Browsing by Author "Novati, S. Calchi"

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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.
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    PATHWAY TO THE GALACTIC DISTRIBUTION OF PLANETS: COMBINED SPITZER AND GROUND-BASED MICROLENS PARALLAX MEASUREMENTS OF 21 SINGLE-LENS EVENTS
    (2015) Novati, S. Calchi; Gould, A.; Udalski, A.; Menzies, J. W.; Bond, I. A.; Shvartzvald, Y.; Street, R. A.; Hundertmark, M.; Beichman, C. A.; Yee, J. C.; Carey, S.; Poleski, R.; Skowron, J.; Kozlowski, S.; Mroz, P.; Pietrukowicz, P.; Pietrzynski, G.; Szymanski, M. K.; Soszynski, I.; Ulaczyk, K.; Wyrzykowski, L.; Albrow, M.; Beaulieu, J. P.; Caldwell, J. A. R.; Cassan, A.; Coutures, C.; Danielski, C.; Prester, D. Dominis; Donatowicz, J.; Loncaric, K.; McDougall, A.; Morales, J. C.; Ranc, C.; Zhu, W.; Abe, F.; Barry, R. K.; Bennett, D. P.; Bhattacharya, A.; Fukunaga, D.; Inayama, K.; Koshimoto, N.; Namba, S.; Sumi, T.; Suzuki, D.; Tristram, P. J.; Wakiyama, Y.; Yonehara, A.; Maoz, D.; Kaspi, S.; Friedmann, M.; Bachelet, E.; Jaimes, R. Figuera; Bramich, D. M.; Tsapras, Y.; Horne, K.; Snodgrass, C.; Wambsganss, J.; Steele, I. A.; Kains, N.; Bozza, V.; Dominik, M.; Jorgensen, U. G.; Alsubai, K. A.; Ciceri, S.; D'Ago, G.; Haugbolle, T.; Hessman, F. V.; Hinse, T. C.; Juncher, D.; Korhonen, H.; Mancini, L.; Popovas, A.; Rabus, M.; Rahvar, S.; Scarpetta, G.; Schmidt, R. W.; Skottfelt, J.; Southworth, J.; Starkey, D.; Surdej, J.; Wertz, O.; Zarucki, M.; Gaudi, B. S.; Pogge, R. W.; De Poy, D. L.
    We present microlens parallax measurements for 21 (apparently) isolated lenses observed toward the Galactic bulge that were imaged simultaneously from Earth and Spitzer, which was similar to 1 AU west of Earth in projection. We combine these measurements with a kinematic model of the Galaxy to derive distance estimates for each lens, with error bars that are small compared to the Sun's galactocentric distance. The ensemble therefore yields a well-defined cumulative distribution of lens distances. In principle, it is possible to compare this distribution against a set of planets detected in the same experiment in order to measure the Galactic distribution of planets. Since these Spitzer observations yielded only one planet, this is not yet possible in practice. However, it will become possible as larger samples are accumulated.
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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.
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    SPITZER. OBSERVATIONS. OF. OGLE-2015-BLG-1212 REVEAL. A. NEW. PATH. TOWARD. BREAKING. STRONG. MICROLENS. DEGENERACIES
    (2016) Bozza, V.; Shvartzvald, Y.; Udalski, A.; Novati, S. Calchi; Bond, I. A.; Han, C.; Hundertmark, M.; Poleski, R.; Pawlak, M.; Rabus, Markus
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    SPITZER. PARALLAX. OF. OGLE-2015-BLG-0966 : A. COLD. NEPTUNE. IN. THE. GALACTIC. DISK
    (2016) Street, R. A.; Udalski, A.; Novati, S. Calchi; Hundertmark, M. P. G.; Zhu, W.; Gould, A.; Yee, J.; Tsapras, Y.; Bennett, D. P.; Rabus, Markus
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    THE FIRST SIMULTANEOUS MICROLENSING OBSERVATIONS BY TWO SPACE TELESCOPES: SPITZER AND SWIFT REVEAL A BROWN DWARF IN EVENT OGLE-2015-BLG-1319
    (2016) Shvartzvald, Y.; Li, Z.; Udalski, A.; Gould, A.; Sumi, T.; Street, R. A.; Novati, S. Calchi; Hundertmark, M.; Bozza, V.; Beichman, C.; Bryden, G.; Carey, S.; Drummond, J.; Fausnaugh, M.; Gaudi, B. S.; Henderson, C. B.; Tan, T. G.; Wibking, B.; Pogge, R. W.; Yee, J. C.; Zhu, W.; Tsapras, Y.; Bachelet, E.; Dominik, M.; Bramich, D. M.; Cassan, A.; Jaimes, R. Figuera; Horne, K.; Ranc, C.; Schmidt, R.; Snodgrass, C.; Wambsganss, J.; Steele, I. A.; Menzies, J.; Mao, S.; Poleski, R.; Pawlak, M.; Szymanski, M. K.; Skowron, J.; Mroz, P.; Kozlowski, S.; Wyrzykowski, L.; Pietrukowicz, P.; Soszynski, I.; Ulaczyk, K.; Abe, F.; Asakura, Y.; Barry, R. K.; Bennett, D. P.; Bhattacharya, A.; Bond, I. A.; Freeman, M.; Hirao, Y.; Itow, Y.; Koshimoto, N.; Li, M. C. A.; Ling, C. H.; Masuda, K.; Fukui, A.; Matsubara, Y.; Muraki, Y.; Nagakane, M.; Nishioka, T.; Ohnishi, K.; Oyokawa, H.; Rattenbury, N. J.; Saito, To.; Sharan, A.; Sullivan, D. J.; Suzuki, D.; Tristram, P. J.; Yonehara, A.; Jorgensen, U. G.; Burgdorf, M. J.; Ciceri, S.; D'Ago, G.; Evans, D. F.; Hinse, T. C.; Kains, N.; Kerins, E.; Korhonen, H.; Mancini, L.; Popovas, A.; Rabus, M.; Rahvar, S.; Scarpetta, G.; Skottfelt, J.; Southworth, J.; Peixinho, N.; Verma, P.; Sbarufatti, B.; Kennea, J. A.; Gehrels, N.
    Simultaneous observations of microlensing events from multiple locations allow for the breaking of degeneracies between the physical properties of the lensing system, specifically by exploring different regions of the lens plane and by directly measuring the "microlens parallax." We report the discovery of a 30-65M(J) brown dwarf orbiting a K dwarf in the microlensing event OGLE-2015-BLG-1319. The system is located at a distance of similar to 5 kpc toward the Galactic Bulge. The event was observed by several ground-based groups as well as by Spitzer and Swift, allowing a measurement of the physical properties. However, the event is still subject to an eight-fold degeneracy, in particular the well-known close-wide degeneracy, and thus the projected separation between the two lens components is either similar to 0.25 au or similar to 45 au. This is the first microlensing event observed by Swift, with the UVOT camera. We study the region of microlensing parameter space to which Swift is sensitive, finding that though Swift could not measure the microlens parallax with respect to ground-based observations for this event, it can be important for other events. Specifically, it is important for detecting nearby brown dwarfs and free-floating planets in high magnification events.