T. Sumi - Department of Earth and Space Science, Osaka University, Japan

T. Sumi
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T. Sumi
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Department of Earth and Space Science, Osaka University, Japan
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Earth and Planetary Astrophysics (41)
 
Solar and Stellar Astrophysics (10)
 
Astrophysics of Galaxies (5)
 
Instrumentation and Methods for Astrophysics (1)
 
Mathematics - Commutative Algebra (1)
 
Cosmology and Nongalactic Astrophysics (1)
 
High Energy Astrophysical Phenomena (1)
 
Mathematics - Rings and Algebras (1)

Publications Authored By T. Sumi

We present a detailed elemental abundance study of 90 F and G dwarf, turn-off and subgiant stars in the Galactic bulge. Based on high-resolution spectra acquired during gravitational microlensing events, stellar ages and abundances for 11 elements (Na, Mg, Al, Si, Ca, Ti, Cr, Fe, Zn, Y and Ba) have been determined. We find that the Galactic bulge has a wide metallicity distribution with significant peaks at [Fe/H]=-1. Read More

It has recently been discovered that some, if not all, classical novae emit GeV gamma-rays during outburst, but the mechanics of this gamma-ray emission are still not well understood. We present here a comprehensive, multi-wavelength dataset---from radio to X-rays---for the most gamma-ray luminous classical nova to-date, V1324 Sco. Using this dataset, we show that V1324 Sco is a canonical dusty Fe-II type nova, with a bulk ejecta velocity of $1150 \pm 40~\rm km~s^{-1}$ and an ejecta mass of $2. Read More

We use the Subaru Hyper Suprime-Cam (HSC) to conduct a high-cadence (2~min sampling) 7~hour long observation of the Andromeda galaxy (M31) to search for the microlensing magnification of stars in M31 due to intervening primordial black holes (PBHs) in the halo regions of the Milky Way (MW) and M31. The combination of an aperture of 8.2m, a field-of-view of 1. Read More

We report the results of the statistical analysis of planetary signals discovered in MOA-II microlensing survey alert system events from 2007 to 2012. We determine the survey sensitivity as a function of planet-star mass ratio, $q$, and projected planet-star separation, $s$, in Einstein radius units. We find that the mass ratio function is not a single power-law, but has a change in slope at $q \sim 10^{-4}$, corresponding to $\sim 20 M_{\oplus}$ for the median host star mass of $\sim 0. Read More

We report the discovery of a planet --- OGLE-2014-BLG-0676Lb --- via gravitational microlensing. Observations for the lensing event were made by the MOA, OGLE, Wise, RoboNET/LCOGT, MiNDSTEp and $\mu$FUN groups. All analyses of the light curve data favour a lens system comprising a planetary mass orbiting a host star. Read More

In the process of analyzing an observed light curve, one often confronts various scenarios that can mimic the planetary signals causing difficulties in the accurate interpretation of the lens system. In this paper, we present the analysis of the microlensing event OGLE-2016-BLG-0733. The light curve of the event shows a long-term asymmetric perturbation that would appear to be due to a planet. Read More

We present the analysis of the first circumbinary planet microlensing event, OGLE-2007-BLG-349. This event has a strong planetary signal that is best fit with a mass ratio of $q \approx 3.4\times10^{-4}$, but there is an additional signal due to an additional lens mass, either another planet or another star. Read More

We report the discovery of a microlensing planet OGLE-2012-BLG-0950Lb with the planet/host mass ratio of $q \sim 2 \times 10^{-4}$. A long term distortion detected in both MOA and OGLE light curve can be explained by the microlens parallax due to the Earth's orbital motion around the Sun. Although the finite source effect is not detected, we obtain the lens flux by the high resolution Keck AO observation. Read More

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 30-55$M_J$ brown dwarf orbiting a K dwarf in microlensing event OGLE-2015-BLG-1319. The system is located at a distance of $\sim$5 kpc toward the Galactic bulge. Read More

We present the first near-infrared scattered-light detection of the transitional disk around V1247 Ori, which was obtained using high-resolution polarimetric differential imaging observations with Subaru/HiCIAO. Our imaging in the H band reveals the disk morphology at separations of ~0.14"-0. Read More

