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Register a new userThe OGLE Collection of Variable Stars. Over 450 000 Eclipsing and Ellipsoidal Binary Systems Toward the Galactic Bulge
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We present a collection of 450 598 eclipsing and ellipsoidal binary systems detected in the OGLE fields toward the Galactic bulge. The collection consists of binary systems of all types: detached, semi-detached, and contact eclipsing binaries, RS CVn stars, cataclysmic variables, HW Vir binaries, double periodic variables, and even planetary transits. For all stars we provide the I- and V-band time-series photometry obtained during the OGLE-II, OGLE-III, and OGLE-IV surveys. We discuss methods used to identify binary systems in the OGLE data and present several objects of particular interest.
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We present a collection of 10 111 genuine delta Sct-type pulsating variable stars detected in the OGLE-IV Galactic bulge fields. In this sample, 9835 variables are new discoveries. For most of the stars photometric data cover the whole decade 2010-2019. We illustrate a huge variety of light curve shapes of delta Sct variables. Long-term observations have allowed us to spot objects with evident period, amplitude, and mean brightness variations. Our analysis indicates that about 28% of the stars are single-mode pulsators. Fourteen delta Sct stars show additional eclipsing or ellipsoidal binary modulation. We report significant attenuation or even disappearance of the pulsation signal in six sources. The whole set of variables is a mix of objects representing various Milky Ways populations, with the majority of stars from the Galactic bulge. There are also representatives of the Sagittarius Dwarf Spheroidal Galaxy. Some of the newly detected variables could be SX Phe-type stars residing in globular clusters. The collection, including full V- and I-band time-series data, is available to the astronomical community from the OGLE On-line Data Archive.
We present a collection of classical, type II, and anomalous Cepheids detected in the OGLE fields toward the Galactic center. The sample contains 87 classical Cepheids pulsating in one, two or three radial modes, 924 type II Cepheids divided into BL Her, W Vir, peculiar W Vir, and RV Tau stars, and 20 anomalous Cepheids - first such objects found in the Galactic bulge. Additionally, we upgrade the OGLE Collection of RR Lyr stars in the Galactic bulge by adding 828 newly identified variables. For all Cepheids and RR Lyr stars, we publish time-series VI photometry obtained during the OGLE-IV project, from 2010 through 2017. We discuss basic properties of our classical pulsators: their spatial distribution, light curve morphology, period-luminosity relations, and position in the Petersen diagram. We present the most interesting individual objects in our collection: a type II Cepheid with additional eclipsing modulation, W Vir stars with the period doubling effect and the RVb phenomenon, a mode-switching RR Lyr star, and a triple-mode anomalous RRd star.
We present the collection of eclipsing binaries in the Large and Small Magellanic Clouds, based on the OGLE survey. It contains 48605 systems, 40204 belonging to the LMC and 8401 to the SMC. Out of the total number of the presented binaries, 16374 are the new ones. We present the time-series photometry obtained for the selected objects during the fourth phase of the OGLE project. The catalog has been created using a two step machine learning procedure based on the Random Forest algorithm.
We present the discovery and statistical analysis of $12;660$ spotted variable stars toward and inside the Galactic bulge from over two-decade-long Optical Gravitational Lensing Experiment (OGLE) data. We devise a new method of dereddening of individual stars toward the Galactic bulge where strong and highly nonuniform extinction is present. In effect, $11;812$ stars were classified as giants and $848$ as dwarfs. Well defined correlations between the luminosity, variability amplitude and rotation period were found for the giants. Rapidly rotating dwarfs with periods $P leq 2$ d show I-band amplitudes lower than 0.2 mag which is substantially less than the amplitudes of up to 0.8 mag observed in giants and slowly rotating dwarfs. We also notice that amplitudes of stars brighter than $I_0 approx 16$ mag do not exceed 0.3-0.4 mag. We divide the stars into three groups characterized by correlation between light and color variations. The positive correlation is characteristic for stars that are cooler when fainter, which results from the variable coverage of the stellar surface with spots similar to the sunspots. The variability of stars that are cooler when brighter (negative correlation) can be characterized by chemical spots with overabundance of heavy elements inside and variable line-blanketing effect, which is observed in chemically peculiar stars. The null correlation may results from very high level of the magnetic activity with rapidly variable magnetic fields. This division is readily visible on the color-magnitude diagram (CMD), which suggests that it may depend on the radius of the stars. We detect 79 flaring objects and discuss briefly their properties. Among others, we find that relative brightening during flares is correlated with brightness amplitude.
We present the most comprehensive picture ever obtained of the central parts of the Milky Way probed with RR Lyrae variable stars. This is a collection of 38257 RR Lyr stars detected over 182 square degrees monitored photometrically by the Optical Gravitational Lensing Experiment (OGLE) in the most central regions of the Galactic bulge. The sample consists of 16804 variables found and published by the OGLE collaboration in 2011 and 21453 RR Lyr stars newly detected in the photometric databases of the fourth phase of the OGLE survey (OGLE-IV). 93% of the OGLE-IV variables were previously unknown. The total sample consists of 27258 RRab, 10825 RRc, and 174 RRd stars. We provide OGLE-IV I- and V-band light curves of the variables along with their basic parameters. About 300 RR Lyr stars in our collection are plausible members of 15 globular clusters. Among others, we found the first pulsating variables that may belong to the globular cluster Terzan 1 and the first RRd star in the globular cluster M54. Our survey also covers the center and outskirts of the Sagittarius Dwarf Spheroidal Galaxy enabling studies of the spatial distribution of the old stellar population from this galaxy. A group of double-mode RR Lyr stars with period ratios around 0.740 form a stream in the sky that may be a relic of a cluster or a dwarf galaxy tidally disrupted by the Milky Way. Three of our RR Lyr stars experienced a pulsation mode switching from double-mode to single fundamental mode or vice versa. We also present the first known RRd stars with large-amplitude Blazhko effect.
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