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1. Discovery of a Jupiter/Saturn Analog with Gravitational Microlensing

Author

Gaudi, B. S., Bennett, D. P., Udalski, A., Gould, A., Christie, G. W., Maoz, D., Dong, S., McCormick, J., Szymański, M. K., Tristram, P. J., Nikolaev, S., Paczyński, B., Kubiak, M., Pietrzyński, G., Soszyński, I., Szewczyk, O., Ulaczyk, K., Wyrzykowski, Ł., DePoy, D. L., Han, C., Kaspi, S., Lee, C.-U., Mallia, F., Natusch, T., Pogge, R. W., Park, B.-G., Abe, F., Bond, I. A., Botzler, C. S., Fukui, A., Hearnshaw, J. B., Itow, Y., Kamiya, K., Korpela, A. V., Kilmartin, P. M., Lin, W., Masuda, K., Matsubara, Y., Motomura, M., Muraki, Y., Nakamura, S., Okumura, T., Ohnishi, K., Rattenbury, N. J., Sako, T., Saito, To., Sato, S., Skuljan, L., Sullivan, D. J., Sumi, T., Sweatman, W. L., Yock, P. C. M., Albrow, M. D., Allan, A., Beaulieu, J.-P., Burgdorf, M. J., Cook, K. H., Coutures, C., Dominik, M., Dieters, S., Fouqué, P., Greenhill, J., Horne, K., Steele, I., Tsapras, Y., Chaboyer, B., Crocker, A., Frank, S., and Macintosh, B.

Published
2008
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2. OGLE-2017-BLG-0406: Spitzer Microlens Parallax Reveals Saturn-mass Planet Orbiting M-dwarf Host in the Inner Galactic Disk

Author

Hirao, Y, Bennett, DP, Ryu, Y-H, Koshimoto, N, Udalski, A, Yee, JC, Sumi, T, Bond, IA, Shvartzvald, Y, Abe, F, Barry, RK, Bhattacharya, A, Donachie, M, Fukui, A, Itow, Y, Kondo, I, Li, MCA, Matsubara, Y, Matsuo, T, Miyazaki, S, Muraki, Y, Nagakane, M, Ranc, C, Rattenbury, NJ, Suematsu, H, Shibai, H, Suzuki, D, Tristram, PJ, Yonehara, A, Skowron, J, Poleski, R, Mroz, P, Szymanski, MK, Soszynski, I, Kozlowski, S, Pietrukowicz, P, Ulaczyk, K, Rybicki, K, Iwanek, P, Albrow, MD, Chung, S-J, Gould, A, Han, C, Hwang, K-H, Jung, YK, Shin, I-G, Zang, W, Cha, S-M, Kim, D-J, Kim, H-W, Kim, S-L, Lee, C-U, Lee, D-J, Lee, Y, Park, B-G, Pogge, RW, Beichman, CA, Bryden, G, Novati, SC, Carey, S, Gaudi, BS, Henderson, CB, Zhu, W, Bachelet, E, Bolt, G, Christie, G, Hundertmark, M, Natusch, T, Maoz, D, McCormick, J, Street, RA, Tan, T-G, Tsapras, Y, Jorgensen, UG, Dominik, M, Bozza, V, Skottfelt, J, Snodgrass, C, Ciceri, S, Jaimes, RF, Evans, DF, Peixinho, N, Hinse, TC, Burgdorf, MJ, Southworth, J, Rahvar, S, Sajadian, S, Rabus, M, von Essen, C, Fujii, YI, Campbell-White, J, Lowry, S, Helling, C, Mancini, L, Haikala, L, Kandori, R, Collaboration, MOA, Collaboration, OGLE, Collaboration, K, Team, S, Teams, LCOFF-U, Collaboration, M, Team, IRSF, University of St Andrews. School of Physics and Astronomy, and University of St Andrews. St Andrews Centre for Exoplanet Science

Subjects
010504 meteorology & atmospheric sciences, GRAVITATIONAL LENSING EXPERIMENT, Astrophysics, 01 natural sciences, JUPITER/SATURN ANALOG, Bulge, Planet, Saturn, QB Astronomy, 010303 astronomy & astrophysics, QC, QB, Earth and Planetary Astrophysics (astro-ph.EP), Physics, education.field_of_study, Settore FIS/05, LUMINOSITY-RELATION, INTERSTELLAR EXTINCTION LAW, Astrophysics - Solar and Stellar Astrophysics, MILKY-WAY, Astrophysics::Earth and Planetary Astrophysics, Proper motion, astro-ph.SR, astro-ph.GA, Population, NDAS, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, Gravitational microlensing, Gravitational microlensing exoplanet detection, EVENTS, SYSTEMS, 0103 physical sciences, PHOTOMETRY, DETERMINISTIC MODEL, education, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences, Astronomy and Astrophysics, Mass ratio, Light curve, Astrophysics - Astrophysics of Galaxies, QC Physics, 13. Climate action, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), astro-ph.EP, STARS, Astrophysics - Earth and Planetary Astrophysics
Abstract

We report the discovery and analysis of the planetary microlensing event OGLE-2017-BLG-0406, which was observed both from the ground and by the ${\it Spitzer}$ satellite in a solar orbit. At high magnification, the anomaly in the light curve was densely observed by ground-based-survey and follow-up groups, and it was found to be explained by a planetary lens with a planet/host mass ratio of $q=7.0 \times 10^{-4}$ from the light-curve modeling. The ground-only and ${\it Spitzer}$-"only" data each provide very strong one-dimensional (1-D) constraints on the 2-D microlens parallax vector $\bf{\pi_{\rm E}}$. When combined, these yield a precise measurement of $\bf{\pi_{\rm E}}$, and so of the masses of the host $M_{\rm host}=0.56\pm0.07\,M_\odot$ and planet $M_{\rm planet} = 0.41 \pm 0.05\,M_{\rm Jup}$. The system lies at a distance $D_{\rm L}=5.2 \pm 0.5 \ {\rm kpc}$ from the Sun toward the Galactic bulge, and the host is more likely to be a disk population star according to the kinematics of the lens. The projected separation of the planet from the host is $a_{\perp} = 3.5 \pm 0.3 \ {\rm au}$, i.e., just over twice the snow line. The Galactic-disk kinematics are established in part from a precise measurement of the source proper motion based on OGLE-IV data. By contrast, the ${\it Gaia}$ proper-motion measurement of the source suffers from a catastrophic $10\,\sigma$ error., Comment: 40 pages, 12 figures, 10 tables, accepted for publication in The Astronomical Journal

Published
2020

3. OGLE-2017-BLG-0039: Microlensing Event with Light from a Lens Identified from Mass Measurement

Author

Han, C., Jung, Y. K., Udalski, A., Bond, I., Bozza, V., The, KMTNet Collaboration, Albrow, M. D., Chung, S.-J., Gould, A., Hwang, K.-H., Kim, D., Lee, C.-U., Kim, H.-W., Ryu, Y.-H., Shin, I.-G., Yee, J. C., Shvartzvald, Y., Cha, S.-M., Kim, S.-L., Kim, D.-J., Lee, D.-J., Lee, Y., Park, B.-G., Pogge, R. W., The, OGLE Collaboration Szymański M. K., Mróz, P., Skowron, J., Poleski, R., Soszyński, I., Kozłowski, S., Pietrukowicz, P., Ulaczyk, K., Pawlak, M., The, MOA Collaboration Abe F., Barry, R., 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., Matsubara, Y., Miyazaki, S., Munakata, H., Muraki, Y., Nagakane, M., Ohnishi, K., Ranc, C., Rattenbury, N., Saito, T., Sharan, A., Sullivan, D. J., Sumi, T., Suzuki, Daisuke, Tristram, P. J., Yamada, T., and Yonehara, A.