We report the discovery of a planet by the microlensing method, OGLE-2012-BLG-0724Lb. Although the duration of the planetary signal for this event was one of the shortest seen for a planetary event, the anomaly was well covered thanks to high cadence observations taken by the survey groups OGLE and MOA. By analyzing the light curve, this planetary system is found to have a mass ratio $q=(1. Read More

We find that significant incompleteness in stellar number counts results in a significant overestimate of the microlensing optical depth $\tau$ and event rate per star per year $\Gamma$ toward the Galactic bulge from the first two years of the MOA-II survey. We find that the completeness in Red Clump Giant (RCG) counts $f_{\rm RC}$ decreases proportional to the galactic latitude $b$, as $f_{\rm RC}=(0.63\pm0. Read More

Two cold, gas giant planets orbiting a G-type main sequence star in the galactic disk have previously been discovered in the high magnification microlensing event OGLE-2012-BLG-0026 (Han et al. 2013). Here we present revised host star flux measurements and a refined model for the two-planet system using additional light curve data. Read More

Spitzer microlensing parallax observations of OGLE-2015-BLG-1212 decisively breaks a degeneracy between planetary and binary solutions that is somewhat ambiguous when only ground-based data are considered. Only eight viable models survive out of an initial set of 32 local minima in the parameter space. These models clearly indicate that the lens is a stellar binary system possibly located within the bulge of our Galaxy, ruling out the planetary alternative. Read More

2015Dec
Authors: Calen B. Henderson, Radosław Poleski, Matthew Penny, Rachel A. Street, David P. Bennett, David W. Hogg, B. Scott Gaudi, W. Zhu, T. Barclay, G. Barentsen, S. B. Howell, F. Mullally, A. Udalski, M. K. Szymański, J. Skowron, P. Mróz, S. Kozłowski, Ł. Wyrzykowski, P. Pietrukowicz, I. Soszyński, K. Ulaczyk, M. Pawlak, T. Sumi, F. Abe, Y. Asakura, R. K. Barry, A. Bhattacharya, I. A. Bond, M. Donachie, M. Freeman, A. Fukui, Y. Hirao, Y. Itow, N. Koshimoto, M. C. A. Li, C. H. Ling, K. Masuda, Y. Matsubara, Y. Muraki, M. Nagakane, K. Ohnishi, H. Oyokawa, N. Rattenbury, To. Saito, A. Sharan, D. J. Sullivan, P. J. Tristram, A. Yonehara, E. Bachelet, D. M. Bramich, A. Cassan, M. Dominik, R. Figuera Jaimes, K. Horne, M. Hundertmark, S. Mao, C. Ranc, R. Schmidt, C. Snodgrass, I. A. Steele, Y. Tsapras, J. Wambsganss, V. Bozza, M. J. Burgdorf, U. G. Jørgensen, S. Calchi Novati, S. Ciceri, G. D'Ago, D. F. Evans, F. V. Hessman, T. C. Hinse, T. -O. Husser, L. Mancini, A. Popovas, M. Rabus, S. Rahvar, G. Scarpetta, J. Skottfelt, J. Southworth, E. Unda-Sanzana, S. T. Bryson, D. A. Caldwell, M. R. Haas, K. Larson, K. McCalmont, M. Packard, C. Peterson, D. Putnam, L. Reedy, S. Ross, J. E. Van Cleve, R. Akeson, V. Batista, J. -P. Beaulieu, C. A. Beichman, G. Bryden, D. Ciardi, A. Cole, C. Coutures, D. Foreman-Mackey, P. Fouqué, M. Friedmann, C. Gelino, S. Kaspi, E. Kerins, H. Korhonen, D. Lang, C. -H. Lee, C. H. Lineweaver, D. Maoz, J. -B. Marquette, F. Mogavero, J. C. Morales, D. Nataf, R. W. Pogge, A. Santerne, Y. Shvartzvald, D. Suzuki, M. Tamura, P. Tisserand, D. Wang

