Browsing by Author "Rybicki, K. A."

Now showing 1 - 4 of 4
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    A Close Binary Lens Revealed by the Microlensing Event Gaia20bof
    (2024) Bachelet, E.; Rota, P.; Bozza, V.; Zielinski, P.; Tsapras, Y.; Hundertmark, M.; Wambsganss, J.; Wyrzykowski, L.; Mikolajczyk, P. J.; Street, R. A.; Jaimes, R. Figuera; Cassan, A.; Dominik, M.; Buckley, D. A. H.; Awiphan, S.; Nakhaharutai, N.; Zola, S.; Rybicki, K. A.; Gromadzki, M.; Howil, K.; Ihanec, N.; Jablonska, M.; Kruszynska, K.; Pylypenko, U.; Ratajczak, M.; Sitek, M.; Rabus, M.
    During the last 25 yr, hundreds of binary stars and planets have been discovered toward the Galactic bulge by microlensing surveys. Thanks to a new generation of large-sky surveys, it is now possible to regularly detect microlensing events across the entire sky. The OMEGA Key Projet at the Las Cumbres Observatory carries out automated follow-up observations of microlensing events alerted by these surveys with the aim of identifying and characterizing exoplanets as well as stellar remnants. In this study, we present the analysis of the binary lens event Gaia20bof. By automatically requesting additional observations, the OMEGA Key Project obtained dense time coverage of an anomaly near the peak of the event, allowing characterization of the lensing system. The observed anomaly in the lightcurve is due to a binary lens. However, several models can explain the observations. Spectroscopic observations indicate that the source is located at <= 2.0 kpc, in agreement with the parallax measurements from Gaia. While the models are currently degenerate, future observations, especially the Gaia astrometric time series as well as high-resolution imaging, will provide extra constraints to distinguish between them.
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    Gaia21blx: Complete resolution of a binary microlensing event in the Galactic disk
    (2024) Rota, P.; Bozza, V.; Hundertmark, M.; Bachelet, E.; Street, R.; Tsapras, Y.; Cassan, A.; Dominik, M.; Jaimes, R. Figuera; Rybicki, K. A.; Wambsganss, J.; Wyrzykowski, L.; Zielinski, P.; Bonavita, M.; Hinse, T. C.; Jorgensen, U. G.; Khalouei, E.; Korhonen, H.; Longa-Pena, P.; Peixinho, N.; Rahvar, S.; Sajadian, S.; Skottfelt, J.; Snodgrass, C.; Tregolan-Reed, J.
    Context. Gravitational microlensing is a method that is used to discover planet-hosting systems at distances of several kiloparsec in the Galactic disk and bulge. We present the analysis of a microlensing event reported by the Gaia photometric alert team that might have a bright lens. Aims. In order to infer the mass and distance to the lensing system, the parallax measurement at the position of Gaia21blx was used. In this particular case, the source and the lens have comparable magnitudes and we cannot attribute the parallax measured by Gaia to the lens or source alone. Methods. Since the blending flux is important, we assumed that the Gaia parallax is the flux-weighted average of the parallaxes of the lens and source. Combining this assumption with the information from the microlensing models and the finite source effects we were able to resolve all degeneracies and thus obtained the mass, distance, luminosities and projected kinematics of the binary lens and the source. Results. According to the best model, the lens is a binary system at 2.18 +/- 0.07 kpc from Earth. It is composed of a G star with 0.95 +/- 0.17 M-circle dot and a K star with 0.53 +/- 0.07 M-circle dot. The source is likely to be an F subgiant star at 2.38 +/- 1.71 kpc with a mass of 1.10 +/- 0.18 M-circle dot. Both lenses and the source follow the kinematics of the thin-disk population. We also discuss alternative models, that are disfavored by the data or by prior expectations, however.
