, for the first time, M56 is presented. We estimated the reddening (E(B-V)=0.18+/-0.08 mag) and distance modulus ((m-M)_V=15.43+/-0.30 mag) towards the poorly studied…
I explore the consequences of making the RR Lyrae and clump giant distance scales consistent in the solar neighborhood, Galactic bulge and Large Magellanic Cloud (LMC). I employ two major assumptions: 1) that the absolute magnitude -…
We briefly describe a method of obtaining relative intrinsic stellar parameters, such as absolute magnitudes and colors from the light curves of fundamental mode RR Lyrae (RRab) stars. Absolute stellar parameters of double-mode variables…
We have used deep HST/WFPC2 images in V (F606W) and I (F814W) to measure the luminosity distribution of the globular clusters in NGC 4874, the central cD galaxy of the Coma cluster. We find the ``turnover'' point of the globular cluster…
We have determined the absolute magnitude at maximum light of SN 1992A by using the turn-over magnitude of the Globular Cluster Luminosity Function of its parent galaxy, NGC 1380. A recalibration of the peak of the turn-over magnitude of…
We present the radial velocities, metallicities and the K-band magnitudes of 74 RR Lyrae stars in the inner regions of the LMC. The intermediate resolution spectra and infrared images were obtained with FORS1 at the ESO VLT and with the…
New photometry of RRab and RRc stars in Omega Cen is used to calibrate their absolute magnitudes M_V as a function of: a) metallicity; and b) the Fourier parameters of light curves in the V band. The zero point of both calibrations relies…
RR Lyrae stars are one of the primary distance indicators for old stellar populations such as globular clusters, dwarf galaxies and galaxies. Typically, fundamental-mode RR Lyr stars are used for distance measurements, and their accuracy is…