$K2$'s Campaign 9 ($K2$C9) will conduct a $\sim$3.7 deg$^{2}$ survey toward the Galactic bulge from 7/April through 1/July of 2016 that will leverage the spatial separation between $K2$ and the Earth to facilitate measurement of the microlens parallax $\pi_{\rm E}$ for $\gtrsim$127 microlensing events. These will include several that are planetary in nature as well as many short-timescale microlensing events, which are potentially indicative of free-floating planets (FFPs). Read More

Let $m,n\geq 3$, $(m-1)(n-1)+2\leq p\leq mn$, and $u=mn-p$. The set $\mathbb{R}^{u\times n\times m}$ of all real tensors with size $u\times n\times m$ is one to one corresponding to the set of bilinear maps $\mathbb{R}^m\times \mathbb{R}^n\to \mathbb{R}^u$. We show that $\mathbb{R}^{m\times n\times p}$ has plural typical ranks $p$ and $p+1$ if and only if there exists a nonsingular bilinear map $\mathbb{R}^m\times\mathbb{R}^n\to\mathbb{R}^{u}$. Read More

2015Dec
Affiliations: 1The OGLE Collaboration, 2The OGLE Collaboration, 3The OGLE Collaboration, 4The OGLE Collaboration, 5The OGLE Collaboration, 6The OGLE Collaboration, 7The OGLE Collaboration, 8The OGLE Collaboration, 9The OGLE Collaboration, 10The OGLE Collaboration, 11The MOA Collaboration, 12The MOA Collaboration, 13The MOA Collaboration, 14The MOA Collaboration, 15The MOA Collaboration, 16The MOA Collaboration, 17The MOA Collaboration, 18The MOA Collaboration, 19The MOA Collaboration, 20The MOA Collaboration, 21The MOA Collaboration, 22The MOA Collaboration, 23The MOA Collaboration, 24The MOA Collaboration, 25The MOA Collaboration, 26The MOA Collaboration, 27The MOA Collaboration, 28The MOA Collaboration, 29The MOA Collaboration, 30The MOA Collaboration, 31The MOA Collaboration, 32The MOA Collaboration, 33The MiNDSTEp Collaboration, 34The MiNDSTEp Collaboration, 35The MiNDSTEp Collaboration, 36The MiNDSTEp Collaboration, 37The MiNDSTEp Collaboration, 38The MiNDSTEp Collaboration

We present the discovery of a Neptune-mass planet orbiting a 0.8 +- 0.3 M_Sun star in the Galactic bulge. Read More

2015Nov
Affiliations: 1The MOA Collaboration, 2The MOA Collaboration, 3The MOA Collaboration, 4The MOA Collaboration, 5The MOA Collaboration, 6The MOA Collaboration, 7The MOA Collaboration, 8The MOA Collaboration, 9The MOA Collaboration, 10The MOA Collaboration, 11The MOA Collaboration, 12The MOA Collaboration, 13The MOA Collaboration, 14The MOA Collaboration, 15The MOA Collaboration, 16The MOA Collaboration, 17The MOA Collaboration, 18The MOA Collaboration, 19The MOA Collaboration, 20The MOA Collaboration, 21The MOA Collaboration, 22The MOA Collaboration, 23The MOA Collaboration, 24The MOA Collaboration, 25The MOA Collaboration, 26The MOA Collaboration, 27The MOA Collaboration, 28The MOA Collaboration, 29The MOA Collaboration, 30The MOA Collaboration, 31The MOA Collaboration, 32The MOA Collaboration, 33The MOA Collaboration, 34The MOA Collaboration, 35The MOA Collaboration, 36The MOA Collaboration, 37The MOA Collaboration

We present the discovery of the first Neptune analog exoplanet or super-Earth with Neptune-like orbit, MOA-2013-BLG-605Lb. This planet has a mass similar to that of Neptune or a super-Earth and it orbits at $9\sim 14$ times the expected position of the snow-line, $a_{\rm snow}$, which is similar to Neptune's separation of $ 11\,a_{\rm snow}$ from the Sun. The planet/host-star mass ratio is $q=(3. Read More

