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Results for "I. Soszyński"

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Search for binary central stars of the SMC PNeDec 20 2013The Optical Gravitational Lensing Experiment (OGLE), originally designed to search for microlensing events, provides a rich and uniform data set suitable for studying the variability of certain types of objects. We used the OGLE data to study the photometry ... More
Final Release of the OGLE Collection of Cepheids and RR Lyrae Stars in the Magellanic System. The Outer RegionsJul 03 2019We present the final release of the OGLE collection of classical pulsators (Cepheids and RR Lyr stars) in the Large and Small Magellanic Clouds. The sky coverage has been increased from 670 to 765 square degrees compared to the previous edition of the ... More
On the long cycle variability of the Algol OGLE-LMC-DPV-065 and its stellar, orbital and disk parametersMay 10 2019OGLE-LMC-DPV-065 is an interacting binary whose double-hump long photometric cycle remains hitherto unexplained. We analyze photometric time series available in archive datasets spanning 124 years and present the analysis of new high-resolution spectra. ... More
Type II Cepheids Pulsating in the First Overtone from the OGLE SurveyFeb 06 2019We report the discovery of the first type II Cepheids (BL Herculis stars) pulsating solely in the first overtone. We found two such objects among tens of millions of stars regularly observed by the OGLE survey in the Large Magellanic Cloud. Our classification ... More
Spitzer as Microlens Parallax Satellite: Mass Measurement for the OGLE-2014-BLG-0124L Planet and its Host StarOct 15 2014We combine Spitzer and ground-based observations to measure the microlens parallax vector ${\mathbf \pi}_{\rm E}$, and so the mass and distance of OGLE-2014-BLG-0124L, making it the first microlensing planetary system with a space-based parallax measurement. ... More
An X-Shooter view of the symbiotic star [JD2002] 11Aug 01 2015We aimed to verify the nature and derive the basic parameters of the symbiotic star candidate [JD2002] 11. For this purpose, we obtained and analysed an X-Shooter spectrum of [JD2002] 11. We also used optical and infrared photometry available for the ... More
Long Secondary Periods in Variable Red GiantsJul 17 2009We present a study of a sample of LMC red giants exhibiting Long Secondary Periods (LSPs). We use radial velocities obtained from VLT spectral observations and MACHO and OGLE light curves to examine properties of the stars and to evaluate models for the ... More
The SMC B-type supergiant AzV322: a g-mode pulsator with a circumstellar discOct 06 2017We present a photometric and spectroscopic study of AzV322, an emission line object located in the Small Magellanic Cloud previously classified between O9 and B0. We analyze 17.5 years of $I$ and $V$ band OGLE-II, III and IV light curves and find four ... More
The Araucaria Project. Binary Classical Cepheids in the LMCJul 07 2014The status of our work on binary classical cepheid systems in the Large Magellanic Cloud is presented. We report on results from our follow up of two eclipsing binary cepheids OGLE-LMC-CEP-0227 and OGLE-LMC-CEP-1812. Here we presented for the first time ... More
Photometry of two unusual A supergiant systems in the Small Magellanic CloudApr 15 2010We present multiwavelength broadband photometry and V, I time resolved photometry for two variable bright stars in the SMC, OGLE004336.91-732637.7 (SMC-SC3) and OGLE004633.76-731204.3 (SMC-SC4). The light curves span 12 years and show long-term periodicities ... More
Chemical evolution of the Galactic bulge as traced by microlensed dwarf and subgiant stars. VI. Age and abundance structure of the stellar populations in the central sub-kpc of the Milky WayFeb 09 2017Jul 10 2017We present a detailed elemental abundance study of 90 F and G dwarf, turn-off and subgiant stars in the Galactic bulge. Based on high-resolution spectra acquired during gravitational microlensing events, stellar ages and abundances for 11 elements (Na, ... More
A Super-Jupiter Microlens Planet Characterized by High-Cadence KMTNet Microlensing Survey Observations of OGLE-2015-BLG-0954Feb 29 2016Jun 23 2016We report the characterization of a massive (m_p=3.9 +- 1.4 M_jup) microlensing planet (OGLE-2015-BLG-0954Lb) orbiting an M dwarf host (M=0.33 +- 0.12 M_sun) at a distance toward the Galactic bulge of 0.6 (+0.4,-0.2) kpc, which is extremely nearby by ... More