Subjects
Brightness, 010504 meteorology & atmospheric sciences, Event (relativity), FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, gravitational lensing: micro, Gravitational microlensing, 01 natural sciences, Einstein radius, law.invention, law, 0103 physical sciences, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), 0105 earth and related environmental sciences, Physics, Astronomy and Astrophysics, binaries: general, Space and Planetary Science, Lens (optics), Stars, Astrophysics - Solar and Stellar Astrophysics, Caustic (optics), Astrophysics::Earth and Planetary Astrophysics, Parallax
Abstract

著者人数: 61名（所属. 宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS): 鈴木, 大介), Accepted: 2018-09-27, 資料番号: SA1180205000

Published
2018

4. Toward a Galactic Distribution of Planets. I. Methodology and Planet Sensitivities of the 2015 High-cadence Spitzer Microlens Sample

Author

Zhu, Wei, Udalski, A., Novati, S. Calchi, Chung, S. -J., Jung, Y. K., Ryu, Y. -H., Shin, I. -G., Gould, A., Lee, C. -U., Albrow, M. D., Yee, J. C., Han, C., Hwang, K. -H., Cha, S. -M., Kim, D. -J., Kim, H. -W., Kim, S. -L., Kim, Y. -H., Lee, Y., Park, B. -G., Pogge, R., Poleski, R., Skowron, J., Mroz, P., Szymanski, M. K., Soszynski, I., Pietrukowicz, P., Kozlowski, S., Ulaczyk, K., Pawlak, M., Beichman, C., Bryden, G., Carey, S., Fausnaugh, M., Gaudi, B. S., Henderson, C., Shvartzvald, Y., and Wibking, B.

Subjects
Physics, 010308 nuclear & particles physics, Astrophysics::Instrumentation and Methods for Astrophysics, Astronomy and Astrophysics, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Planetary system, Mass ratio, Gravitational microlensing, 01 natural sciences, Stars, Space and Planetary Science, Bulge, Planet, 0103 physical sciences, Range (statistics), Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Parallax, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Astrophysics - Earth and Planetary Astrophysics
Abstract

We analyze an ensemble of microlensing events from the 2015 Spitzer microlensing campaign, all of which were densely monitored by ground-based high-cadence survey teams. The simultaneous observations from Spitzer and the ground yield measurements of the microlensing parallax vector $\pi_{\rm E}$, from which compact constraints on the microlens properties are derived, including $\lesssim$25\% uncertainties on the lens mass and distance. With the current sample, we demonstrate that the majority of microlenses are indeed in the mass range of M dwarfs. The planet sensitivities of all 41 events in the sample are calculated, from which we provide constraints on the planet distribution function. In particular, assuming a planet distribution function that is uniform in $\log{q}$, where $q$ is the planet-to-star mass ratio, we find a $95\%$ upper limit on the fraction of stars that host typical microlensing planets of 49\%, which is consistent with previous studies. Based on this planet-free sample, we develop the methodology to statistically study the Galactic distribution of planets using microlensing parallax measurements. Under the assumption that the planet distributions are the same in the bulge as in the disk, we predict that $\sim$1/3 of all planet detections from the microlensing campaigns with Spitzer should be in the bulge. This prediction will be tested with a much larger sample, and deviations from it can be used to constrain the abundance of planets in the bulge relative to the disk., Comment: published on Astronomical Journal

Published
2017

5. MASS MEASUREMENTS of ISOLATED OBJECTS from SPACE-BASED MICROLENSING

Author

Zhu, W, Novati, SC, Gould, A, Udalski, A, Han, C, Shvartzvald, Y, Ranc, C, Jorgensen, UG, Poleski, R, Bozza, V, Beichman, C, Bryden, G, Carey, S, Gaudi, BS, Henderson, CB, Pogge, RW, Porritt, I, Wibking, B, Yee, JC, Pawlak, M, Szymanski, MK, Skowron, J, Mroz, P, Kozlowski, S, Wyrzykowski, L, Pietrukowicz, P, Pietrzynski, G, Soszynski, I, Ulaczyk, K, Choi, J-Y, Park, H, Jung, YK, Shin, I-G, Albrow, MD, Park, B-G, Kim, S-L, Lee, C-U, Cha, S-M, Kim, D-J, Lee, Y, Friedmann, M, Kaspi, S, Maoz, D, Hundertmark, M, Street, RA, Tsapras, Y, Bramich, DM, Cassan, A, Dominik, M, Bachelet, E, Dong, S, Jaimes, RF, Horne, K, Mao, S, Menzies, J, Schmidt, R, Snodgrass, C, Steele, IA, Wambsganss, J, Skottfelt, J, Andersen, MI, Burgdorf, MJ, Ciceri, S, D'Ago, G, Evans, DF, Gu, S-H, Hinse, TC, Kerins, E, Korhonen, H, Kuffmeier, M, Mancini, L, Peixinho, N, Popovas, A, Rabus, M, Rahvar, S, Tronsgaard, R, Scarpetta, G, Southworth, J, Surdej, J, von Essen, C, Wang, Y-B, Wertz, O, TEAM, S, OGLE, GRP, KMTNET, GRP, WISE, GRP, TEAM, R, MINDSTEP, GRP, Science & Technology Facilities Council, and University of St Andrews. School of Physics and Astronomy

Subjects
Star (game theory), PROPER MOTIONS, GRAVITATIONAL LENSING EXPERIMENT, Brown dwarf, NDAS, FOS: Physical sciences, Astrophysics, gravitational lensing: micro, GALACTIC BULGE, Gravitational microlensing, Space (mathematics), brown dwarfs, stars: fundamental parameters, Astronomy and Astrophysics, Space and Planetary Science, 01 natural sciences, fundamental parameters [Stars], law.invention, micro [Gravitational lensing], EVENTS, Settore FIS/05 - Astronomia e Astrofisica, PLANET SENSITIVITY, SYSTEMS, law, Bulge, 0103 physical sciences, QB Astronomy, QD, 010303 astronomy & astrophysics, Red clump, Solar and Stellar Astrophysics (astro-ph.SR), QC, QB, Earth and Planetary Astrophysics (astro-ph.EP), Physics, Brown dwarfs, 010308 nuclear & particles physics, OGLE-III, Lens (optics), QC Physics, Astrophysics - Solar and Stellar Astrophysics, Parallax, PARALLAX SATELLITE MASS, SPITZER OBSERVATIONS, STARS, Astrophysics - Earth and Planetary Astrophysics
Abstract

We report on the mass and distance measurements of two single-lens events from the 2015 \emph{Spitzer} microlensing campaign. With both finite-source effect and microlens parallax measurements, we find that the lens of OGLE-2015-BLG-1268 is very likely a brown dwarf. Assuming that the source star lies behind the same amount of dust as the Bulge red clump, we find the lens is a $45\pm7$ $M_{\rm J}$ brown dwarf at $5.9\pm1.0$ kpc. The lens of of the second event, OGLE-2015-BLG-0763, is a $0.50\pm0.04$ $M_\odot$ star at $6.9\pm1.0$ kpc. We show that the probability to definitively measure the mass of isolated microlenses is dramatically increased once simultaneous ground- and space-based observations are conducted., Comment: 10 papers, 4 figures, 2 tables; ApJ in press

Published
2016

6. DETERMINING THE PHYSICAL LENS PARAMETERS OF THE BINARY GRAVITATIONAL MICROLENSING EVENT MOA-2009-BLG-016

Author

Hwang, K. -H., Han, C., Bond, I. A., Miyake, N., Abe, F., Bennett, D. P., Botzler, C. S., Fukui, A., Furusawa, K., Hayashi, F., Hearnshaw, J. B., Hosaka, S., Itow, Y., Kamiya, K., Kilmartin, P. M., Korpela, A., Lin, W., Ling, C. H., Makita, S., Masuda, K., Matsubara, Y., Muraki, Y., Nishimoto, K., Ohnishi, K., Perrott, Y. C., Rattenbury, N., Saito, To., Sako, T., Skuljan, L., Sullivan, D. J., Sumi, T., Suzuki, D., Sweatman, W. L., Tristram, J., Wada, K., L., P. C. M. Yock D., Depoy, Gaudi, B. S., Gould, A., Lee, C. -U., and Pogge, R. W.