We propose a new concept for spectral characterization of transiting exoplanets with future space-based telescopes. This concept, called as densified pupil spectroscopy, allows us to perform high, stable spectrophotometry against telescope pointing jitter and deformation of the primary mirror. This densified pupil spectrometer comprises the following three roles: division of a pupil into a number of sub-pupils, densification of each sub-pupil, and acquisition of the spectrum of each sub-pupil with a conventional spectrometer. Read More

We present a statistical analysis of the first four seasons from a "second-generation" microlensing survey for extrasolar planets, consisting of near-continuous time coverage of 8 deg$^2$ of the Galactic bulge by the OGLE, MOA, and Wise microlensing surveys. During this period, 224 microlensing events were observed by all three groups. Over 12% of the events showed a deviation from single-lens microlensing, and for $\sim$1/3 of those the anomaly is likely caused by a planetary companion. Read More

For all exoplanet candidates, the reliability of a claimed detection needs to be assessed through a careful study of systematic errors in the data to minimize the false positives rate. We present a method to investigate such systematics in microlensing datasets using the microlensing event OGLE-2013-BLG-0446 as a case study. The event was observed from multiple sites around the world and its high magnification (A_{max} \sim 3000) allowed us to investigate the effects of terrestrial and annual parallax. Read More

We report the discovery of a possible planet in microlensing event MOA-2010-BLG-353. This event was only recognised as having a planetary signal after the microlensing event had finished, and following a systematic analysis of all archival data for binary lens microlensing events collected to date. Data for event MOA-2010-BLG-353 were only recorded by the high cadence observations of the OGLE and MOA survey groups. Read More

2015Aug

We report the detection of a Cold Neptune m_planet=21+/-2MEarth orbiting a 0.38MSol M dwarf lying 2.5-3. Read More

The presence of excess emission at 3.6--8.0 $\mu$m was investigated in a sample of 27 binary systems located in two nearby star-forming regions, Taurus and Ophiuchus, by using Spitzer/Infrared Array Camera (IRAC) archival data. Read More

To move one step forward toward a Galactic distribution of planets, we present the first planet sensitivity analysis for microlensing events with simultaneous observations from space and the ground. We present this analysis for two such events, OGLE-2014-BLG-0939 and OGLE-2014-BLG-0124, which both show substantial planet sensitivity even though neither of them reached high magnification. This suggests that an ensemble of low to moderate magnification events can also yield significant planet sensitivity and therefore probability to detect planets. Read More

We report the discovery of a microlensing exoplanet OGLE-2012-BLG-0563Lb with the planet-star mass ratio ~1 x 10^{-3}. Intensive photometric observations of a high-magnification microlensing event allow us to detect a clear signal of the planet. Although no parallax signal is detected in the light curve, we instead succeed at detecting the flux from the host star in high-resolution JHK'-band images obtained by the Subaru/AO188 and IRCS instruments, allowing us to constrain the absolute physical parameters of the planetary system. Read More