OGLE-2017-BLG-0537: Microlensing Event with a Resolvable Lens in $\lesssim 5$ years from High-resolution Follow-up ObservationsJun 21 2018We present the analysis of the binary-lens microlensing event OGLE-2017-BLG-0537. The light curve of the event exhibits two strong caustic-crossing spikes among which the second caustic crossing was resolved by high-cadence surveys. It is found that the ... More
The Optical Gravitational Lensing Experiment. The OGLE-III Catalog of Variable Stars. X. Enigmatic Class of Double Periodic Variables in the Large Magellanic CloudSep 27 2010Oct 26 2010The tenth part of the OGLE-III Catalog of Variable Stars contains 125 Double Periodic Variables (DPVs) from the Large Magellanic Cloud. DPVs are semi-detached binaries which show additional variability with a period around 33 times longer than the orbital ... More
The Optical Gravitational Lensing Experiment. OGLE-III Photometric Maps of the Galactic Bulge FieldsJul 20 2011We present OGLE-III Photometric Maps of the Galactic bulge fields observed during the third phase of the OGLE project. This paper describes the last, concluding set of maps based on OGLE-III data. The maps contain precise, calibrated VI photometry of ... More
The Optical Gravitational Lensing Experiment. The OGLE-III Catalog of Variable Stars. XII. Eclipsing Binary Stars in the Large Magellanic CloudAug 01 2011We present catalog of 26 121 visually inspected eclipsing binary stars identified in the Large Magellanic Cloud during the third phase of the Optical Gravitational Lensing Experiment. The sample is limited to the out-of-eclipse brightness I < 20 mag. ... More
The Optical Gravitational Lensing Experiment. The OGLE-III Catalog of Variable Stars. VI. Delta Scuti Stars in the Large Magellanic CloudApr 06 2010The sixth part of the OGLE-III catalog of Variable Stars presents \delta Sct pulsators in the Large Magellanic Cloud. Altogether 2786 variable stars were found and amongst them 92 are multi-mode objects, including 67 stars pulsating in the fundamental ... More
The Optical Gravitational Lensing Experiment. OGLE-III Photometric Maps of the Galactic Disk FieldsJan 10 2011We present OGLE-III Photometric Maps of the Galactic disk fields observed during the OGLE-III campaigns for low luminosity transiting objects that led to the discovery of the first transiting exoplanets. The maps contain precise, calibrated VI photometry ... More
The Optical Gravitational Lensing Experiment. The Catalog of Stellar Proper Motions toward the Magellanic CloudsMar 12 2012Apr 25 2012We present a catalog of over 6.2 million stars with measured proper motions. All these stars are observed in the direction of the Magellanic Clouds within the brightness range 12 < I < 19 mag. Based on these proper motions about 440 000 Galactic foreground ... More
Using Orbital Effects to Break the Close/wide Degeneracy in Binary-lens Microlensing EventsOct 16 2012Dec 14 2012Microlensing can provide an important tool to study binaries, especially those composed of faint or dark objects. However, accurate analysis of binary-lens light curves is often hampered by the well-known degeneracy between close (s<1) and wide (s>1) ... More
The Araucaria Project: The First-Overtone Classical Cepheid in the Eclipsing System OGLE-LMC-CEP-2532Apr 17 2015We present here the first spectroscopic and photometric analysis of the double-lined eclipsing binary containing the classical, first-overtone Cepheid OGLE-LMC-CEP-2532 (MACHO 81.8997.87). The system has an orbital period of 800 days and the Cepheid is ... More
The OGLE Collection of Variable Stars. Type II Cepheids in the Magellanic SystemJun 29 2018We present a nearly complete collection of type II Cepheids in the Magellanic System. The sample consists of 338 objects: 285 and 53 variables in the Large and Small Magellanic Clouds, respectively. Based on the pulsation periods and light-curve morphology, ... More
OGLE-2015-BLG-1482L: the first isolated low-mass microlens in the Galactic bulgeMar 17 2017Mar 21 2017We analyze the single microlensing event OGLE-2015-BLG-1482 simultaneously observed from two ground-based surveys and from \textit{Spitzer}. The \textit{Spitzer} data exhibit finite-source effects due to the passage of the lens close to or directly over ... More