Subjects
Physics, 010504 meteorology & atmospheric sciences, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Light curve, Gravitational microlensing, 01 natural sciences, law.invention, Einstein radius, Lens (optics), Gravitational lens, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, law, 0103 physical sciences, Orbital motion, Astrophysics::Earth and Planetary Astrophysics, Caustic (optics), Parallax, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), 0105 earth and related environmental sciences
Abstract

We report the result of the analysis of the light curve of the microlensing event MOA-2009-BLG-016. The light curve is characterized by a short-duration anomaly near the peak and an overall asymmetry. We find that the peak anomaly is due to a binary companion to the primary lens and the asymmetry of the light curve is explained by the parallax effect caused by the acceleration of the observer over the course of the event due to the orbital motion of the Earth around the Sun. In addition, we detect evidence for the effect of the finite size of the source near the peak of the event, which allows us to measure the angular Einstein radius of the lens system. The Einstein radius combined with the microlens parallax allows us to determine the total mass of the lens and the distance to the lens. We identify three distinct classes of degenerate solutions for the binary lens parameters, where two are manifestations of the previously identified degeneracies of close/wide binaries and positive/negative impact parameters, while the third class is caused by the symmetric cycloid shape of the caustic. We find that, for the best-fit solution, the estimated mass of the lower-mass component of the binary is (0.04 +- 0.01) M_sun, implying a brown-dwarf companion. However, there exists a solution that is worse only by \Delta\chi^2 ~ 3 for which the mass of the secondary is above the hydrogen-burning limit. Unfortunately, resolving these two degenerate solutions will be difficult as the relative lens-source proper motions for both are similar and small (~ 1 mas/yr) and thus the lens will remain blended with the source for the next several decades., Comment: 7 pages, 2 tables, and 5 figures

Published
2010

7. THE EXTREME MICROLENSING EVENT OGLE-2007-BLG-224: TERRESTRIAL PARALLAX OBSERVATION OF A THICK-DISK BROWN DWARF

Author

Gould, A., Udalski, A., Monard, B., Horne, K., Dong, Subo, Miyake, N., Sahu, K., Bennett, D. P., Wyrzykowski, Ł., Soszyński, I., Szymański, M. K., Kubiak, M., Pietrzyński, G., Szewczyk, O., Ulaczyk, K., Allen, W., Christie, G. W., Depoy, D. L., Gaudi, B. S., Han, C., Lee, C.-U., Mccormick, J., Natusch, T., Park, B.-G., Pogge, R. W., Allan, A., Bode, M. F., Bramich, D. M., Burgdorf, M. J., Dominik, M., Fraser, S. N., Kerins, E., Mottram, C., Snodgrass, C., Steele, I. A., Street, R., Tsapras, Y., Abe, F., Bond, I. A., Botzler, C. S., Fukui, A., Furusawa, K., Hearnshaw, J. B., Itow, Y., Kamiya, K., Kilmartin, P. M., Korpela, A., Lin, W., Ling, C. H., Masuda, K., Matsubara, Y., Muraki, Y., Nagaya, M., Ohnishi, K., Okumura, T., Perrott, Y. C., Rattenbury, N., Saito, To., Sako, T., Skuljan, L., Sullivan, D. J., Sumi, T., Sweatman, W. L., Tristram, P. J., Yock, P. C. M., Albrow, M., Beaulieu, J. P., Coutures, C., Calitz, H., Caldwell, J., Fouqué, P., Martin, Roland, Williams, A., Department of Astronomy (Ohio State University), Ohio State University [Columbus] (OSU), Astrophysics Research Institute [Liverpool] (ARI), Liverpool John Moores University (LJMU), Institut d'Astrophysique de Paris (IAP), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Astrophysique de Toulouse-Tarbes (LATT), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), and Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Astronomical Objects, Solar System, gravitational lensing, Brown dwarf, FOS: Physical sciences, Astrophysics, Gravitational microlensing, 01 natural sciences, law.invention, stars: low-mass, law, 0103 physical sciences, Thick disk, Astrophysics::Solar and Stellar Astrophysics, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Physics, [SDU.ASTR.SR]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], 010308 nuclear & particles physics, Astronomy and Astrophysics, [PHYS.ASTR.SR]Physics [physics]/Astrophysics [astro-ph]/Solar and Stellar Astrophysics [astro-ph.SR], Astrophysics - Astrophysics of Galaxies, Lens (optics), Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), astrometry, Astrophysics::Earth and Planetary Astrophysics, Parallax, Event (particle physics), brown dwarfs
Abstract

Parallax is the most fundamental technique to measure distances to astronomical objects. Although terrestrial parallax was pioneered over 2000 years ago by Hipparchus (ca. 140 BCE) to measure the distance to the Moon, the baseline of the Earth is so small that terrestrial parallax can generally only be applied to objects in the Solar System. However, there exists a class of extreme gravitational microlensing events in which the effects of terrestrial parallax can be readily detected and so permit the measurement of the distance, mass, and transverse velocity of the lens. Here we report observations of the first such extreme microlensing event OGLE-2007-BLG-224, from which we infer that the lens is a brown dwarf of mass M=0.056 +- 0.004 Msun, with a distance of 525 +- 40 pc and a transverse velocity of 113 +- 21 km/s. The velocity places the lens in the thick disk, making this the lowest-mass thick-disk brown dwarf detected so far. Follow-up observations may allow one to observe the light from the brown dwarf itself, thus serving as an important constraint for evolutionary models of these objects and potentially opening a new window on sub-stellar objects. The low a priori probability of detecting a thick-disk brown dwarf in this event, when combined with additional evidence from other observations, suggests that old substellar objects may be more common than previously assumed., Comment: ApJ Letters, in press, 15 pages including 2 figures