2015May
Affiliations: 1Sorbonne Universités, UPMC Univ Paris 6 et CNRS, UMR 7095, Institut d'Astrophysique de Paris, 2Sorbonne Universités, UPMC Univ Paris 6 et CNRS, UMR 7095, Institut d'Astrophysique de Paris, 3University of Canterbury, Dept. of Physics and Astronomy, New Zealand, 4Sorbonne Universités, UPMC Univ Paris 6 et CNRS, UMR 7095, Institut d'Astrophysique de Paris, 5Institute of Natural and Mathematical Sciences, Massey University, Auckland, New Zealand, 6Sorbonne Universités, UPMC Univ Paris 6 et CNRS, UMR 7095, Institut d'Astrophysique de Paris, 7Sorbonne Universités, UPMC Univ Paris 6 et CNRS, UMR 7095, Institut d'Astrophysique de Paris, 8Department of Physics, University of Notre Dame, 9SUPA, School of Physics & Astronomy, North Haugh, University of St Andrews, 10Kavli Institute for Astronomy and Astrophysics, Peking University, 11IRAP, CNRS - Université de Toulouse, 12Department of Astronomy, Ohio State University, 13School of Math and Physics, University of Tasmania, Australia, 14Niels Bohr Institutet, Københavns Universitet, Denmark, 15Space Telescope Science Institute, Baltimore, MD, 16South African Astronomical Observatory, South Africa, 17Department of Earth and Space Science, Osaka University, Japan, 18Qatar Environment and Energy Research Institute, Qatar Foundation, 19Sorbonne Universités, UPMC Univ Paris 6 et CNRS, UMR 7095, Institut d'Astrophysique de Paris, 20Sorbonne Universités, UPMC Univ Paris 6 et CNRS, UMR 7095, Institut d'Astrophysique de Paris, 21Department of Physics, University of Rijeka, Croatia, 22Technical University of Vienna, Department of Computing, 23Department of Astronomy, Ohio State University, 24Department of Physics, Chungbuk National University, Korea, 25SUPA, School of Physics & Astronomy, North Haugh, University of St Andrews, 26SUPA, School of Physics & Astronomy, North Haugh, University of St Andrews, 27Department of Physics and Astronomy, San Francisco State University, 28Korea Astronomy and Space Science Institute, Daejeon, Korea, 29Sorbonne Universités, UPMC Univ Paris 6 et CNRS, UMR 7095, Institut d'Astrophysique de Paris, 30Korea Astronomy and Space Science Institute, Daejeon, Korea, 31University of Canterbury, Dept. of Physics and Astronomy, New Zealand, 32Space Telescope Science Institute, Baltimore, MD, 33Las Cumbres Observatory Global Telescope Network, Goleta, CA, 34Las Cumbres Observatory Global Telescope Network, Goleta, CA, 35Astronomisches Rechen-Institut, Zentrum für Astronomie der Universität Heidelberg, 36Perth Observatory, Walnut Road, Bickley, Perth 6076, Australia, 37Astronomisches Rechen-Institut, Zentrum für Astronomie der Universität Heidelberg, 38Solar-Terrestrial Environment Laboratory, Nagoya University, Japan, 39Okayama Astrophysical Observatory, National Astronomical Observatory of Japan, 40Solar-Terrestrial Environment Laboratory, Nagoya University, Japan, 41Solar-Terrestrial Environment Laboratory, Nagoya University, Japan, 42Solar-Terrestrial Environment Laboratory, Nagoya University, Japan, 43Solar-Terrestrial Environment Laboratory, Nagoya University, Japan, 44Nagano National College of Technology, Japan, 45Department of Physics, University of Auckland, New Zealand, 46Tokyo Metropolitan College of Aeronautics, Japan, 47School of Chemical and Physical Sciences, Victoria University, Wellington, New Zealand, 48Institute of Information and Mathematical Sciences, Massey University at Albany, Auckland, New Zealand, 49Mt. John University Observatory, Lake Tekapo, New Zealand, 50Department of Physics, University of Auckland, New Zealand, 51Department of Physics, Faculty of Science, Kyoto Sangyo University, Japan

We present the analysis of MOA-2007-BLG-197Lb, the first brown dwarf companion to a Sun-like star detected through gravitational microlensing. The event was alerted and followed-up photometrically by a network of telescopes from the PLANET, MOA, and uFUN collaborations, and observed at high angular resolution using the NaCo instrument at the VLT. From the modelling of the microlensing light curve, we derived the binary lens separation in Einstein radius units (s~1. Read More

We reanalyze microlensing events in the published list of anomalous events that were observed from the OGLE lensing survey conducted during 2004-2008 period. In order to check the existence of possible degenerate solutions and extract extra information, we conduct analyses based on combined data from other survey and follow-up observation and consider higher-order effects. Among the analyzed events, we present analyses of 8 events for which either new solutions are identified or additional information is obtained. Read More

We present a Subaru/IRCS H-band image of the edge-on debris disk around the F2V star HD 15115. We detected the debris disk, which has a bow shape and an asymmetric surface brightness, at a projected separation of 1--3" (~50--150 AU). The disk surface brightness is ~0. Read More

Recently Sumi et al. (2011) reported evidence for a large population of planetary-mass objects (PMOs) that are either unbound or orbit host stars in orbits > 10 AU. Their result was deduced from the statistical distribution of durations of gravitational microlensing events observed by the MOA collaboration during 2006 and 2007. Read More

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 ~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. Read More