MOA-2011-BLG-322Lb: a "second generation survey" microlensing planetSep 30 2013Dec 26 2013Global "second-generation" microlensing surveys aim to discover and characterize extrasolar planets and their frequency, by means of round-the-clock high-cadence monitoring of a large area of the Galactic bulge, in a controlled experiment. We report the ... More
OGLE-2012-BLG-0724Lb: A Saturn-mass Planet around an M-dwarfApr 19 2016We report the discovery of a planet by the microlensing method, OGLE-2012-BLG-0724Lb. Although the duration of the planetary signal for this event was one of the shortest seen for a planetary event, the anomaly was well covered thanks to high cadence ... More
The second multiple-planet system discovered by microlensing: OGLE-2012-BLG-0026Lb, c, a pair of jovian planets beyond the snow lineOct 16 2012Dec 04 2012We report the discovery of a planetary system from observation of the high-magnification microlensing event OGLE-2012-BLG-0026. The lensing light curve exhibits a complex central perturbation with multiple features. We find that the perturbation was produced ... More
Gaia and Variable StarsNov 24 2016We present a comparison of the Gaia DR1 samples of pulsating variable stars - Cepheids and RR Lyrae type - with the OGLE Collection of Variable Stars aiming at the characterization of the Gaia mission performance in the stellar variability domain. Out ... More
OGLE-ing the Magellanic System: Photometric Metallicity from Fundamental Mode RR Lyrae StarsJul 29 2016Nov 08 2016In an era of extensive photometric observations, the catalogs of RR Lyr type variable stars number tens of thousands of objects. The relation between the iron abundance [Fe/H] and the Fourier parameters of the stars light curve allows us to investigate ... More
OGLE-2013-BLG-0578L: Microlensing Binary Composed of A Brown Dwarf And An M DwarfMar 11 2015Determining physical parameters of binary microlenses is hampered by the lack of information about the angular Einstein radius due to the difficulty of resolving caustic crossings. In this paper, we present the analysis of the binary microlensing event ... More
Blazhko-type modulation in the double-mode RR Lyrae stars of the OGLE Galactic bulge collectionNov 10 2014Dec 16 2014We present the analysis of Blazhko-type modulation in double-mode RR Lyrae (RRd) stars found in the OGLE photometry of the Galactic bulge. Modulation is detected in 15 stars. Most of them have non-typical period ratio of the radial modes. In the Petersen ... More
V1309 Scorpii: merger of a contact binaryDec 01 2010Feb 10 2011Stellar mergers are expected to take place in numerous circumstences in the evolution of stellar systems. In particular, they are considered as a plausible origin of stellar eruptions of the V838 Mon type. V1309 Sco is the most recent eruption of this ... More
OGLE Collection of Galactic CepheidsOct 22 2018We present here a new major part of the OGLE Collection of Variable Stars - OGLE Collection of Galactic Cepheids. The new dataset was extracted from the Galaxy Variability Survey images - a dedicated large-scale survey of the Galactic disk and outer bulge ... More
Eclipsing Binaries with Classical Cepheid Component in the Magellanic SystemJan 07 2016We present a census of eclipsing binary systems with classical Cepheid as a component. All such systems known were found in the OGLE collection of classical Cepheids in the Magellanic System. We extend the list of potential candidates adding four new ... More
Three-Dimensional Distributions of Type II Cepheids and Anomalous Cepheids in the Magellanic Clouds. Do these Stars Belong to the Old, Young or Intermediate-Age Population?Sep 05 2018Oct 24 2018The nature of type II Cepheids and anomalous Cepheids is still not well known and their evolutionary channels leave many unanswered questions. We use complete collection of classical pulsating stars in the Magellanic Clouds discovered by the OGLE project, ... More
Concluding Henrietta Leavitt's Work on Classical Cepheids in the Magellanic System and Other Updates of the OGLE Collection of Variable StarsJun 28 2017Jul 03 2017More than a century ago, Henrietta Leavitt discovered the first Cepheids in the Magellanic Clouds together with the famous period-luminosity relationship revealed by these stars, which soon after revolutionized our view of the Universe. Over the years, ... More
The Dusty Aftermath of the V1309 Sco Binary MergerJan 08 2013Jan 10 2013We present mid-IR photometry and spectra of the merged binary V1309 Sco taken between 18 and 23 months after outburst. Strong mid-IR emission and a solid state absorption feature indicate the presence of a significant amount of dust in the circumstellar ... More
