Browsing by Author "Bozza, V."

Now showing 1 - 20 of 30
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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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    A super-jupiter orbiting a late-type star : a refined analysis of microlensing event OGLE-2012-BLG-0406
    (2014) Tsapras, Y.; Choi, J.-Y; Street, R.; Han, C.; Bozza, V.; Gould, A.; Dominik, M.; Beaulieu, J. P.; Udalski, A.; Rabus, Markus
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    An analysis of binary microlensing event OGLE-2015-BLG-0060
    (2019) Tsapras, Y.; Cassan, A.; Ranc, C.; Bachelet, E.; Street, R.; Udalski, A.; Hundertmark, M.; Bozza, V.; Beaulieu, J. P.; Rabus, Markus; Marquette, J. B.; Euteneuer, E.; Bramich, D. M.; Dominik, M.; Jaimes, R. F.; Horne, K.; Mao, S.; Menzies, J.; Schmidt, R.; Snodgrass, C.; Steele, I. A.; Wambsganss, J.; Mroz, P.; Szymanski, M. K.; Soszynski, I.; Skowron, J.; Pietrukowicz, Pawel; Kozlowski, S.; Poleski, R.; Ulaczyk, K.; Pawlak, M.; Jorgensen, U. G.; Skottfelt, J.; Popovas, A.; Ciceri, S.; Korhonen, H.; Kuffmeier, M.; Evans, D. F.; Peixinho, N.; Hinse, T. C.; Burgdorf, M. J.; Southworth, J.; Tronsgaard, R.; Kerins, E.; Andersen, M. I.; Rahvar, S.; Wang, Y.; Wertz, O.; Novati, S. C.; D'Ago, G.; Scarpetta, G.; Mancini, L.; Abe, F.; Asakura, Y.; Bennett, D. P.; Bhattacharya, A.; Donachie, M.; Evans, P.; Fukui, A.; Hirao, Y.; Itow, Y.; Kawasaki, K.; Koshimoto, N.; Li, M. C. A.; Ling, C. H.; Masuda, K.; Matsubara, Y.; Muraki, Y.; Miyazaki, S.; Nagakane, M.; Ohnishi, K.; Rattenbury, N.; Saito, T.; Sharan, A.; Shibai, H.; Sullivan, D. J.; Sumi, T.; Suzuki, D.; Tristram, P. J.; Yamada, T.; Yonehara, A.
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    Digging deeper into the dense Galactic globular cluster Terzan 5 with electron-multiplying CCDs Variable star detection and new discoveries
    (2024) Jaimes, R. Figuera; Catelan, M.; Horne, K.; Skottfelt, J.; Snodgrass, C.; Dominik, M.; Jorgensen, U. G.; Southworth, J.; Hundertmark, M.; Longa-Pena, P.; Sajadian, S.; Tregolan-Reed, J.; Hinse, T. C.; Andersen, M. I.; Bonavita, M.; Bozza, V.; Burgdorf, M. J.; Haikala, L.; Khalouei, E.; Korhonen, H.; Peixinho, N.; Rabus, M.; Rahvar, S.
    Context. High frame-rate imaging was employed to mitigate the effects of atmospheric turbulence (seeing) in observations of globular cluster Terzan 5.
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    EMCCD photometry reveals two new variable stars in the crowded central region of the globular cluster NGC 6981 (Research Note)
    (2013) Skottfelt, J.; Rabus, Markus; Bramich, D.M.; Figuera Jaimes, R.; Jørgensen, U.G.; Kains, N.; Harpsøe, K.B.W.; Liebig, C.; Penny, M.T.; Alsubai, K.A.; Andersen, J.M.; Bozza, V.; Browne, P.; Calchi Novati, S.; Damerdji, Y.; Diehl, C.; Dominik, M.; Elyiv, A.; Giannini, E.; Hessman, F.; Hinse, T.C.; Hundertmark, M.; Juncher, D.; Kerins, E.; Korhonen, H.; Mancini, L.; Martin, R.; Rahvar, S.; Scarpetta, G.; Southworth, J.; Snodgrass, C.; Street, R.A.; Surdej, J.; Tregloan-Reed, J.; Vilela, C.; Williams, A.
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    Erratum : A. detailed census of variable stars in the globular cluster NGC. 6333 (M9) from CCD. differential photometry
    (2016) Ferro, A.; Bramich, D.; Jaimes, R.; Giridhar, S.; Kains, N.; Kuppuswamy, K.; Jorgensen, U.; Alsubai, K.; Andersen, J.; Rabus, Markus; Bozza, V.; Novati, S.; Damerdji, Y.; Diehl, C.; Dreizler, S.; Elyiv, A.
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    Exploring the crowded central region of ten Galactic globular clusters using EMCCDs Variable star searches and new discoveries
    (2016) Jaimes, R.; Bramich, D.; Skottfelt, J.; Kains, N.; Jorgensen, U.; Horne, K.; Dominik, M.; Alsubai, K.; Bozza, V.; Rabus, Markus; Novati, S.; Ciceri, S.; D'Ago, G.; Galianni, P.; Gu, S.
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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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    High-precision photometry by telescope defocusing – VII. The ultrashort period planet WASP-103
    (2015) Southworth, J.; Mancini, L.; Ciceri, S.; Budaj, J.; Dominik, M.; Jaimes, R.; Haugbolle, T.; Jorgensen, U.; Popovas, A.; Rabus, Markus; Rahvar, S.; Von Essen, C.; Schmidt, R.; Wertz, O.; Bozza, V.; Novati, S.
