Browsing by Author "Ratajczak, M."

Now showing 1 - 6 of 6
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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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    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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    Orbital and physical parameters of eclipsing binaries from the All-Sky Automated Survey catalogue - IV. A 0.61+0.45 M⊙ binary in a multiple system
    (2012) Helminiak, K. G.; Konacki, M.; Rozyczka, M.; Kaluzny, J.; Ratajczak, M.; Borkowski, J.; Sybilski, P.; Muterspaugh, M. W.; Reichart, D. E.; Ivarsen, K. M.; Haislip, J. B.; Crain, J. A.; Foster, A. C.; Nysewander, M. C.; LaCluyze, A. P.
    We present the orbital and physical parameters of a newly discovered low-mass detached eclipsing binary from the All-Sky Automated Survey (ASAS) data base: ASAS J0113283821.1 A, which is a member of a visual binary system with the secondary component separated by about 1.4 arcsec. The radial velocities have been calculated from the high-resolution spectra obtained with the 1.9-m Radcliffe telescope/Grating Instrument for Radiation Analysis with a Fibre-Fed Echelle (GIRAFFE) spectrograph, the 3.9-m Anglo-Australian Telescope (AAT)/University College London Echelle Spectrograph (UCLES) and the 3.0-m Shane telescope/Hamilton Spectrograph (HamSpec) on the basis of the todcor technique and the positions of the Ha emission lines. For the analysis, we have used V- and I-band photometry obtained with the 1.0-m Elizabeth telescope and the 0.41-m Panchromatic Robotic Optical Monitoring and Polarimetry Telescopes (PROMPT), supplemented with the publicly available ASAS light curve of the system. We have found that ASAS J0113283821.1 A is composed of two late-type dwarfs, which have masses of M1 = 0.612 +/- 0.030 M? and M2 = 0.445 +/- 0.019 M? and radii of R1 = 0.596 +/- 0.020 R? and R2 = 0.445 +/- 0.024 R?. Both show a substantial level of activity, which manifests in strong Ha and H beta emission and the presence of cool spots. The influence of the third light on the eclipsing pair properties has also been evaluated and the photometric properties of component B have been derived. A comparison with several popular stellar evolution models shows that the system is on its main-sequence evolution stage and that it is probably more metal-rich than the Sun. We have also found several clues to suggest that component B itself is a binary composed of two nearly identical similar to 0.5-M? stars.
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    Orbital and physical parameters of eclipsing binaries from the all-sky automated survey catalogue: VI. AK fornacis: A rare, bright K-type eclipsing binary
    (2014) Helminiak, Krzysztof Grzegorz; Brahm, R.; Espinoza, N.; Ratajczak, M.; Jordán Colzani, Andrés Cristóbal; Konacki, M.; Rabus, Markus
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    Orbital and physical parameters of eclipsing binaries from the ASAS catalogue - VII. V1200 centauri: a bright triple in the Hyades moving group
    (2015) Coronado, Johanna; Helminiak, Krzysztof Grzegorz; Vanzi, Leonardo; Espinoza Pérez, Néstor; Brahm Scott, Rafael; Jordán Colzani, Andrés Cristóbal; Catelan, Márcio; Ratajczak, M.; Konacki, Maciej