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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…
RR Lyrae stars with variable mean magnitudes
Gergely Hajdu, Johanna Jurcsik, Márcio Catelan +6
Context. A number of RR Lyrae stars show variable mean magnitudes in the OGLE survey light curves of the Galactic bulge. Hitherto this phenomenon was not studied, as it was general…
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…
KMT-2022-BLG-0086: Another binary-lens binary-source microlensing event
Sun-Ju Chung, Kyu-Ha Hwang, Jennifer C. Yee +40
We present the analysis of a microlensing event KMT-2022-BLG-0086 of which the overall light curve is not described by a binary-lens single-source (2L1S) model, which suggests the…
KMTNet View of Blue Large-amplitude Pulsators Toward the Galactic Bulge: I. Discovery of Wide-orbit Companions in OGLE-BLAP-006
Seung-Lee Kim, Chung-Uk Lee, Kyeongsoo Hong +6
Blue large-amplitude pulsators (BLAPs), a recently classified type of variable stars, are evolved objects likely formed through interactions between stars in a binary system. Howev…
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…
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…
Improved period variations of 32 contact binaries with rapidly decreasing periods in the Galactic Bulge
Kyeongsoo Hong, Jae Woo Lee, Dong-Jin Kim +4
We present detailed analyses of updated eclipse timing diagrams for 32 contact binary merger candidates in the Galactic bulge. The photometric data was obtained from 2016 to 2021 u…
Brown dwarf companions in binaries detected from the 2021 season high-cadence microlensing surveys
Cheongho Han, Youn Kil Jung, Ian A. Bond +45
As a part of the project aiming to build a homogeneous sample of binary-lens (2L1S) events containing brown-dwarf (BD) companions, we investigate the 2021 season microlensing data…
Probable brown dwarf companions detected in binary microlensing events during the 2018-2020 seasons of the KMTNet survey
Cheongho Han, Youn Kil Jung, Doeon Kim +48
We inspect the microlensing data of the KMTNet survey collected during the 2018--2020 seasons in order to find lensing events produced by binaries with brown-dwarf companions. In o…
Absolute Properties of the Oscillating Eclipsing Algol X Trianguli
Jae Woo Lee, Kyeongsoo Hong, Jang-Ho Park +2
We report results from the TESS photometric data and new high-resolution spectra of the Algol system X Tri showing short-period pulsations. From the echelle spectra, the radial vel…
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…
KMT-2021-BLG-1122L: The first microlensing triple stellar system
Cheongho Han, Youn Kil Jung, Andrew Gould +19
We systematically inspect the microlensing data acquired by the KMTNet survey during the previous seasons in order to find anomalous lensing events for which the anomalies in the l…
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…
The Astrometric Animation of Water Masers towards the Mira Variable BX Cam
Shuangjing Xu, Hiroshi Imai, Youngjoo Yun +20
We report VLBI monitoring observations of the 22 GHz water (HO) masers around the Mira variable BX Cam, which were carried out as a part of the EAVN Synthesis of Stellar Mase…
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…
Period Changes of 14,127 Contact Eclipsing Binaries in the Galactic Bulge
Kyeongsoo Hong, Jae Woo Lee, Jang-Ho Park +5
We present the orbital period variations of 14,127 contact eclipsing binaries (CEBs) based on the OGLE-III\&IV observations in the Galactic bulge. New times of minimum lights for t…
Pulsation and Rotation of the EL CVn-type Eclipsing Binary 1SWASP J024743.37-251549.2
Seung-Lee Kim, Jae Woo Lee, Chung-Uk Lee +6
EL CVn-type eclipsing binaries are composed of a massive A-type main-sequence primary star and a hotter B-type secondary star. This paper presents the time-series photometric and a…
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…
KMT-2019-BLG-0797: binary-lensing event occurring on a binary stellar system
Cheongho Han, Chung-Uk Lee, Yoon-Hyun Ryu +18
We analyze the microlensing event KMT-2019-BLG-0797. The light curve of the event exhibits two anomalous features from a single-lens single-source model, and we aim to reveal the n…
OGLE-2018-BLG-1269Lb: A Jovian Planet With A Bright, Host
Youn Kil Jung, Andrew Gould, Andrzej Udalski +54
We report the discovery of a planet in the microlensing event OGLE-2018-BLG-1269, with planet-host mass ratio , i.e., times smaller than the Jupiter/Su…
Asymmetric distributions of H2O and SiO masers towards V627 Cas
Haneul Yang, Se-Hyung Cho, Youngjoo Yun +7
We performed simultaneous observations of the H2O 6(1,6) - 5(2,3) (22.235080 GHz) and SiO v= 1, 2, J = 1 - 0, SiO v = 1, J = 2 - 1, 3 - 2 (43.122080, 42.820587, 86.243442, and 129.…
Candidate Brown-dwarf Microlensing Events with Very Short Timescales and Small Angular Einstein Radii
Cheongho Han, Chung-Uk Lee, Andrzej Udalski +62
Short-timescale microlensing events are likely to be produced by substellar brown dwarfs (BDs), but it is difficult to securely identify BD lenses based on only event timescales $t…