2014Oct
Authors: J. Skowron, I. -G. Shin, A. Udalski, C. Han, T. Sumi, Y. Shvartzvald, A. Gould, D. Dominis-Prester, R. A. Street, U. G. Jørgensen, D. P. Bennett, V. Bozza, M. K. Szymański, M. Kubiak, G. Pietrzyński, I. Soszyński, R. Poleski, S. Kozłowski, P. Pietrukowicz, K. Ulaczyk, Ł. Wyrzykowski, F. Abe, A. Bhattacharya, I. A. Bond, C. S. Botzler, M. Freeman, A. Fukui, D. Fukunaga, Y. Itow, C. H. Ling, N. Koshimoto, K. Masuda, Y. Matsubara, Y. Muraki, S. Namba, K. Ohnishi, L. C. Philpott, N. Rattenbury, T. Saito, D. J. Sullivan, D. Suzuki, P. J. Tristram, P. C. M. Yock, D. Maoz, S. Kaspi, M. Friedman, L. A. Almeida, V. Batista, G. Christie, J. -Y. Choi, D. L. DePoy, B. S. Gaudi, C. Henderson, K. -H. Hwang, F. Jablonski, Y. K. Jung, C. -U. Lee, J. McCormick, T. Natusch, H. Ngan, H. Park, R. W. Pogge, J. Yee, M. D. Albrow, E. Bachelet, J. -P. Beaulieu, S. Brillant, J. A. R. Caldwell, A. Cassan, A. Cole, E. Corrales, Ch. Coutures, S. Dieters, J. Donatowicz, P. Fouqué, J. Greenhill, N. Kains, S. R. Kane, D. Kubas, J. -B. Marquette, R. Martin, J. Menzies, K. R. Pollard, C. Ranc, K. C. Sahu, J. Wambsganss, A. Williams, D. Wouters, Y. Tsapras, D. M. Bramich, K. Horne, M. Hundertmark, C. Snodgrass, I. A. Steele, K. A. Alsubai, P. Browne, M. J. Burgdorf, S. Calchi Novati, P. Dodds, M. Dominik, S. Dreizler, X. -S. Fang, C. -H. Gu, Hardis, K. Harpsøe, F. V. Hessman, T. C. Hinse, A. Hornstrup, J. Jessen-Hansen, E. Kerins, C. Liebig, M. Lund, M. Lundkvist, L. Mancini, M. Mathiasen, M. T. Penny, S. Rahvar, D. Ricci, G. Scarpetta, J. Skottfelt, J. Southworth, J. Surdej, J. Tregloan-Reed, O. Wertz

We report the discovery of a Jupiter-mass planet orbiting an M-dwarf star that gave rise to the microlensing event OGLE-2011-BLG-0265. Such a system is very rare among known planetary systems and thus the discovery is important for theoretical studies of planetary formation and evolution. High-cadence temporal coverage of the planetary signal combined with extended observations throughout the event allows us to accurately model the observed light curve. Read More

We compared the number of faint stars detected in deep survey fields with the current stellar distribution model of the Galaxy and found that the detected number in the H band is significantly smaller than the predicted number. This indicates that M-dwarfs, the major component, are fewer in the halo and the thick disk. We used archived data of several surveys in both the north and south field of GOODS (Great Observatories Origins Deep Survey), MODS in GOODS-N, and ERS and CANDELS in GOODS-S. Read More

NASA's proposed WFIRST-AFTA mission will discover thousands of exoplanets with separations from the habitable zone out to unbound planets, using the technique of gravitational microlensing. The Study Analysis Group 11 of the NASA Exoplanet Program Analysis Group was convened to explore scientific programs that can be undertaken now, and in the years leading up to WFIRST's launch, in order to maximize the mission's scientific return and to reduce technical and scientific risk. This report presents those findings, which include suggested precursor Hubble Space Telescope observations, a ground-based, NIR microlensing survey, and other programs to develop and deepen community scientific expertise prior to the mission. Read More