The OGLE Collection of Variable Stars. Eclipsing Binaries in the Magellanic SystemDec 19 2016We 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 ... More
OGLE-2014-BLG-0257L: A Microlensing Brown Dwarf Orbiting a Low-mass M DwarfMar 15 2016In this paper, we report the discovery of a binary composed of a brown dwarf and a low-mass M dwarf from the observation of the microlensing event OGLE-2014-BLG-0257. Resolution of the very short-lasting caustic crossing combined with the detection of ... More
The VLT-FLAMES Tarantula Survey V. The peculiar B[e]-like supergiant, VFTS698, in 30 DoradusJan 30 2012Apr 20 2012We present an analysis of a peculiar supergiant B-type star (VFTS698/Melnick 2/Parker 1797) in the 30 Doradus region of the Large Magellanic Cloud which exhibits characteristics similar to the broad class of B[e] stars. We analyse optical spectra from ... More
The Optical Gravitational Lensing Experiment. Dwarf Novae in the OGLE Data. I. Three New Dwarf Novae: One in the Period Gap and Two Longer Period ObjectsJul 12 2011We report serendipitous discovery of three new dwarf novae which eruptions in 2010 were observed by the ongoing microlensing survey OGLE-IV. All three objects are located in the Galactic bulge fields observed with the highest cadence of 20 minutes. In ... More
New R Coronae Borealis stars discovered in OGLE-III Galactic Bulge fields from their mid- and near- infrared propertiesJul 06 2010Mar 16 2011An R Coronae Borealis (RCB) star is a rare type of supergiant star that is increasingly thought to be the evolved merger product of two white dwarfs. Recently, many of them have been found distributed in a thin disk structure embedded inside the Galactic ... More
Mass and p-factor of the type II Cepheid OGLE-LMC-T2CEP-098 in a binary systemApr 25 2017We present the results of a study of the type II Cepheid ($P_{puls} = 4.974 d$) in the eclipsing binary system OGLE-LMC-T2CEP-098 ($P_{orb} = 397.2 d$). The Cepheid belongs to the peculiar W Vir group, for which the evolutionary status is virtually unknown. ... More
The panchromatic view of the Magellanic Clouds from Classical Cepheids. I. Distance, Reddening and Geometry of the Large Magellanic Cloud diskSep 12 2016Sep 13 2016We present a detailed investigation of the Large Magellanic Cloud (LMC) disk using classical Cepheids. Our analysis is based on optical (I,V; OGLE-IV), near-infrared (NIR: J,H,Ks) and mid-infrared (MIR: w1; WISE) mean magnitudes. By adopting new templates ... More
OGLE-ing the Magellanic System: Photometric Metallicity from Fundamental Mode RR Lyrae StarsJul 29 2016In an era of extensive photometric observations, the catalogs of RR Lyrae type variable stars number tens of thousands of objects. The relation between the iron abundance [Fe/H] and the Fourier parameters of the stars light curve allows us to investigate ... More
Analysis of photometric uncertainties in the OGLE-IV Galactic Bulge microlensing survey dataApr 07 2016We present a statistical assessment of both, observed and reported, photometric uncertainties in the OGLE-IV Galactic bulge microlensing survey data. This dataset is widely used for the detection of variable stars, transient objects, discovery of microlensing ... More
A New 3-D Picture of the Milky Way with Classical CepheidsJun 27 2018Aug 16 2018The global view of the Milky Way as a barred spiral galaxy was inferred from various tracers, e.g., star counts or radio maps of Galactic gas, as well as from our extrapolation of structures seen in other galaxies. However, distances to these tracers ... More
The OGLE Collection of Variable Stars. Over 450 000 Eclipsing and Ellipsoidal Binary Systems Toward the Galactic BulgeJan 11 2017We 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 ... More
The OGLE Collection of Variable Stars. Over 45 000 RR Lyrae Stars in the Magellanic SystemJun 08 2016Jul 14 2016We present the largest collection of RR Lyrae stars in the Magellanic System and in its foreground. The sample consists of 45 451 RR Lyr stars, of which 39 082 were detected toward the Large Magellanic Cloud and 6369 toward the Small Magellanic Cloud. ... More
The Variable Stars from the OGLE-III Shallow Survey in the Large Magellanic CloudJun 20 2013We describe variable stars found in the data collected during the OGLE-III Shallow Survey covering the I-band magnitude range from 9.7 mag to 14.5 mag. The main result is the extension of period--luminosity relations for Cepheids up to 134 days. We also ... More