Published
2009

8. OGLE-2012-BLG-0563Lb : a Saturn-mass planet around an M dwarf with the mass constrained by Subaru AO imaging

Author

Fukui, A., Gould, A., Sumi, T., Bennett, D. P., Bond, I. A., Han, C., Suzuki, D., Beaulieu, J.-P., Batista, V., Udalski, A., Street, R. A., Tsapras, Y., Hundertmark, Markus Peter Gerhard, Abe, F., Bhattacharya, A., Freeman, M., Itow, Y., Ling, C. H., Koshimoto, N., Masuda, K., Matsubara, Y., Muraki, Y., Ohnishi, K., Philpott, L. C., Rattenbury, N., Saito, T., Sullivan, D. J., Tristram, P. J., Yonehara, A., Choi, J.-Y., Christie, G. W., DePoy, D. L., Dong, Subo, Drummond, J., Gaudi, B. S., Hwang, K.-H., Kavka, A., Lee, C.-U., McCormick, J., Natusch, T., Ngan, H., Park, H., Pogge, R. W., Shin, I.-G., Tan, T.-G., Yee, J. C., Szymański, M. K., Pietrzyński, G., Soszyński, I., Poleski, R., Kozłowski, S., Pietrukowicz, P., Ulaczyk, K., Wyrzykowski, Ł., Bramich, D. M., Browne, Paul, Dominik, Martin, Horne, Keith Douglas, Ipatov, S., Kains, N., Snodgrass, C., Steele, I. A., The Royal Society, Science & Technology Facilities Council, and University of St Andrews. School of Physics and Astronomy

Subjects
Metallicity, NDAS, FOS: Physical sciences, Astrophysics, Type (model theory), Gravitational microlensing, 01 natural sciences, Planet, 0103 physical sciences, QB Astronomy, 010303 astronomy & astrophysics, QC, QB, Earth and Planetary Astrophysics (astro-ph.EP), Physics, 010308 nuclear & particles physics, photometric [Techniques], Astronomy and Astrophysics, Planetary system, Mass ratio, Light curve, Exoplanet, Planetary systems, detection [Planets and satellites], gaseous planets [Planets and satellites], high angular resolution [Techniques], QC Physics, 13. Climate action, Space and Planetary Science, late-type [Stars], Astrophysics - Earth and Planetary Astrophysics
Abstract

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. With the help of a spectroscopic information about the source star obtained during the high-magnification state by Bensby et al., we find that the lens system is located at 1.3^{+0.6}_{-0.8} kpc from us, and consists of an M dwarf (0.34^{+0.12}_{-0.20} M_sun) orbited by a Saturn-mass planet (0.39^{+0.14}_{-0.23} M_Jup) at the projected separation of 0.74^{+0.26}_{-0.42} AU (close model) or 4.3^{+1.5}_{-2.5} AU (wide model). The probability of contamination in the host star's flux, which would reduce the masses by a factor of up to three, is estimated to be 17%. This possibility can be tested by future high-resolution imaging. We also estimate the (J-Ks) and (H-Ks) colors of the host star, which are marginally consistent with a low metallicity mid-to-early M dwarf, although further observations are required for the metallicity to be conclusive. This is the fifth sub-Jupiter-mass (0.2, Comment: 17 pages, 11 figures, an error in Figure 11 in the published version corrected

Published
2015

9. Spitzer Microlens Measurement of a Massive Remnant in a Well-Separated Binary

Author

Shvartzvald, Y., Udalski, A., Gould, A., Han, C., Bozza, V., Friedmann, M., Hundertmark, M., Beichman, C., Bryden, G., Calchi Novati, S., Carey, S., Fausnaugh, M., Gaudi, B. S., Henderson, C. B., Kerr, T., Pogge, R. W., Varricatt, W., Wibking, B., Yee, J. C., Zhu, W., Poleski, R., Pawlak, M., Szymański, M. K., Skowron, J., Mróz, P., Kozłowski, S., Wyrzykowski, Ł., Pietrukowicz, P., Pietrzyński, G., Soszyński, I., Ulaczyk, K., Choi, J.-Y., Park, H., Jung, Y. K., Shin, I.-G., Albrow, M. D., Park, B.-G., Kim, S.-L., Lee, C.-U., Cha, S.-M., Kim, D.-J., Lee, Y., Maoz, D., Kaspi, S., Street, R. A., Tsapras, Y., Bachelet, E., Dominik, M., Bramich, D. M., Horne, Keith, Snodgrass, C., Steele, I. A., Menzies, J., Figuera Jaimes, R., Wambsganss, J., Schmidt, R., Cassan, A., Ranc, C., Mao, S., Dong, Subo, D’Ago, G., Scarpetta, G., Verma, P., Jørgensen, U. G., Kerins, E., Skottfelt, J., Science & Technology Facilities Council, and University of St Andrews. School of Physics and Astronomy

Subjects
Astrophysics::High Energy Astrophysical Phenomena, black hole physics, bulge [Galaxy], NDAS, FOS: Physical sciences, Astrophysics, gravitational lensing: micro, Astrophysics::Cosmology and Extragalactic Astrophysics, Gravitational microlensing, Galaxy: bulge, micro [Gravitational lensing], stars: neutron, Bulge, Primary (astronomy), binaries: general, Space and Planetary Science, Astronomy and Astrophysics, QB Astronomy, Astrophysics::Solar and Stellar Astrophysics, Adaptive optics, QC, Astrophysics::Galaxy Astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), QB, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), general [Binaries], neutron [Stars], Black hole physics, Light curve, Black hole, Neutron star, QC Physics, Astrophysics - Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Parallax, Astrophysics - High Energy Astrophysical Phenomena
Abstract

We report the detection and mass measurement of a binary lens OGLE-2015-BLG-1285La,b, with the more massive component having $M_1>1.35\,M_\odot$ (80% probability). A main-sequence star in this mass range is ruled out by limits on blue light, meaning that a primary in this mass range must be a neutron star or black hole. The system has a projected separation $r_\perp= 6.1\pm 0.4\,{\rm AU}$ and lies in the Galactic bulge. These measurements are based on the "microlens parallax" effect, i.e., comparing the microlensing light curve as seen from $Spitzer$, which lay at $1.25\,{\rm AU}$ projected from Earth, to the light curves from four ground-based surveys, three in the optical and one in the near infrared. Future adaptive optics imaging of the companion by 30m class telescopes will yield a much more accurate measurement of the primary mass. This discovery both opens the path and defines the challenges to detecting and characterizing black holes and neutron stars in wide binaries, with either dark or luminous companions. In particular, we discuss lessons that can be applied to future $Spitzer$ and $Kepler$ K2 microlensing parallax observations., ApJ. accepted, 34 pages, 7 figures, 2 tables

Published
2015
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10. Red noise versus planetary interpretations in the microlensing event OGLE-2013-BLG-446

Author

Bachelet, E, Bramich, DM, Han, C, Greenhill, J, Street, RA, Gould, A, D'Ago, G, AlSubai, K, Dominik, M, Jaimes, RF, Horne, K, Hundertmark, M, Kains, N, Snodgrass, C, Steele, IA, Tsapras, Y, Albrow, MD, Batista, V, Beaulieu, J-P, Bennett, DP, Brillant, S, Caldwell, JAR, Cassan, A, Cole, A, Coutures, C, Dieters, S, Prester, DD, Donatowicz, J, Fouque, P, Hill, K, Marquette, J-B, Menzies, J, Pere, C, Ranc, C, Wambsganss, J, Warren, D, De Almeida, LA, Choi, J-Y, DePoy, DL, Dong, S, Hung, L-W, Hwang, K-H, Jablonski, F, Jung, YK, Kaspi, S, Klein, N, Lee, C-U, Maoz, D, Munoz, JA, Nataf, D, Park, H, Pogge, RW, Polishook, D, Shin, I-G, Shporer, A, Yee, JC, Abe, F, Bhattacharya, A, Bond, IA, Botzler, CS, Freeman, M, Fukui, A, Itow, Y, Koshimoto, N, Ling, CH, Masuda, K, Matsubara, Y, Muraki, Y, Ohnishi, K, Philpott, LC, Rattenbury, N, Saito, T, Sullivan, DJ, Sumi, T, Suzuki, D, Tristram, PJ, Yonehara, A, Bozza, V, Novati, SC, Ciceri, S, Galianni, P, Gu, S-H, Harpsoe, K, Hinse, TC, Jorgensen, UG, Juncher, D, Korhonen, H, Mancini, L, Melchiorre, C, Popovas, A, Postiglione, A, Rabus, M, Rahvar, S, Schmidt, RW, Scarpetta, G, Skottfelt, J, Southworth, J, Stabile, A, Surdej, J, Wang, X-B, Wertz, O, Collaboration, R, Collaboration, PLANET, Collaboration, FUN, Collaboration, MOA, Collaboration, M, The Royal Society, Science & Technology Facilities Council, and University of St Andrews. School of Physics and Astronomy