We investigated the magnitude-phase relation of (162173) 1999 JU3, a target asteroid for the JAXA Hayabusa 2 sample return mission. We initially employed the international Astronomical Union's H-G formalism but found that it fits less well using a single set of parameters. To improve the inadequate fit, we employed two photometric functions, the Shevchenko and Hapke functions. Read More

The mass of the lenses giving rise to Galactic microlensing events can be constrained by measuring the relative lens-source proper motion and lens flux. The flux of the lens can be separated from that of the source, companions to the source, and unrelated nearby stars with high-resolution images taken when the lens and source are spatially resolved. For typical ground-based adaptive optics (AO) or space-based observations, this requires either inordinately long time baselines or high relative proper motions. Read More

Characterizing a microlensing planet is done from modeling an observed lensing light curve. In this process, it is often confronted that solutions of different lensing parameters result in similar light curves, causing difficulties in uniquely interpreting the lens system, and thus understanding the causes of different types of degeneracy is important. In this work, we show that incomplete coverage of a planetary perturbation can result in degenerate solutions even for events where the planetary signal is detected with a high level of statistical significance. Read More

We present the first microlensing candidate for a free-floating exoplanet-exomoon system, MOA-2011-BLG-262, with a primary lens mass of M_host ~ 4 Jupiter masses hosting a sub-Earth mass moon. The data are well fit by this exomoon model, but an alternate star+planet model fits the data almost as well. Nevertheless, these results indicate the potential of microlensing to detect exomoons, albeit ones that are different from the giant planet moons in our solar system. Read More

We report analysis of high microlensing event MOA-2008-BLG-379, which has a strong microlensing anomaly at its peak, due to a massive planet with a mass ratio of q = 6.9 x 10^{-3}. Because the faint source star crosses the large resonant caustic, the planetary signal dominates the light curve. Read More

We used Keck adaptive optics observations to identify the first planet discovered by microlensing to lie in or near the habitable zone, i.e., at projected separation $r_\perp=1. Read More

2013Oct
Authors: Y. Tsapras, J. -Y. Choi, R. A. Street, C. Han, V. Bozza, A. Gould, M. Dominik, J. -P. Beaulieu, A. Udalski, U. G. Jørgensen, T. Sumi, D. M. Bramich, P. Browne, K. Horne, M. Hundertmark, S. Ipatov, N. Kains, C. Snodgrass, I. A. Steele, K. A. Alsubai, J. M. Andersen, S. Calchi Novati, Y. Damerdji, C. Diehl, A. Elyiv, E. Giannini, S. Hardis, K. Harpsøe, T. C. Hinse, D. Juncher, E. Kerins, H. Korhonen, C. Liebig, L. Mancini, M. Mathiasen, M. T. Penny, M. Rabus, S. Rahvar, G. Scarpetta, J. Skottfelt, J. Southworth, J. Surdej, J. Tregloan-Reed, C. Vilela, J. Wambsganss, J. Skowron, R. Poleski, S. Kozłowski, Łukasz Wyrzykowski, M. K. Szymański, M. Kubiak, P. Pietrukowicz, G. Pietrzyński, I. Soszyński, K. Ulaczyk, M. D. Albrow, E. Bachelet, R. Barry, V. Batista, A. Bhattacharya, S. Brillant, J. A. R. Caldwell, A. Cassan, A. Cole, E. Corrales, Ch. Coutures, S. Dieters, D. Dominis Prester, J. Donatowicz, P. Fouqué, J. Greenhill, S. R. Kane, D. Kubas, J. -B. Marquette, J. Menzies, C. P`ere, K. R. Pollard, D. Wouters, G. Christie, D. L. DePoy, S. Dong, J. Drummond, B. S. Gaudi, C. B. Henderson, K. H. Hwang, Y. K. Jung, A. Kavka, J. -R. Koo, C. -U. Lee, D. Maoz, L. A. G. Monard, T. Natusch, H. Ngan, H. Park, R. W. Pogge, I. Porritt, I. -G. Shin, Y. Shvartzvald, T. G. Tan, J. C. Yee, F. Abe, D. P. Bennett, I. A. Bond, C. S. Botzler, M. Freeman, A. Fukui, D. Fukunaga, Y. Itow, N. Koshimoto, C. H. Ling, K. Masuda, Y. Matsubara, Y. Muraki, S. Namba, K. Ohnishi, N. J. Rattenbury, To. Saito, D. J. Sullivan, W. L. Sweatman, D. Suzuki, P. J. Tristram, N. Tsurumi, K. Wada, N. Yamai, P. C. M. Yock A. Yonehara

