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Incorporating physical source parameters into microlensing modeling
Mateusz J. Mróz, Radosław Poleski, Andrzej Udalski +14
Modeling of complex microlensing events suffers from many difficult-to-disentangle degeneracies. This is especially the case for orbital motion of the source in a binary system, th…
Four-Body Gravitational Microlensing Events Involving Both a Binary Lens and a Binary Source
Cheongho Han, Chung-Uk Lee, Andrzej Udalski +31
We present detailed analyses of three anomalous microlensing events--KMT-2021-BLG-0209, KMT-2021-BLG-0901, and OGLE-2025-BLG-0356--identified from a systematic re-examination of KM…
Candidate Microlensing Brown Dwarfs in Binary Lens Systems from the 2023--2025 Observing Seasons
Cheongho Han, Andrzej Udalski, Ian A. Bond +62
We present detailed light-curve analyses of ten binary-lens microlensing events observed during the 2023--2025 seasons and selected as candidates for hosting brown-dwarf companions…
Six binary brown dwarf candidates identified by microlensing
Cheongho Han, Chung-Uk Lee, Ian A. Bond +57
In this study, we analyze microlensing events from the 2023 and 2024 observing seasons to identify cases likely caused by binary systems composed of BDs. By applying criteria that…
Three binary-source binary-lens microlensing events from the 2024 microlensing campaign
Cheongho Han, Chung-Uk Lee, Andrzej Udalski +27
We investigated microlensing events detected by the OGLE and KMTNet surveys during the 2024 observing season, focusing on those that exhibit very complex anomaly features. Through…
Analyses of anomalous lensing events detected from the UKIRT microlensing survey
Cheongho Han, Weicheng Zang, Andrzej Udalski +61
The United Kingdom Infrared Telescope (UKIRT) microlensing survey was conducted over four years, from 2016 to 2019, with the goal of serving as a precursor to future near-infrared…
KMT-2021-BLG-0284, KMT-2022-BLG-2480, and KMT-2024-BLG-0412: Three microlensing events involving two lens masses and two source stars
Cheongho Han, Andrzej Udalski, Ian A. Bond +59
We carried out a project involving the systematic analysis of microlensing data from the Korea Microlensing Telescope Network survey. The aim of this project is to identify lensing…
Millinovae: A New Class of Transient Supersoft X-ray Sources without a Classical Nova Eruption
Przemek Mróz, Krzysztof Król, Hélène Szegedi +18
Some accreting binary systems containing a white dwarf (such as classical novae or persistent supersoft sources) are seen to emit low-energy X-rays with temperatures of ~10^6 K and…
Microlensing brown-dwarf companions in binaries detected during the 2022 and 2023 seasons
Cheongho Han, Ian A. Bond, Andrzej Udalski +63
Building on previous works to construct a homogeneous sample of brown dwarfs in binary systems, we investigate microlensing events detected by the Korea Microlensing Telescope Netw…
OGLE-2018-BLG-0971, MOA-2023-BLG-065, and OGLE-2023-BLG-0136: Microlensing events with prominent orbital effects
Cheongho Han, Andrzej Udalski, Ian A. Bond +60
We undertake a project to reexamine microlensing data gathered from high-cadence surveys. The aim of the project is to reinvestigate lensing events with light curves exhibiting int…
Observational Parameters of Blue Large-amplitude Pulsators
P. Pietrukowicz, M. Latour, I. Soszynski +15
Blue large-amplitude pulsators (BLAPs) are a recently discovered class of short-period pulsating variable stars. In this work, we present new information on these stars based on ph…
OGLE-2015-BLG-0845L: A low-mass M dwarf from the microlensing parallax and xallarap effects
Zhecheng Hu, Wei Zhu, Andrew Gould +51