Subjects
Nuclear and High Energy Physics, NDAS, gravitational lensing: micro, planetary systems, techniques: photometric, FOS: Physical sciences, Astrophysics, Gravitational microlensing, micro [Gravitational lensing], Settore FIS/05 - Astronomia e Astrofisica, False positive paradox, QB Astronomy, QC, QB, Event (probability theory), Physics, Earth and Planetary Astrophysics (astro-ph.EP), High magnification, photometric [Techniques], Astronomy and Astrophysics, Light curve, Exoplanet, Planetary systems, QC Physics, 13. Climate action, Space and Planetary Science, Colors of noise, Parallax, Astrophysics - Earth and Planetary Astrophysics
Abstract

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. Real-time modeling of the event while it was still ongoing suggested the presence of an extremely low-mass companion (\sim 3M_\oplus ) to the lensing star, leading to substantial follow-up coverage of the light curve. We test and compare different models for the light curve and conclude that the data do not favour the planetary interpretation when systematic errors are taken into account., Comment: accepted ApJ 2015

Published
2015
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11. OGLE-2011-BLG-0265Lb: A JOVIAN MICROLENSING PLANET ORBITING AN M DWARF

Author

Skowron, J., Shin, I. -G., Udalski, A., Han, C., Sumi, T., Shvartzvald, Y., Gould, A., Dominis Prester, D., Street, R. A., Jørgensen, U. G., Bennett, D. P., Bozza, V., Szymański, M. K., Kubiak, M., Pietrzyński, G., Soszyński, I., Poleski, R., Kozłowski, S., Pietrukowicz, P., Ulaczyk, K., Wyrzykowski, Ł., OGLE Collaboration, Abe, F., Bhattacharya, A., Bond, I. A., Botzler, C. S., Freeman, M., Fukui, A., Fukunaga, D., Itow, Y., Ling, C. H., Koshimoto, N., Masuda, K., Matsubara, Y., Muraki, Y., Namba, S., Ohnishi, K., Philpott, L. C., Rattenbury, N., Saito, T., Sullivan, D. J., Suzuki, D., Tristram, P. J., Yock, P. C. M., MOA Collaboration, Maoz, D., Kaspi, S., Friedmann, M., Wise Group, Almeida, L. A., Batista, V., Christie, G., Choi, J. -Y., DePoy, D. L., Gaudi, B. S., Henderson, C., Hwang, K. -H., Jablonski, F., Jung, Y. K., Lee, C. -U., McCormick, J., Natusch, T., Ngan, H., Park, H., Pogge, R. W., Yee, J. C., μFUN Collaboration, Albrow, M. D., Bachelet, E., Beaulieu, J. -P., Brillant, S., Caldwell, J. A. R., Cassan, A., Cole, A., Corrales, E., Coutures, Ch., Dieters, S., Donatowicz, J., Fouqué, P., Greenhill, J., Kains, N., Kane, S. R., Kubas, D., Marquette, J. -B., Martin, R., Menzies, J., Pollard, K. R., Ranc, C., Sahu, K. C., Wambsganss, J., Williams, A., Wouters, D., PLANET Collaboration, Tsapras, Y., Bramich, D. M., Horne, K., Hundertmark, M., Snodgrass, C., Steele, I. A., RoboNet Collaboration, Alsubai, K. A., Browne, P., Burgdorf, M. J., Calchi Novati, S., Dodds, P., Dominik, M., Dreizler, S., Fang, X. -S., Gu, C. -H., Hardis, Harpsøe, K., Hessman, F. V., Hinse, T. C., Hornstrup, A., Jessen-Hansen, J., Kerins, E., Liebig, C., Lund, M., Lundkvist, M., Mancini, L., Mathiasen, M., Penny, M. T., Rahvar, S., RICCI, DAVIDE, Scarpetta, G., Skottfelt, J., Southworth, J., Surdej, J., Tregloan-Reed, J., Wertz, O., MiNDSTEp Consortium, ITA, USA, GBR, DEU, ESP, BEL, KOR, DNK, IND, IRN, MEX, The Royal Society, Science & Technology Facilities Council, and University of St Andrews. School of Physics and Astronomy

Subjects
Star (game theory), FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, GALACTIC BULGE, Gravitational microlensing, Jovian, JUPITER/SATURN ANALOG, Jupiter, Settore FIS/05 - Astronomia e Astrofisica, Planet, Bulge, ANGULAR SIZES, QB Astronomy, Astrophysics::Solar and Stellar Astrophysics, planetary systems, QC, Astrophysics::Galaxy Astrophysics, QB, Earth and Planetary Astrophysics (astro-ph.EP), Physics, Astronomy and Astrophysics, 3rd-DAS, Planetary system, MASS PLANET, Light curve, OGLE-III, SNOW LINE, GRAVITATIONAL BINARY-LENS, QC Physics, SURFACE BRIGHTNESS RELATIONS, GIANT PLANETS, Space and Planetary Science, micro [gravitational lensing], Astrophysics::Earth and Planetary Astrophysics, STARS, Astrophysics - Earth and Planetary Astrophysics
Abstract

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. The final microlensing solution remains, however, degenerate yielding two possible configurations of the planet and the host star. In the case of the preferred solution, the mass of the planet is $M_{\rm p} = 0.9\pm 0.3\ M_{\rm J}$, and the planet is orbiting a star with a mass $M = 0.22\pm 0.06\ M_\odot$. The second possible configuration (2$\sigma$ away) consists of a planet with $M_{\rm p}=0.6\pm 0.3\ M_{\rm J}$ and host star with $M=0.14\pm 0.06\ M_\odot$. The system is located in the Galactic disk 3 -- 4 kpc towards the Galactic bulge. In both cases, with an orbit size of 1.5 -- 2.0 AU, the planet is a "cold Jupiter" -- located well beyond the "snow line" of the host star. Currently available data make the secure selection of the correct solution difficult, but there are prospects for lifting the degeneracy with additional follow-up observations in the future, when the lens and source star separate., Comment: 10 pages, 2 tables, 5 figures. Accepted in ApJ

Published
2015

12. OGLE-2016-BLG-0168 Binary Microlensing Event: Prediction and Confirmation of the Microlens Parallax Effect from Space-based Observations

Author

Shin, I. -G., Udalski, A., Yee, J. C., Novati, S. Calchi, Han, C., Skowron, J., Mr��z, P., Soszy��ski, I., Poleski, R., Szyma��ski, M. K., Koz��owski, S., Pietrukowicz, P., Ulaczyk, K., Pawlak, M., Albrow, M. D., Gould, A., Chung, S. -J., Hwang, K. -H., Jung, Y. K., Ryu, Y. -H., Zhu, W., Cha, S. -M., Kim, D. -J., Kim, H. -W., Kim, S. -L., Lee, C. -U., Lee, Y., Park, B. -G., Pogge, R. W., Beichman, C., Bryden, G., Carey, S., Gaudi, B. S., Henderson, C. B., and Shvartzvald, Y.

