Related papers: The distance to NGC 6397 by M-subdwarf main-sequen…

28 hitherto neglected candidates for the Catalogue of Nearby Stars (CNS) were investigated to verify their classification and to improve their distance estimates. All targets had at least a preliminary status of being nearby dwarf stars…

We report our study of features at the observed red end of the white dwarf cooling sequences for three Galactic globular clusters: NGC\,6397, 47\,Tucanae and M\,4. We use deep colour-magnitude diagrams constructed from archival Hubble Space…

We summarize the x-ray properties of the complete samples of millisecond pulsars (MSPs) detected in our Chandra observations of the globular clusters 47 Tuc and NGC 6397. The 47 Tuc MSPs are predominantly soft sources suggestive of thermal…

We report a peculiar variable blue star in the globular cluster NGC 6397, using Hubble Space Telescope optical imaging. Its position in the colour-magnitude diagrams, and its spectrum, are consistent with this star being a helium core white…

As ancient, gravitationally bound stellar populations, globular clusters are abundant, vibrant laboratories characterized by high frequencies of dynamical interactions coupled to complex stellar evolution. Using surface brightness and…

The dense central region of NGC 6397 contains three classes of stars whose origins are likely related to stellar interactions: blue stragglers, cataclysmic variables, and probable helium white dwarfs. We summarize results concerning CVs and…

We present the results of medium-resolution spectroscopy of 28 globular clusters (GCs) in six nearby galaxies of different luminosities and morphological types, situated in: M33 (15 objects), M31 (3), IC10 (4), UGCA86 (4), HolmbergIX (1),…

Using the Hubble Space Telescope (HST) 37 long-period Cepheid variables have been discovered in the Fornax Cluster spiral galaxy NGC 1365. The resulting V and I period-luminosity relations yield a true distance modulus of 31.35 +/- 0.07…

We investigate the behavior of multiple stellar populations in globular clusters (GCs) using photometric diagrams constructed with Euclid photometry. By employing synthetic spectra and isochrones that incorporate the chemical differences…

We present new period-luminosity and period-luminosity-metallicity relations for Galactic RR Lyrae stars based on a sample of 28 pulsators located at distances up to $1.5$ kpc from the Sun. Near-infrared photometry was obtained at the Cerro…

We present photometric and spectroscopic observations of the optical companion to the millisecond radio pulsar PSR J1740-5340 in the globular cluster NGC 6397. An analysis of the photometric variability in the B, V, and I-bands indicates an…

We present a sample of 135,873 RR Lyrae stars (RRLs) with precise photometric-metallicity and distance estimates from our newly calibrated $P-\phi_{31}-R_{21}-$[Fe/H]/$P-R_{21}-$[Fe/H] and $G$ band absolute magnitude-metallicity relations.…

We combine the globular cluster data for fifteen Brightest Cluster Galaxies and use this material to trace the mass-metallicity relations (MMR) in their globular cluster systems (GCSs). This work extends previous studies which correlate the…

We study the globular cluster system (GCS) of the giant elliptical NGC4374 (M84) in the Virgo cluster using B and R photometry. The colour distribution is bimodal with peaks at B-R=1.11 and B-R=1.36, fitting well to those found in other…

Knowledge of late K and M dwarf metallicities can be used to guide planet searches and constrain planet formation models. However, the determination of metallicities of late-type stars is difficult because visible wavelength spectra of…

We present new BVI photometry of the globular cluster NGC 6981 (M72), based mostly on ground-based CCD archive images. We present a new color-magnitude diagram (CMD) that reaches almost four magnitudes below the turn-off level. We performed…

Hubble Space Telescope imaging for 26 giant early-type galaxies, all drawn from the MAST archive, is used to carry out photometry of their surrounding globular cluster (GC) systems. Most of these targets are Brightest Cluster Galaxies…

We present a photometric study of the globular cluster systems of the Fornax cluster galaxies NGC 1374, NGC 1379, and NGC 1387. The data consists of images from the wide-field MOSAIC Imager of the CTIO 4-m telescope, obtained with…

We present deep near-infrared photometry and spectroscopy of the globular cluster 2MASS-GC03 projected in the Galactic disk using MMIRS on the Clay telescope (Las Campanas Observatory) and VISTA Variables in the Via Lactea survey (VVV)…

We present N-body models to complement deep imaging of the metal-poor core-collapsed cluster NGC6397 obtained with the Hubble Space Telescope. All simulations include stellar and binary evolution in-step with the stellar dynamics and…