Extracting Microlensing Signals from K2 Campaign 9Apr 27 2017Aug 20 2017The reduction of the \emph{K2}'s Campaign 9 (K2C9) microlensing data is challenging mostly because of the very crowded field and the unstable pointing of the spacecraft. In this work, we present the first method that can extract microlensing signals from ... More
Gravitational Binary-lens Events with Prominent Effects of Lens Orbital MotionJun 17 2013Gravitational microlensing events produced by lenses composed of binary masses are important because they provide a major channel to determine physical parameters of lenses. In this work, we analyze the light curves of two binary-lens events OGLE-2006-BLG-277 ... More
OGLE-2012-BLG-0455/MOA-2012-BLG-206: Microlensing event with ambiguity in planetary interpretations caused by incomplete coverage of planetary signalMar 07 2014Apr 10 2014Characterizing a microlensing planet is done from modeling an observed lensing light curve. In this process, it is often confronted that solutions of different lensing parameters result in similar light curves, causing difficulties in uniquely interpreting ... More
Physical parameters and the projection factor of the classical Cepheid in the binary system OGLE-LMC-CEP-0227Aug 23 2013A novel method of analysis of double-lined eclipsing binaries containing a radially pulsating star is presented. The combined pulsating-eclipsing light curve is built up from a purely eclipsing light curve grid created using an existing modeling tool. ... More
Accurate stellar parameters and distance to two evolved eclipsing binary systems, OGLE-BLG-ECL-123903 and OGLE-BLG-ECL-296596, towards the Galactic bulgeApr 09 2019Aim: Our aim is to obtain high-accuracy measurements of the physical and orbital parameters of two evolved eclipsing binary systems, and to use these measurements to study their evolutionary status. We also aim to derive distances to the systems by using ... More
OGLE Collection of Star Clusters. New Objects in the Magellanic Bridge and the Outskirts of the Small Magellanic CloudJan 17 2018The Magellanic System (MS) encompasses the nearest neighbors of the Milky Way, the Large (LMC) and Small (SMC) Magellanic Clouds, and the Magellanic Bridge (MBR). This system contains a diverse sample of star clusters. Their parameters, such as the spatial ... More
The OGLE Collection of Variable Stars. Classical, Type II, and Anomalous Cepheids toward the Galactic CenterDec 04 2017Jan 23 2018We 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, ... More
OGLE-ing the Magellanic System: Stellar populations in the Magellanic BridgeMay 28 2014Sep 30 2014We report the discovery of a young stellar bridge, that forms a continuous connection between the Magellanic Clouds. This finding is based on number density maps for stellar populations found in data gathered by OGLE-IV, that fully cover over 270 deg^2 ... More
OGLE-ing the Magellanic System: RR Lyrae Stars in the BridgeApr 16 2019We use the extended and updated OGLE Collection of Variable Stars to thoroughly analyze distribution of RR Lyrae stars in the Magellanic Bridge. We use photometric metallicities to derive absolute Wesenheit magnitude and then individual distance of each ... More
Variable classification in the LSST era: Exploring a model for quasi-periodic light curvesDec 14 2016LSST is expected to yield ~10^7 light curves over the course of its mission, which will require a concerted effort in automated classification. Stochastic processes provide one means of quantitatively describing variability with the potential advantage ... More
OGLE-ing the Magellanic System: Three-Dimensional Structure of the Clouds and the Bridge Using RR Lyrae StarsNov 08 2016We present a three-dimensional analysis of a sample of 22 859 type $ab$ RR Lyrae stars in the Magellanic System from the OGLE-IV Collection of RR Lyrae stars. The distance to each object was calculated based on its photometric metallicity and a theoretical ... More
Anomalous Double-Mode RR Lyrae Stars in the Magellanic CloudsAug 01 2016We 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 the Magellanic ... More
OGLE-BLG182.1.162852: An Eclipsing Binary with a Circumstellar DiskOct 09 2014We present the discovery of a plausible disk-eclipse system OGLE-BLG182.1.162852. The OGLE light curve for OGLE-BLG182.1.162852 shows three episodes of dimming by $I \simeq 2 - 3$ magnitudes, separated by 1277 days. The shape of the light curve during ... More