Subjects
Microlens, Physics, 010308 nuclear & particles physics, Astrophysics::Instrumentation and Methods for Astrophysics, Brown dwarf, FOS: Physical sciences, Astronomy, Astronomy and Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Light curve, Gravitational microlensing, 01 natural sciences, Stars, Neutron star, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Planet, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, Astrophysics::Earth and Planetary Astrophysics, Parallax, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics
Abstract

The microlens parallax is a crucial observable for conclusively identifying the nature of lens systems in microlensing events containing or composed of faint (even dark) astronomical objects such as planets, neutron stars, brown dwarfs, and black holes. With the commencement of a new era of microlensing in collaboration with space-based observations, the microlens parallax can be routinely measured. In addition, space-based observations can provide opportunities to verify the microlens parallax measured from ground-only observations and to find a unique solution of the lensing lightcurve analysis. However, since most space-based observations cannot cover the full lightcurves of lensing events, it is also necessary to verify the reliability of the information extracted from fragmentary space-based lightcurves. We conduct a test based on the microlensing event OGLE-2016-BLG-0168 created by a binary lens system consisting of almost equal mass M-dwarf stars to demonstrate that it is possible to verify the microlens parallax and to resolve degeneracies by using the space-based lightcurve even though the observations are fragmentary. Since space-based observatories will frequently produce fragmentary lightcurves due to their short observing windows, the methodology of this test will be useful for next-generation microlensing experiments that combine space-based and ground-based collaboration., 9 pages, 5 figures, 3 tables, submitted in ApJ

Published
2017

13. MOA-2011-BLG-262Lb: A Sub-Earth-Mass Moon Orbiting a Gas Giant Primary or a High Velocity Planetary System in the Galactic Bulge

Author

Bennett, D.P., Batista, V., Bond, I.A., Bennett, C.S., Suzuki, D., Beaulieu, J.-P., Udalski, A., Donatowicz, J., Bozza, V., Abe, F., Botzler, C.S., Freeman, M., Fukunaga, D., Fukui, A., Itow, Y., Koshimoto, N., Ling, C.H., Masuda, K., Matsubara, Y., Muraki, Y., Namba, S., Ohnishi, K., Rattenbury, N.J., Saito, T., Sullivan, D.J., Sumi, T., Sweatman, W.L., Tristram, P.J., Tsurumi, N., Wada, K., Yock, P.C.M., Albrow, M.D., Bachelet, E., Brillant, S., Caldwell, J.A.R., Cassan, A., Cole, A.A., Corrales, E., Coutures, C., Dieters, S., Dominis Prester, D., Fouqué, P., Greenhill, J., Horne, K., Koo, J.-R., Kubas, D., Marquette, J.-B., Martin, R., Menzies, J.W., Sahu, K.C., Wambsganss, J., Williams, A., Zub, M., Choi, J.Y., Depoy, D.L., Dong, S., Gaudi, B.S., Gould, A., Han, C., Henderson, C.B., McGregor, D., Lee, C.-U., Pogge, R.W., Shin, I.-G., Yee, J.C., Szymański, M.K., Skowron, J., Poleski, R., Kozłowski, S., Wyrzykowski, Ł., Kubiak, M., Pietrukowicz, P., Pietrzyński, G., Soszyński, I., Ulaczyk, K., Tsapras, Y., Street, R.A., Dominik, M., Bramich, D.M., Browne, P., Hundertmark, M., Kains, N., Snodgrass, C., Steele, I.A., Dekany, I., Gonzalez, O.A., Heyrovský, D., Kandori, R., Kerins, E., Lucas, P.W., Minniti, D., Nagayama, T., Rejkuba, M., Robin, A.C., Saito, A.R., The Royal Society, Science & Technology Facilities Council, University of St Andrews. School of Physics and Astronomy, Ohio State University [Columbus] (OSU), Institut d'Astrophysique de Paris (IAP), Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Astronomical Observatory [Warsaw], Faculty of Physics [Warsaw] (FUW), University of Warsaw (UW)-University of Warsaw (UW), Okayama Astrophysical Observatory, National Astronomical Observatory of Japan (NAOJ), Nagoya University, Osaka University [Osaka], Institut de recherche en astrophysique et planétologie (IRAP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Univers, Transport, Interfaces, Nanostructures, Atmosphère et environnement, Molécules (UMR 6213) (UTINAM), Université de Franche-Comté (UFC), and Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)

Subjects
Proper motion, 010504 meteorology & atmospheric sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, Gravitational microlensing, 7. Clean energy, 01 natural sciences, micro [Gravitational lensing], Jupiter, Planet, 0103 physical sciences, QB Astronomy, 010303 astronomy & astrophysics, ComputingMilieux_MISCELLANEOUS, QC, Astrophysics::Galaxy Astrophysics, QB, 0105 earth and related environmental sciences, Physics, Exomoon, Giant planet, Astronomy, Astronomy and Astrophysics, Planetary system, Exoplanet, Planetary systems, QC Physics, 13. Climate action, Space and Planetary Science, Astrophysics::Earth and Planetary Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], BDC
Abstract

D.P.B. was supported by grants NASA-NNX12AF54G, JPL-RSA 1453175 and NSF AST-1211875. This MOA project is supported by the grants JSPS18253002 and JSPS20340052. T.S. acknowledges the financial support from the JSPS, JSPS23340044, JSPS24253004. This work was partially supported by a NASA Keck PI Data Award, administered by the NASA Exoplanet Science Institute. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. B.S.G. and A.G. were supported by NSF grant AST 110347. B.S.G., A.G., R.P.G. were supported by NASA grant NNX12AB99G. S.D. was partly supported through a Ralph E. and Doris M. Hansmann Membership at the IAS and by NSF grant AST-0807444. Work by J.C.Y. was performed in part under contract with the California Institute of Technology (Caltech) funded by NASA through the Sagan Fellowship Program. The OGLE project has received funding from the European Research Council under the European Community's Seventh Framework Programme (FP7/2007-2013)/ERC grant agreement No. 246678 to A.U. D.H. was supported by Czech Science Foundation grant GACR P209/10/1318. D.M.B., M.D., K.H., C.S., R.A.S., M.H. and Y.T. are supported by NPRP grant NPRP-09-476-1-78 from the Qatar National Research Fund (a member of the Qatar Foundation). 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 argument for an exomoon hinges on the system being relatively close to the Sun. The data constrain the product MLπrel where ML is the lens system mass and πrel is the lens-source relative parallax. If the lens system is nearby (large πrel), then ML is small (a few Jupiter masses) and the companion is a sub-Earth-mass exomoon. The best-fit solution has a large lens-source relative proper motion, μrel = 19.6 ± 1.6 mas yr–1, which would rule out a distant lens system unless the source star has an unusually high proper motion. However, data from the OGLE collaboration nearly rule out a high source proper motion, so the exoplanet+exomoon model is the favored interpretation for the best fit model. However, there is an alternate solution that has a lower proper motion and fits the data almost as well. This solution is compatible with a distant (so stellar) host. A Bayesian analysis does not favor the exoplanet+exomoon interpretation, so Occam's razor favors a lens system in the bulge with host and companion masses of M host = 0.12 +0.19-0.06 MΘ and mcomp = 18+28-10M⊕, at a projected separation of a⊥ = 0.84+0.25−0.14 AU. The existence of this degeneracy is an unlucky accident, so current microlensing experiments are in principle sensitive to exomoons. In some circumstances, it will be possible to definitively establish the mass of such lens systems through the microlensing parallax effect. Future experiments will be sensitive to less extreme exomoons. Publisher PDF

