Related papers: RR Lyrae Variables in NGC 2808
Most Globular Clusters (GC) show chemical inhomogeneities in the composition of their stars, apparently due to a second stellar generation (SG) in which the forming gas is enriched by hot-CNO cycled material processed in stars belonging to…
We use our synthetic Horizontal Branch (HB) procedure to approach the debated problem concerning the adequacy of canonical HB stellar models to account for the observed peaked distribution of RR Lyrae fundamentalised periods in the globular…
Time-series VI CCD photometry of the globular cluster M10 (NGC 6254) is employed to perform a detailed identification, inspection of their light curves, their classification and their cluster membership, of all the known variables reported…
New B, V, I photometry was obtained for a sample of 152 variables (125 RR Lyrae's, 4 anomalous Cepheids, 11 classical Cepheids, 11 eclipsing binaries and a delta Scuti star) in two regions near the bar of the Large Magellanic Cloud (LMC).…
We present Johnson BV, and Kron-Cousins I-band time series data collected over three consecutive nights in a region of 13 arcmin^2 centered on the Galactic Globular Cluster (GGC) NGC3201. The time sampling of current CCD data allowed us to…
Recent pieces of evidence have revealed that most, and possibly all, globular star clusters are composed of groups of stars that formed in multiple episodes with different chemical compositions. In this sense, it has also been argued that…
NGC 6388 and NGC 6441 are anomalies among Galactic globular clusters in that they cannot be readily place into either Oosterhoff group I or Oosterhoff group II despite their significant numbers of RR Lyrae variables. The mean pulsation…
Using an image subtraction method we have searched for variable stars in the globular cluster M14. We confirmed 62 previously known catalogued variables. In addition to the previoulsy known variables we have identified 71 new variables. We…
Purpose: RR Lyrae stars are important distance indicators. They are usually present in globular clusters where they were first discovered. The study of their properties and distribution in our Galaxy and external galaxies constitutes a…
We present near-infrared J,H, and K-band time series observations of the Galactic Globular Cluster (GGC) M92. On the basis of these data, we derived well-sampled light curves for eleven out of the seventeen cluster RR Lyrae variables, and…
We present a search and analysis of variable stars in the recently discovered Crater~II dwarf galaxy. Based on $B$, $V$, $I$ data collected with the Isaac Newton Telescope (FoV$\sim$0.44 square degrees) we detected 37 variable stars, of…
Following a review of our present knowledge about blue subdwarf stars in globular clusters, we present an overview of the results of searches for close binaries among these stars, including results previously published in the literature and…
In this paper, we report the detections of stellar variabilities from the first 2-year observations of sky area of about 1300 square degrees from the Tsinghua University-NAOC Transient Survey (TNTS). A total of 1237 variable stars…
Time-series \emph{VI} CCD photometry of the globular cluster NGC 1261 is employed to study its variable star population. A membership analysis of most variables based on Gaia~DR2 proper motions and colours, was performed prior to the…
We present B and V time series photometry of the M31 satellite galaxy Andromeda XXVII (And XXVII) that we observed with the Large Binocular Cameras of the Large Binocular Telescope. In the field of And XXVII we have discovered a total of 90…
Context. Observational evidence has accumulated in the past years, showing that the Galactic bulge includes two populations, a metal poor and a metal rich one that, in addition to a different metallicity, show different alpha over iron…
We present the first chemical composition study of two unevolved stars in the globular cluster NGC 2808, obtained with the spectrograph X-shooter@VLT. NGC 2808 shows three discrete, well separated main sequences. The most accepted…
We report the discovery of a new subclass of double-mode RR Lyrae stars in the Large and Small Magellanic Clouds. The sample of 22 pulsating stars have been extracted from the latest edition of the OGLE collection of RR Lyrae variables in…
Galactic globular clusters harbour binary systems that are detected as faint X-ray sources. These close binaries are thought to play an important role in the stability of the clusters by liberating energy and delaying the inevitable core…
We present the most extended and homogeneous study carried out so far of the main and early shocks in 1485 RR~Lyrae stars in the Galactic bulge observed by the Optical Gravitational Lensing Experiment (OGLE). We selected non-modulated…