Intriguing triple-mode RR Lyrae star with period doublingNov 11 2014Dec 22 2014We report the discovery of an intriguing triple-mode RR Lyrae star found in the OGLE Galactic bulge collection, OGLE-BLG-RRLYR-24137. In the OGLE catalog the star was identified as RRd star - double-mode pulsator, pulsating simultaneously in the fundamental ... More
A Gravitationally Lensed Quasar Discovered in OGLEJan 25 2018We report the discovery of a new gravitationally lensed quasar (double) from the Optical Gravitational Lensing Experiment (OGLE) identified inside the $\sim$670 sq. deg area encompassing the Magellanic Clouds. The source was selected as one of $\sim$60 ... More
$12\;660$ spotted stars toward the OGLE Galactic bulge fieldsMar 13 2019We 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 ... More
OGLE-ing the Magellanic System: Three-Dimensional Structure of the Clouds and the Bridge Using RR Lyrae StarsNov 08 2016Jul 10 2017We present a three-dimensional analysis of a sample of 22 859 type $ab$ RR Lyrae stars in the Magellanic System from the OGLE-IV Collection of RR Lyrae stars. The distance to each object was calculated based on its photometric metallicity and a theoretical ... More
$12\;660$ spotted stars toward the OGLE Galactic bulge fieldsMar 13 2019Jun 19 2019We 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 ... More
First Space-based Microlens Parallax Measurement of an Isolated Star: Spitzer Observations of OGLE-2014-BLG-0939Oct 20 2014Nov 23 2014We present the first space-based microlens parallax measurement of an isolated star. From the striking differences in the lightcurve as seen from Earth and from Spitzer (~1 AU to the West), we infer a projected velocity v_helio,projected ~ 250 km/s, which ... More
OGLE-ing the Magellanic System: Cepheids in the BridgeApr 17 2019We present a detailed analysis of Magellanic Bridge Cepheid sample constructed using the OGLE Collection of Variable Stars. Our updated Bridge sample contains 10 classical and 13 anomalous Cepheids. We calculate their individual distances using optical ... More
OGLE Collection of Star Clusters. New Objects in the Outskirts of the Large Magellanic CloudSep 26 2016The Magellanic System (MS), consisting of the Large Magellanic Cloud (LMC), the Small Magellanic Cloud (SMC) and the Magellanic Bridge (MBR), contains diverse sample of star clusters. Their spatial distribution, ages and chemical abundances may provide ... More
OGLE-ing the Magellanic System: Three-Dimensional Structure of the Clouds and the Bridge Using Classical CepheidsFeb 29 2016Jul 12 2016We analyzed a sample of 9418 fundamental-mode and first-overtone Classical Cepheids from the OGLE-IV Collection of Classical Cepheids. The distance to each Cepheid was calculated using the period-luminosity relation for the Wesenheit magnitude, fitted ... More
Microlensing Discovery of a Tight, Low Mass-ratio Planetary-mass Object around an Old, Field Brown DwarfJul 24 2013Jul 26 2013Observations of accretion disks around young brown dwarfs have led to the speculation that they may form planetary systems similar to normal stars. While there have been several detections of planetary-mass objects around brown dwarfs (2MASS 1207-3932 ... More
Candidate Gravitational Microlensing Events for Future Direct Lens ImagingMar 12 2014The mass of the lenses giving rise to Galactic microlensing events can be constrained by measuring the relative lens-source proper motion and lens flux. The flux of the lens can be separated from that of the source, companions to the source, and unrelated ... More
An analysis of binary microlensing event OGLE-2015-BLG-0060Jun 06 2019We present the analysis of stellar binary microlensing event OGLE-2015-BLG-0060 based on observations obtained from 13 different telescopes. Intensive coverage of the anomalous parts of the light curve was achieved by automated follow-up observations ... More
OGLE16aaa - a Signature of a Hungry Super Massive Black HoleJun 09 2016We present the discovery and first three months of follow-up observations of a currently on-going unusual transient detected by the OGLE-IV survey, located in the centre of a galaxy at redshift z=0.1655. The long rise to absolute magnitude of -20.5 mag, ... More
Discovery of the massive overcontact binary VFTS 352: Evidence for enhanced internal mixingSep 29 2015The contact phase expected to precede the coalescence of two massive stars is poorly characterized due to the paucity of observational constraints. Here we report on the discovery of VFTS 352, an O-type binary in the 30 Doradus region, as the most massive ... More