We present the analysis of the microlensing event OGLE-2015-BLG-0845, which was affected by both the microlensing parallax and xallarap effects. The former was detected via the sim…
OGLE-2017-BLG-1038: A Possible Brown-dwarf Binary Revealed by Spitzer Microlensing Parallax
Amber Malpas, Michael D. Albrow, Jennifer C. Yee +41
We report the analysis of microlensing event OGLE-2017-BLG-1038, observed by the Optical Gravitational Lensing Experiment, Korean Microlensing Telescope Network, and Spitzer telesc…
OGLE-2018-BLG-0584 and KMT-2018-BLG-2119: two microlensing events with two lens masses and two source stars
Cheongho Han, Andrzej Udalski, Youn Kil Jung +34
We conduct a systematic investigation of the microlensing data collected during the previous observation seasons for the purpose of reanalyzing anomalous lensing events with no sug…
Brown-dwarf companions in microlensing binaries detected during the 2016--2018 seasons
Cheongho Han, Yoon-Hyun Ryu, In-Gu Shin +60
With the aim of finding microlensing binaries containing brown-dwarf (BD) companions, we investigate the microlensing survey data collected during the 2016--2018 seasons. For this…
The OGLE Collection of Variable Stars. Nearly 66,000 Mira stars in the Milky Way
Patryk Iwanek, Igor Soszyński, Szymon Kozłowski +12
We present a collection of 65,981 Mira-type variable stars found in the Optical Gravitational Lensing Experiment (OGLE) project database. Two-thirds of our sample (40,356 objects)…
An Isolated Stellar-Mass Black Hole Detected Through Astrometric Microlensing
Kailash C. Sahu, Jay Anderson, Stefano Casertano +90
We report the first unambiguous detection and mass measurement of an isolated stellar-mass black hole (BH). We used the Hubble Space Telescope (HST) to carry out precise astrometry…
The OGLE Collection of Variable Stars. One Thousand Heartbeat Stars in the Galactic Bulge and Magellanic Clouds
Marcin Wrona, Milena Ratajczak, Piotr A. Kołaczek-Szymański +13
We present a collection of 991 heartbeat star (HBS) candidates found in the Optical Gravitational Lensing Experiment (OGLE) project data archive. We discuss the selection process o…
Photometric Analysis of the OGLE Heartbeat Stars
Marcin Wrona, Piotr A. Kołaczek-Szymański, Milena Ratajczak +1
We present an analysis of 991 heartbeat stars (HBSs) from the OGLE Collection of Variable Stars (OCVS). The sample consists of 512 objects located toward the Galactic bulge (GB), 4…
Using Source Proper Motion to Validate Terrestrial Parallax: OGLE-2019-BLG-1058
In-Gu Shin, Jennifer C. Yee, Kyu-Ha Hwang +30
We show that because the conditions for producing terrestrial microlens parallax (TPRX; i.e., a nearby disk lens) will also tend to produce a large lens-source relative proper moti…
Multiwavelength properties of Miras
Patryk Iwanek, Szymon Kozłowski, Mariusz Gromadzki +12
We comprehensively study the variability of Miras in the Large Magellanic Cloud (LMC) by simultaneous analysing light curves in 14 bands in the range of 0.524 microns. We model…
Binarity as the Origin of Long Secondary Periods in Red Giant Stars
I. Soszyński, A. Olechowska, M. Ratajczak +13
Long secondary periods (LSPs), observed in a third of pulsating red giant stars, are the only unexplained type of large-amplitude stellar variability known at this time. Here we sh…
Over 10 000 Delta Scuti Stars toward the Galactic Bulge from OGLE-IV
P. Pietrukowicz, I. Soszynski, H. Netzel +12
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.…
Mid-Infrared PeriodLuminosity Relations for Miras in the Large Magellanic Cloud
Patryk Iwanek, Igor Soszyński, Szymon Kozłowski
We present the mid-infrared (mid-IR) periodluminosity relations (PLRs) using over 1000 Mira variables in the Large Magellanic Cloud (LMC), for the four Wide-Field Infrared Surve…