We present a detailed analysis of survey and follow-up observations of microlensing event OGLE-2012-BLG-0406 based on data obtained from 10 different observatories. Intensive coverage of the lightcurve, especially the perturbation part, allowed us to accurately measure the parallax effect and lens orbital motion. Combining our measurement of the lens parallax with the angular Einstein radius determined from finite-source effects, we estimate the physical parameters of the lens system. Read More

Global "second-generation" microlensing surveys aim to discover and characterize extrasolar planets and their frequency, by means of round-the-clock high-cadence monitoring of a large area of the Galactic bulge, in a controlled experiment. We report the discovery of a giant planet in microlensing event MOA-2011-BLG-322. This moderate-magnification event, which displays a clear anomaly induced by a second lensing mass, was inside the footprint of our second-generation microlensing survey, involving MOA, OGLE and the Wise Observatory. Read More

2013Sep
Authors: K. Furusawa, A. Udalski, T. Sumi, D. P. Bennett, I. A. Bond, A. Gould, U. G. Jorgensen, C. Snodgrass, D. Dominis Prester, M. D. Albrow, F. Abe, C. S. Botzler, P. Chote, M. Freeman, A. Fukui, P. Harris, Y. Itow, C. H. Ling, K. Masuda, Y. Matsubara, N. Miyake, Y. Muraki, K. Ohnishi, N. J. Rattenbury, To. Saito, D. J. Sullivan, D. Suzuki, W. L. Sweatman, P. J. Tristram, K. Wada, P. C. M. Yock, M. K. Szymanski, I. Soszynski, M. Kubiak, R. Poleski, K. Ulaczyk, G. Pietrzynski, L. Wyrzykowski, J. Y. Choi, G. W. Christie, D. L. DePoy, S. Dong, J. Drummond, B. S. Gaudi, C. Han, L. -W. Hung, Y. -K. Jung, C. -U. Lee, J. McCormick, D. Moorhouse, T. Natusch, M. Nola, E. Ofek, B. G. Park, H. Park, R. W. Pogge, I. -G. Shin, J. Skowron, G. Thornley, J. C. Yee, K. A. Alsubai, V. Bozza, P. Browne, M. J. Burgdorf, S. Calchi Novati, P. Dodds, M. Dominik, F. Finet, T. Gerner, S. Hardis, K. Harpsoe, T. C. Hinse, M. Hundertmark, N. Kains, E. Kerins, C. Liebig, L. Mancini, M. Mathiasen, M. T. Penny, S. Proft, S. Rahvar, D. Ricci, G. Scarpetta, S. Schafer, F. Schonebeck, J. Southworth, J. Surdej, J. Wambsganss, R. A. Street, D. M. Bramich, I. A. Steele, Y. Tsapras, K. Horne, J. Donatowicz, K. C. Sahu, E. Bachelet, V. Batista, T. G. Beatty, J. -P. Beaulieu, C. S. Bennett, C. Black, R. Bowens-Rubin, S. Brillant, J. A. R. Caldwell, A. Cassan, A. A. Cole, E. Corrales, C. Coutures, S. Dieters, P. Fouque, J. Greenhill, C. B. Henderson, D. Kubas, J. -B. Marquette, R. Martin, J. W. Menzies, B. Shappee, A. Williams, D. Wouters, J. van Saders, R. Zellem, M. Zub

We analyze the planetary microlensing event MOA-2010-BLG-328. The best fit yields host and planetary masses of Mh = 0.11+/-0. Read More

A planetary microlensing signal is generally characterized by a short-term perturbation to the standard single lensing light curve. A subset of binary-source events can produce perturbations that mimic planetary signals, thereby introducing an ambiguity between the planetary and binary-source interpretations. In this paper, we present analysis of the microlensing event MOA-2012-BLG-486, for which the light curve exhibits a short-lived perturbation. Read More