An eclipsing binary distance to the Large Magellanic Cloud accurate to 2 per centMar 08 2013In the era of precision cosmology it is essential to determine the Hubble Constant with an accuracy of 3% or better. Currently, its uncertainty is dominated by the uncertainty in the distance to the Large Magellanic Cloud (LMC) which as the second nearest ... More
Space-based Microlens Parallax Observation As a Way to Resolve the Severe Degeneracy between Microlens-parallax and Lens-orbital EffectJun 04 2016In this paper, we demonstrate the severity of the degeneracy between the microlens-parallax and lens-orbital effects by presenting the analysis of the gravitational binary-lens event OGLE-2015-BLG-0768. Despite the obvious deviation from the model based ... More
A Venus-Mass Planet Orbiting a Brown Dwarf: Missing Link between Planets and MoonsJul 09 2015Jul 13 2015The co-planarity of solar-system planets led Kant to suggest that they formed from an accretion disk, and the discovery of hundreds of such disks around young stars as well as hundreds of co-planar planetary systems by the Kepler satellite demonstrate ... More
OGLE16aaa - a Signature of a Hungry Super Massive Black HoleJun 09 2016Oct 12 2016We present the discovery and first three months of follow-up observations of a currently on-going unusual transient detected by the OGLE-IV survey, located in the centre of a galaxy at redshift z=0.1655. The long rise to absolute magnitude of -20.5 mag, ... More
Extremely metal-poor stars from the cosmic dawn in the bulge of the Milky WayNov 12 2015The first stars are predicted to have formed within 200 million years after the Big Bang, initiating the cosmic dawn. A true first star has not yet been discovered, although stars with tiny amounts of elements heavier than helium ('metals') have been ... More
OGLE-2015-BLG-0051/KMT-2015-BLG-0048Lb: a Giant Planet Orbiting a Low-mass Bulge Star Discovered by High-cadence Microlensing SurveysJun 30 2016We report the discovery of an extrasolar planet detected from the combined data of a microlensing event OGLE-2015-BLG-0051/KMT-2015-BLG-0048 acquired by two microlensing surveys. Despite that the short planetary signal occurred in the very early Bulge ... More
Reddening and Extinction Toward the Galactic Bulge from OGLE-III: The Inner Milky Way's Rv ~ 2.5 Extinction CurveAug 06 2012Mar 14 2013We combine VI photometry from OGLE-III with VVV and 2MASS measurements of E(J-K_{s}) to resolve the longstanding problem of the non-standard optical extinction toward the Galactic bulge. We show that the extinction is well-fit by the relation A_{I} = ... More
New R Coronae Borealis and DY Persei Star Candidates and Other Related Objects Found in Photometric SurveysJun 25 2014We have carried out a search for new R Coronae Borealis (RCB) variables using the publicly accessible data from various photometric sky surveys and-whenever available-AAVSO visual data. Candidates were selected from Tisserand`s "Catalogue enriched with ... More
The X-Shaped Milky Way Bulge in OGLE-III Photometry and in N-Body ModelsNov 26 2014Dec 15 2014We model the split red clump of the Galactic bulge in OGLE-III photometry, and compare the results to predictions from two N-body models. Our analysis yields precise maps of the brightness of the two red clumps, the fraction of stars in the more distant ... More
MOA-2010-BLG-477Lb: constraining the mass of a microlensing planet from microlensing parallax, orbital motion and detection of blended lightMay 29 2012Microlensing detections of cool planets are important for the construction of an unbiased sample to estimate the frequency of planets beyond the snow line, which is where giant planets are thought to form according to the core accretion theory of planet ... More
OGLE-2014-BLG-1112LB: A Microlensing Brown Dwarf Detected Through the Channel of a Gravitational Binary-Lens EventMay 30 2017Due to the nature depending on only the gravitational field, microlensing, in principle, provides an important tool to detect faint and even dark brown dwarfs. However, the number of identified brown dwarfs is limited due to the difficulty of the lens ... More
A Wide Orbit Exoplanet OGLE-2012-BLG-0838LbJan 16 2019We present the discovery of a planet on a very wide orbit in the microlensing event OGLE-2012-BLG-0838. The signal of the planet is well separated from the main peak of the event and the planet-star projected separation is found to be twice larger than ... More
