Browsing by Author "Li MCA"

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    An analysis of binary microlensing event OGLE-2015-BLG-0060
    (Oxford University Press on behalf of the Royal Astronomical Society, 2019-08) Tsapras Y; Cassan A; Ranc C; Bachelet E; Street R; Udalski A; Hundertmark M; Bozza V; Beaulieu JP; Marquette JB; Euteneuer E; Bramich DM; Dominik M; Figuera Jaimes R; Horne K; Mao S; Menzies J; Schmidt R; Snodgrass C; Steele IA; Wambsganss J; Mróz P; Szymański MK; Soszyński I; Skowron J; Pietrukowicz P; Kozłowski S; Poleski R; Ulaczyk K; Pawlak M; Jørgensen UG; Skottfelt J; Popovas A; Ciceri S; Korhonen H; Kuffmeier M; Evans DF; Peixinho N; Hinse TC; Burgdorf MJ; Southworth J; Tronsgaard R; Kerins E; Andersen MI; Rahvar S; Wang Y; Wertz O; Rabus M; Calchi Novati S; D'Ago G; Scarpetta G; Mancini L; Abe F; Asakura Y; Bennett DP; Bhattacharya A; Donachie M; Evans P; Fukui A; Hirao Y; Itow Y; Kawasaki K; Koshimoto N; Li MCA; Ling CH; Masuda K; Matsubara Y; Muraki Y; Miyazaki S; Nagakane M; Ohnishi K; Rattenbury N; Saito T; Sharan A; Shibai H; Sullivan DJ; Sumi T; Suzuki D; Tristram PJ; Yamada T; Yonehara A; The RoboNet team; The OGLE collaboration; The MiNDSTEp collaboration; The MOA collaboration
    We 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 from the robotic telescopes of the Las Cumbres Observatory. We show that, for the first time, all main features of an anomalous microlensing event are well covered by follow-up data, allowing us to estimate the physical parameters of the lens. The strong detection of second-order effects in the event light curve necessitates the inclusion of longer-baseline survey data in order to constrain the parallax vector. We find that the event was most likely caused by a stellar binary-lens with masses M = 0.87 pm 0.12 mathrm{M} and M = 0.77 pm 0.11 mathrm{M}. The distance to the lensing system is 6.41 ± 0.14 kpc and the projected separation between the two components is 13.85 ± 0.16 au. Alternative interpretations are also considered.
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    KMT-2019-BLG-1715: Planetary microlensing event with three lens masses and two source stars
    (IOP Publishing on behalf of the American Astronomical Society, 2021-06-01) Han C; Udalski A; Kim D; Jung YK; Lee C-U; Bond IA; Albrow MD; Chung S-J; Gould A; Hwang K-H; Kim H-W; Ryu Y-H; Shin I-G; Shvartzvald Y; Zang W; Yee JC; Cha S-M; Kim D-J; Kim S-L; Lee D-J; Lee Y; Park B-G; Pogge RW; Kim C-H; Kim W-T; Mróz P; Szymański MK; Skowron J; Poleski R; Soszyński I; Pietrukowicz P; Kozłowski S; Ulaczyk K; Rybicki KA; Iwanek P; Wrona M; Gromadzki M; Abe F; Barry R; Bennett DP; Bhattacharya A; Donachie M; Fujii H; Fukui A; Itow Y; Hirao Y; Kirikawa R; Kondo I; Li MCA; Matsubara Y; Muraki Y; Miyazaki S; Ranc C; Rattenbury NJ; Satoh Y; Shoji H; Suematsu H; Sumi T; Suzuki D; Tanaka Y; Tristram PJ; Yamakawa T; Yamawaki T; Yonehara A
    We investigate the gravitational microlensing event KMT-2019-BLG-1715, the light curve of which shows two short-term anomalies from a caustic-crossing binary-lensing light curve: one with a large deviation and the other with a small deviation. We identify five pairs of solutions, in which the anomalies are explained by adding an extra lens or source component in addition to the base binary-lens model. We resolve the degeneracies by applying a method in which the measured flux ratio between the first and second source stars is compared with the flux ratio deduced from the ratio of the source radii. Applying this method leaves a single pair of viable solutions, in both of which the major anomaly is generated by a planetary-mass third body of the lens, and the minor anomaly is generated by a faint second source. A Bayesian analysis indicates that the lens comprises three masses: a planet-mass object with ∼2.6 MJ and binary stars of K and M dwarfs lying in the galactic disk. We point out the possibility that the lens is the blend, and this can be verified by conducting high-resolution follow-up imaging for the resolution of the lens from the source.
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    Systematic reanalysis of KMTNet microlensing events, paper I: Updates of the photometry pipeline and a new planet candidate
    (Oxford University Press on behalf of the Royal Astronomical Society., 2024-02-01) Yang H; Yee JC; Hwang K-H; Qian Q; Bond IA; Gould A; Hu Z; Zhang J; Mao S; Zhu W; Albrow MD; Chung S-J; Kim S-L; Park B-G; Han C; Jung YK; Ryu Y-H; Shin I-G; Shvartzvald Y; Cha S-M; Kim D-J; Kim H-W; Lee C-U; Lee D-J; Lee Y; Pogge RW; Zang W; Abe F; Barry R; Bennett DP; Bhattacharya A; Donachie M; Fujii H; Fukui A; Hirao Y; Itow Y; Kirikawa R; Kondo I; Koshimoto N; Silva SI; Li MCA; Matsubara Y; Muraki Y; Suzuki D; Tristram PJ; Yonehara A; Ranc C; Miyazaki S; Olmschenk G; Rattenbury NJ; Satoh Y; Shoji H; Sumi T; Tanaka Y; Yamawaki T
    In this work, we update and develop algorithms for KMTNet tender-love care (TLC) photometry in order to create a new, mostly automated, TLC pipeline. We then start a project to systematically apply the new TLC pipeline to the historic KMTNet microlensing events, and search for buried planetary signals. We report the discovery of such a planet candidate in the microlensing event MOA-2019-BLG-421/KMT-2019-BLG-2991. The anomalous signal can be explained by either a planet around the lens star or the orbital motion of the source star. For the planetary interpretation, despite many degenerate solutions, the planet is most likely to be a Jovian planet orbiting an M or K dwarf, which is a typical microlensing planet. The discovery proves that the project can indeed increase the sensitivity of historic events and find previously undiscovered signals.