Published
2014

14. A Super-Jupiter orbiting a late-type star: A refined analysis of microlensing event OGLE-2012-BLG-0406

Author

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

Subjects
Perturbation (astronomy), FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Gravitational microlensing, Einstein radius, micro [Gravitational lensing], Super-Jupiter, Settore FIS/05 - Astronomia e Astrofisica, Planet, QB Astronomy, Astrophysics::Solar and Stellar Astrophysics, QC, Astrophysics::Galaxy Astrophysics, QB, Physics, Earth and Planetary Astrophysics (astro-ph.EP), general [Binaries], Astronomy and Astrophysics, Planetary systems, QC Physics, Space and Planetary Science, Orbital motion, Astrophysics::Earth and Planetary Astrophysics, Late-type star, Parallax, Astrophysics - Earth and Planetary Astrophysics
Abstract

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. We find that the event was caused by a $2.73\pm 0.43\ M_{\rm J}$ planet orbiting a $0.44\pm 0.07\ M_{\odot}$ early M-type star. The distance to the lens is $4.97\pm 0.29$\ kpc and the projected separation between the host star and its planet at the time of the event is $3.45\pm 0.26$ AU. We find that the additional coverage provided by follow-up observations, especially during the planetary perturbation, leads to a more accurate determination of the physical parameters of the lens., 9 pages, 4 figures, accepted by ApJ

Published
2013

15. A giant planet beyond the snow line in microlensing event OGLE-2011-BLG-0251

Author

Kains, N., Street, R.A., Choi, J.-Y., Han, C., Udalski, A., Almeida, L.A., Jablonski, F., Tristram, P.J., Jørgensen, Uffe Gråe, Szymański, M.K., Kubiak, M., Pietrzyński, G., Soszyński, I., Poleski, R., Kozłowski, S., Pietrukowicz, P., Ulaczyk, K., Wyrzykowski, Ł., Skowron, J., Tsapras, Y., Alsubai, K.A., Bozza, V., Browne, P., Burgdorf, M. J., Calchi Novati, S., Dodds, P., Dominik, M., Dreizler, S., Fang, X.-S., Grundahl, F., Gu, C.-H., Hardis, S., Harpsøe, Kennet Bomann West, Hessman, F. V., Hinse, T. C., Hornstrup, Allan, Hundertmark, M., Jessen-Hansen, Jens, Kerins, E., Liebig, C., Lund, M., Lundkvist, M., Mancini, L., Mathiasen, M., Penny, M. T., Rahvar, S., Ricci, D., Sahu, K.C., Scarpetta, G., Skottfelt, J., Snodgrass, C., Southworth, J., Surdej, J., Tregloan-Reed, J., Wambsganss, J., Wertz, O., Bajek, D., Bramich, D.M., Horne, K., Ipatov, S., Steele, I.A., Abe, F., Bennett, D.P., Bond, I.A., Botzler, C.S., Chote, P., Freeman, M., Fukui, A., Furusawa, K., Itow, Y., Ling, C.H., Masuda, K., Matsubara, Y, Miyake, N., Muraki, Y., Ohnishi, K., Rattenbury, N., Saito, T., Sullivan, D.J., Sumi, T., Suzuki, D., Suzuki, K., Sweatman, W.L., Takino, S., Wada, K., Yock, P.C.M., Allen, W., Batista, V., Chung, S.-J., Christie, G., Depoy, D.L., Drummond, J., Gaudi, B.S., Gould, A., Henderson, C., Jung, Y.K., Koo, J.-R., Lee, C.-U., McCormick, J., McGregor, D., Muñoz, J.A., Natusch, T., Ngan, H., Park, H., Pogge, R.W., Shin, I.-G., Yee, J., Albrow, M.D., Bachelet, E., Beaulieu, J.-P., Brillant, S., Caldwell, J.A.R., Cassan, A., Cole, A., Corrales, E., Coutures, Ch., Dieters, S., Dominis Prester, D., Donatowicz, J., Fouqué, P., Greenhill, J., Kane, S.R., Kubas, D., Marquette, J.-B., Martin, R., Meintjes, P., Menzies, J., Pollard, K.R., Williams, A., Wouters, D., Zub, M., Science & Technology Facilities Council, and University of St Andrews. School of Physics and Astronomy

Subjects
planets and satellites: detection, 010504 meteorology & atmospheric sciences, Satellites, bulge [Galaxy], FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Discovery, Gravitational microlensing, 01 natural sciences, Galaxy: bulge, Einstein radius, Lens, gravitational lensing: weak, Settore FIS/05 - Astronomia e Astrofisica, Planet, Snow, 0103 physical sciences, gravitational lensing, weak, planets and satellites, detection, planetary systems, Galaxy, bulge, Binary, QB Astronomy, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences, QB, Physics, Earth and Planetary Astrophysics (astro-ph.EP), Giant planet, Systems, Search, Astronomy and Astrophysics, Radius, Frequency, Planetary system, Mass ratio, Mass, Light curve, Stars, Algorithm, detection [Planets and satellites], Planetary systems, Space and Planetary Science, Dwarf, Astrophysics::Earth and Planetary Astrophysics, weak [Gravitational lensing], Astrophysics - Earth and Planetary Astrophysics
Abstract

We present the analysis of the gravitational microlensing event OGLE-2011-BLG-0251. This anomalous event was observed by several survey and follow-up collaborations conducting microlensing observations towards the Galactic Bulge. Based on detailed modelling of the observed light curve, we find that the lens is composed of two masses with a mass ratio q=1.9 x 10^-3. Thanks to our detection of higher-order effects on the light curve due to the Earth's orbital motion and the finite size of source, we are able to measure the mass and distance to the lens unambiguously. We find that the lens is made up of a planet of mass 0.53 +- 0.21,M_Jup orbiting an M dwarf host star with a mass of 0.26 +- 0.11 M_Sun. The planetary system is located at a distance of 2.57 +- 0.61 kpc towards the Galactic Centre. The projected separation of the planet from its host star is d=1.408 +- 0.019, in units of the Einstein radius, which corresponds to 2.72 +- 0.75 AU in physical units. We also identified a competitive model with similar planet and host star masses, but with a smaller orbital radius of 1.50 +- 0.50 AU. The planet is therefore located beyond the snow line of its host star, which we estimate to be around 1-1.5 AU., 12 pages, 7 figures, 3 tables; A&A in press

Published
2013
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16. Microlensing Discovery of a Population of Very Tight, Very Low-mass Binary Brown Dwarfs