Discovery of two quasars at $z=5$ from the OGLE SurveyOct 19 2018We have used deep Optical Gravitational Lensing Experiment (OGLE-IV) images ($V \lesssim 23$ mag, $I \lesssim 23$ mag at $3\sigma$) of the Magellanic System, encompassing an area of $\sim$670 deg$^2$, to perform a search for high-$z$ quasar candidates. ... More
Spitzer IRAC Photometry for Time Series in Crowded FieldsAug 31 2015Oct 13 2015We develop a new photometry algorithm that is optimized for $Spitzer$ time series in crowded fields and that is particularly adapted to faint and/or heavily blended targets. We apply this to the 170 targets from the 2015 $Spitzer$ microlensing campaign ... More
OGLE-2017-BLG-1186: first application of asteroseismology and Gaussian processes to microlensingApr 16 2019We present the analysis of the event OGLE-2017-BLG-1186 from the 2017 $Spitzer$ microlensing campaign. This event is remarkable because its source is photometrically variable. We perform an asteroseismic analysis of the source star and find that it is ... More
The OGLE-III planet detection efficiency from six years of microlensing observations (2003 to 2008)Feb 08 2016We use six years (2003 to 2008) of Optical Gravitational Lensing Experiment III microlensing observations to derive the survey detection efficiency for a range of planetary masses and projected distances from the host star. We perform an independent analysis ... More
OGLE-2015-BLG-0196: Ground-based Gravitational Microlens Parallax Confirmed By Space-Based ObservationNov 08 2016In this paper, we present the analysis of the binary gravitational microlensing event OGLE-2015-BLG-0196. The event lasted for almost a year and the light curve exhibited significant deviations from the lensing model based on the rectilinear lens-source ... More
The VLT-FLAMES Tarantula survey XX. The nature of the X-ray bright emission line star VFTS 399Mar 03 2015The stellar population of the 30 Doradus star-forming region in the Large Magellanic Cloud contains a subset of apparently single, rapidly rotating O-type stars. The physical processes leading to the formation of this cohort are currently uncertain. One ... More
MOA 2011-BLG-028Lb: a Neptune-mass Microlensing Planet in the Galactic BulgeDec 10 2015We present the discovery of a Neptune-mass planet orbiting a 0.8 +- 0.3 M_Sun star in the Galactic bulge. The planet manifested itself during the microlensing event MOA 2011-BLG-028/OGLE-2011-BLG-0203 as a low-mass companion to the lens star. The analysis ... More
MOA-2008-BLG-379Lb: A Massive Planet from a High Magnification Event with a Faint SourceNov 14 2013Dec 17 2013We report analysis of high microlensing event MOA-2008-BLG-379, which has a strong microlensing anomaly at its peak, due to a massive planet with a mass ratio of q = 6.9 x 10^{-3}. Because the faint source star crosses the large resonant caustic, the ... More
OGLE-2017-BLG-1522: A giant planet around a brown dwarf located in the Galactic bulgeMar 14 2018We report the discovery of a giant planet in the OGLE-2017-BLG-1522 microlensing event. The planetary perturbations were clearly identified by high-cadence survey experiments despite the relatively short event timescale of $t_{\rm E} \sim 7.5$ days. The ... More
OGLE-2016-BLG-0596Lb: High-Mass Planet From High-Magnification Pure-Survey Microlensing EventJul 17 2016We report the discovery of a high mass-ratio planet $q=0.012$, i.e., 13 times higher than the Jupiter/Sun ratio. The host mass is not presently measured but can be determined or strongly constrained from adaptive optics imaging. The planet was discovered ... More
OGLE-2017-BLG-0373Lb: A Jovian Mass-Ratio Planet Exposes A New Accidental Microlensing DegeneracyFeb 27 2018Apr 05 2018We report the discovery of microlensing planet OGLE-2017-BLG-0373Lb. We show that while the planet-host system has an unambiguous microlens topology, there are two geometries within this topology that fit the data equally well, which leads to a factor ... More
Probing CP Violation in $τ^- \to ν(Kπ/K2π/ 3K/ K3π)^- $ DecaysApr 26 2012Jun 19 2012It had been suggested to probe CP violation in {\tau} \rightarrow {\nu}K{\pi} decays with K0 -K ^{-}0 oscillation to produce ACP({\tau}- \rightarrow {\nu}KS{\pi}-) = (0.36\pm0.01)%. BaBar has found ACP({\tau}- \rightarrow {\nu}KS{\pi}-[\geq {\pi}0]) = ... More