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    High-resolution Imaging of Transiting Extrasolar Planetary systems (HITEP) I. Lucky imaging observations of 101 systems in the southern hemisphere
    (2016) Evans, D.; Southworth, J.; Maxted, P.; Skottfelt, J.; Hundertmark, M.; Jorgensen, U.; Dominik, M.; Alsubai, K.; Andersen, M.; Rabus, Markus; Burgdorf, M.; Ciceri, S.; Jaimes, R.; Gu, S.; Haugbolle, T.; Bozza, V.
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    High-resolution imaging of transiting extrasolar planetary systems (HITEP) II. Lucky imaging results from 2015 and 2016
    (2018) Evans, D. F.; Southworth, J.; Smalley, B.; Jørgensen, U.G.; Dominik, M.; Andersen, M.I.; Bozza, V.; Bramich, D.M.; Burgdorf, M.J.; Rabus, Markus
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    Many new variable stars discovered in the core of the globular cluster NGC. 6715 (M54) with EMCCD. observations
    (2016) Starkey, D.; Street, R.; Surdej, J.; Tronsgaard, R.; Unda-Sanzana, E.; Von Essen, C.; Wang, X.; Wertz, O.; Figuera Jaimes, R.; Rabus, Markus; Bramich, D.; Kains, N.; Skottfelt, J.; Jorgensen, U.; Horne, K.; Dominik, M.; Alsubai, K.; Bozza, V.; Burgdorf, M.; Calchi Novati, S.; Ciceri, S..
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    MASS. MEASUREMENTS. OF. ISOLATED. OBJECTS. FROM. SPACE-BASED. MICROLENSING
    (2016) Zhu, W.; Novati, S.; Gould, A.; Udalski, A.; Han, C.; Shvartzvald, Y.; Ranc, C.; Jorgensen, U.; Poleski, R.; Rabus, Markus; Bozza, V.; Beichman, C.; Bryden, G.; Carey, S.; Gaudi, B.; Henderson, C.
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    MiNDSTEp differential photometry of the gravitationally lensed quasars WFI 2033-4723 and HE 0047-1756: microlensing and a new time delay
    (2017) Giannini, E.; Schmidt, R. W.; Wambsganss, J.; Alsubai, K.; Andersen, J. M.; Anguita, T.; Bozza, V.; Bramich, D. M.; Browne, P.; Rabus, Markus
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    OGLE-2014-BLG-1186 : gravitational microlensing providing evidence for a planet orbiting the foreground star or for a close binary source?
    (2019) Dominik, M.; Bachelet, E.; Bozza, V.; Street, R.A.; Han, C.; Hundertmark, M.; Udalski, A.; Bramich, D.M; Alsubai, K.A.; Rabus, Markus; Novati, S.C.; Ciceri, S.; D'Ago, G.; Jaimes, R.F.; Haugbolle, T.; Hinse, T.C.; Horne, K.; Jorgensen, U.G.; Juncher, D.; Kains, N.; Korhonen, H.
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    OGLE-2017-BLG-0329L : a microlensing binary characterized with dramatically enhanced precision using data from space-based observations
    (2018) Han, C.; Calchi Novati, S.; Udalski, A.; Lee, C.U.; Gould, A.; Bozza, V.; Mróz, P.; Pietrukowicz, Pawel; Skowron, J.; Rabus, Markus
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    OGLE-2018-BLG-0022 : A Nearby M-dwarf Binary
    (2019) Street, R.A.; Bachelet, E.; Tsapras, Y.; Hundertmark, M.P.G.; Bozza, V.; Dominik, M.; Bramich, D.M.; Cassan, A.; Horne, K.; Rabus, Markus; Mao, S.; Saha, A.; Wambsganss, J.; Zang, WC; Jorgensen, UG
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    Orbital alignment and star-spot properties in the WASP-52 planetary system
    (OXFORD UNIV PRESS, 2017) Mancini, L.; Southworth, J.; Raia, G.; Tregloan Reed, J.; Molliere, P.; Bozza, V.; Bretton, M.; Bruni, I.; Ciceri, S.; D'Ago, G.; Dominik, M.; Hinse, T. C.; Hundertmark, M.; Jorgensen, U. G.; Korhonen, H.; Rabus, M.; Rahvar, S.; Starkey, D.; Novati, S. Calchi; Jaimes, R. Figuera; Henning, Th.; Juncher, D.; Haugbolle, T.; Kains, N.; Popovas, A.; Schmidt, R. W.; Skottfelt, J.; Snodgrass, C.; Surdej, J.; Wertz, O.
    We report 13 high-precision light curves of eight transits of the exoplanet WASP-52 b, obtained by using four medium-class telescopes, through different filters, and adopting the defocussing technique. One transit was recorded simultaneously from two different observatories and another one from the same site but with two different instruments, including a multiband camera. Anomalies were clearly detected in five light curves and modelled as star-spots occulted by the planet during the transit events. We fitted the clean light curves with the JKTEBOP code, and those with the anomalies with the PRISM + GEMC codes in order to simultaneously model the photometric parameters of the transits and the position, size and contrast of each star-spot. We used these new light curves and some from the literature to revise the physical properties of the WASP-52 system. Star-spots with similar characteristics were detected in four transits over a period of 43 d. In the hypothesis that we are dealing with the same star-spot, periodically occulted by the transiting planet, we estimated the projected orbital obliquity of WASP-52 b to be. = 3 degrees.8 +/- 8 degrees.4. We also determined the true orbital obliquity, psi = 20 degrees +/- 50 degrees, which is, although very uncertain, the first measurement of. purely from star-spot crossings. We finally assembled an optical transmission spectrum of the planet and searched for variations of its radius as a function of wavelength. Our analysis suggests a flat transmission spectrum within the experimental uncertainties.