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    Gaia22dkvLb: A Microlensing Planet Potentially Accessible to Radial-velocity Characterization
    (2024) Wu, Zexuan; Dong, Subo; Yi, Tuan; Liu, Zhuokai; El-Badry, Kareem; Gould, Andrew; Wyrzykowski, L.; Rybicki, K. A.; Bachelet, Etienne; Christie, Grant W.; de Almeida, L.; Monard, L. A. G.; McCormick, J.; Natusch, Tim; Zielinski, P.; Chen, Huiling; Huang, Yang; Liu, Chang; Merand, A.; Mroz, Przemek; Shangguan, Jinyi; Udalski, Andrzej; Woillez, J.; Zhang, Huawei; Hambsch, Franz-Josef; Mikolajczyk, P. J.; Gromadzki, M.; Ratajczak, M.; Kruszynska, Katarzyna; Ihanec, N.; Pylypenko, Uliana; Sitek, M.; Howil, K.; Zola, Staszek; Michniewicz, Olga; Zejmo, Michal; Lewis, Fraser; Bronikowski, Mateusz; Potter, Stephen; Andrzejewski, Jan; Merc, Jaroslav; Street, Rachel; Fukui, Akihiko; Jaimes, R. Figuera; Bozza, V.; Rota, P.; Cassan, A.; Dominik, M.; Tsapras, Y.; Hundertmark, M.; Wambsganss, J.; Bakowska, K.; Slowikowska, A.
    We report discovering an exoplanet from following up a microlensing event alerted by Gaia. The event Gaia22dkv is toward a disk source rather than the traditional bulge microlensing fields. Our primary analysis yields a Jovian planet with Mp=0.59-0.05+0.15MJ at a projected orbital separation r perpendicular to=1.4-0.3+0.8 au, and the host is a similar to 1.1 M circle dot turnoff star at similar to 1.3 kpc. At r 'approximate to 14 , the host is far brighter than any previously discovered microlensing planet host, opening up the opportunity to test the microlensing model with radial velocity (RV) observations. RV data can be used to measure the planet's orbital period and eccentricity, and they also enable searching for inner planets of the microlensing cold Jupiter, as expected from the "inner-outer correlation" inferred from Kepler and RV discoveries. Furthermore, we show that Gaia astrometric microlensing will not only allow precise measurements of its angular Einstein radius theta E but also directly measure the microlens parallax vector and unambiguously break a geometric light-curve degeneracy, leading to the definitive characterization of the lens system.
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    Precision measurement of a brown dwarf mass in a binary system in the microlensing event OGLE-2019-BLG-0033/MOA-2019-BLG-035
    (2022) Herald, A.; Udalski, A.; Bozza, V.; Rota, P.; Bond, I. A.; Yee, J. C.; Sajadian, S.; Mroz, P.; Poleski, R.; Skowron, J.; Szymanski, M. K.; Soszynski, I.; Pietrukowicz, P.; Kozlowski, S.; Ulaczyk, K.; Rybicki, K. A.; Iwanek, P.; Wrona, M.; Gromadzki, M.; Abe, F.; Barry, R.; Bennett, D. P.; Bhattacharya, A.; Fukui, A.; Fujii, H.; Hirao, Y.; Itow, Y.; Kirikawa, R.; Kondo, I.; Koshimoto, N.; Matsubara, Y.; Matsumoto, S.; Miyazaki, S.; Muraki, Y.; Olmschenk, G.; Ranc, C.; Okamura, A.; Rattenbury, N. J.; Satoh, Y.; Sumi, T.; Suzuki, D.; Silva, S. Ishitani; Toda, T.; Tristram, P. J.; Vandorou, A.; Yama, H.; Beichman, C. A.; Bryden, G.; Novati, S. Calchi; Carey, S.; Gaudi, B. S.; Gould, A.; Henderson, C. B.; Johnson, S.; Shvartzvald, Y.; Zhu, W.; Dominik, M.; Hundertmark, M.; Jorgensen, U. G.; Longa-Pena, P.; Skottfelt, J.; Tregloan-Reed, J.; Bach-Moller, N.; Burgdorf, M.; D'Ago, G.; Haikala, L.; Hitchcock, J.; Khalouei, E.; Peixinho, N.; Rahvar, S.; Snodgrass, C.; Southworth, J.; Spyratos, P.; Zang, W.; Yang, H.; Mao, S.; Bachelet, E.; Maoz, D.; Street, R. A.; Tsapras, Y.; Christie, G. W.; Cooper, T.; de Almeida, L.; do Nascimento, J. -D., Jr.; Green, J.; Han, C.; Hennerley, S.; Marmont, A.; McCormick, J.; Monard, L. A. G.; Natusch, T.; Pogge, R.
    Context. Brown dwarfs are transition objects between stars and planets that are still poorly understood, for which several competing mechanisms have been proposed to describe their formation. Mass measurements are generally difficult to carry out for isolated objects as well as for brown dwarfs orbiting low-mass stars, which are often too faint for a spectroscopic follow-up.