Author

Choi, J.-Y., Han, C., Udalski, A., Sumi, T., Gaudi, B. S., Gould, A., Bennett, D. P., Dominik, M., Beaulieu, J.-P., Tsapras, Y., Bozza, V., Abe, F., Bond, I. A., Botzler, C. S., Chote, P., Freeman, M., Fukui, A., Furusawa, K., Itow, Y., Ling, C. H., Masuda, K., Matsubara, Y., Miyake, N., Muraki, Y., Ohnishi, K., Rattenbury, N. J., Saito, To., Sullivan, D. J., Suzuki, K., Sweatman, W. L., Suzuki, D., Takino, S., Tristram, P. J., Wada, K., Yock, P. C. M., The MOA Collaboration, Szymański, M. K., Kubiak, M., Pietrzyński, G., Soszyński, I., Skowron, J., Kozłowski, S., Poleski, R., Ulaczyk, K., Wyrzykowski, Ł., Pietrukowicz, P., The OGLE Collaboration, Almeida, L. A., DePoy, D. L., Dong, Subo, Gorbikov, E., Jablonski, F., Henderson, C. B., Hwang, K.-H., Janczak, J., Jung, Y.-K., Kaspi, S., Lee, C.-U., Malamud, U., Maoz, D., McGregor, D., Muñoz, J. A., Park, B.-G., Park, H., Pogge, R. W., Shvartzvald, Y., Shin, I.-G., Yee, J. C., The μFUN Collaboration, Alsubai, K. A., Browne, P., Burgdorf, M. J., Calchi Novati, S., Dodds, P., Fang, X.-S., Finet, F., Glitrup, M., Grundahl, F., Gu, S.-H., Hardis, S., Harpsøe, K., Hinse, T. C., Hornstrup, A., Hundertmark, M., Jessen-Hansen, J., Jrgensen, U. G., Kains, N., Kerins, E., Liebig, C., Lund, M. N., Lundkvist, M., Maier, G., Mancini, L., Mathiasen, M., Penny, M. T., Rahvar, S., Ricci, D., Scarpetta, G., Skottfelt, J., Snodgrass, C., Southworth, J., Surdej, J., Tregloan-Reed, J., Wambsganss, J., Wertz, O., Zimmer, F., MiNDSTEp Consortium, The, Albrow, M. D., Bachelet, E., Batista, V., Brillant, S., Cassan, A., Cole, A. A., Coutures, C., Dieters, S., Dominis Prester, D., Donatowicz, J., Fouqué, P., Greenhill, J., Kubas, D., Marquette, J.-B., Menzies, J. W., Sahu, K. C., Zub, M., The PLANET Collaboration, Bramich, D. M., Horne, K., Steele, I. A., Street, R. A., The RoboNet Collaboration, Science & Technology Facilities Council, and University of St Andrews. School of Physics and Astronomy

Subjects
binaries: general, gravitational lensing: micro, 010504 meteorology & atmospheric sciences, Population, Events, Brown dwarf, Minimum mass, Binary number, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Gravitational microlensing, 01 natural sciences, micro [Gravitational lensing], Settore FIS/05 - Astronomia e Astrofisica, 0103 physical sciences, QB Astronomy, Astrophysics::Solar and Stellar Astrophysics, education, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences, QB, Physics, education.field_of_study, Galactic bulge, general [Binaries], Systems, Search, Astronomy and Astrophysics, Stars, Extrasolar planets, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Astrophysics::Earth and Planetary Astrophysics, Low Mass, Gravitational lens
Abstract

Although many models have been proposed, the physical mechanisms responsible for the formation of low-mass brown dwarfs are poorly understood. The multiplicity properties and minimum mass of the brown-dwarf mass function provide critical empirical diagnostics of these mechanisms. We present the discovery via gravitational microlensing of two very low-mass, very tight binary systems. These binaries have directly and precisely measured total system masses of 0.025 Msun and 0.034 Msun, and projected separations of 0.31 AU and 0.19 AU, making them the lowest-mass and tightest field brown-dwarf binaries known. The discovery of a population of such binaries indicates that brown dwarf binaries can robustly form at least down to masses of ~0.02 Msun. Future microlensing surveys will measure a mass-selected sample of brown-dwarf binary systems, which can then be directly compared to similar samples of stellar binaries., 7 pages, 5 figures, 3 tables, ApJ submitted

Published
2013

17. MOA-2010-BLG-328Lb: A SUB-NEPTUNE ORBITING VERY LATE M DWARF?

Author

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

Subjects
gravitational lensing: micro, planetary systems, 010504 meteorology & atmospheric sciences, FOS: Physical sciences, Astrophysics, Gravitational microlensing, 01 natural sciences, micro [Gravitational lensing], Settore FIS/05 - Astronomia e Astrofisica, Neptune, Planet, 0103 physical sciences, QB Astronomy, 010303 astronomy & astrophysics, QC, 0105 earth and related environmental sciences, QB, Physics, Earth and Planetary Astrophysics (astro-ph.EP), Xallarap, Astronomy and Astrophysics, Planetary systems, QC Physics, Space and Planetary Science, Orbital motion, Parallax, Event (particle physics), Astrophysics - Earth and Planetary Astrophysics
Abstract

We analyze the planetary microlensing event MOA-2010-BLG-328. The best fit yields host and planetary masses of Mh = 0.11+/-0.01 M_{sun} and Mp = 9.2+/-2.2M_Earth, corresponding to a very late M dwarf and sub-Neptune-mass planet, respectively. The system lies at DL = 0.81 +/- 0.10 kpc with projected separation r = 0.92 +/- 0.16 AU. Because of the host's a-priori-unlikely close distance, as well as the unusual nature of the system, we consider the possibility that the microlens parallax signal, which determines the host mass and distance, is actually due to xallarap (source orbital motion) that is being misinterpreted as parallax. We show a result that favors the parallax solution, even given its close host distance. We show that future high-resolution astrometric measurements could decisively resolve the remaining ambiguity of these solutions., Comment: 30 pages, 6 figures. accepted for publication in ApJ. Figure 1 and 2 are updated

Published
2013

18. Microlensing Binaries with Candidate Brown Dwarf Companions

Author

Shin, I.-G., Han, C., Gould, A., Udalski, A., Sumi, T., Dominik, M., Beaulieu, J.-P., Tsapras, Y., Bozza, V., Szymański, M. K., Kubiak, M., Soszyński, I., Pietrzyński, G., Poleski, R., Ulaczyk, K., Pietrukowicz, P., Kozłowski, S., Skowron, J., Wyrzykowski, Ł., The OGLE Collaboration, Abe, F., Bennett, D. P., Bond, I. A., Botzler, C. S., Freeman, M., Fukui, A., Furusawa, K., Hayashi, F., Hearnshaw, J. B., Hosaka, S., Itow, Y., Kamiya, K., Kilmartin, P. M., Kobara, S., Korpela, A., Lin, W., Ling, C. H., Makita, S., Masuda, K., Matsubara, Y., Miyake, N., Muraki, Y., Nagaya, M., Nishimoto, K., Ohnishi, K., Okumura, T., Omori, K., Perrott, Y. C., Rattenbury, N., Saito, To., Skuljan, L., Sullivan, D. J., Suzuki, D., Sweatman, W. L., Tristram, P. J., Wada, K., Yock, P. C. M., The MOA Collaboration, Christie, G. W., Depoy, D. L., Dong, S., Gal-Yam, A., Gaudi, B. S., Hung, L.-W., Janczak, J., Kaspi, S., Maoz, D., McCormick, J., McGregor, D., Moorhouse, D., Muñoz, J. A., Natusch, T., Nelson, C., Pogge, R. W., Tan, T.-G., Polishook, D., Shvartzvald, Y., Shporer, A., Thornley, G., Malamud, U., Yee, J. C., Choi, J.-Y., Jung, Y.-K., Park, H., Lee, C.-U., Park, B.-G., Koo, J.-R., The μFUN Collaboration, Bajek, D., Bramich, D. M., Browne, P., Horne, K., Ipatov, S., Snodgrass, C., Steele, I., Street, R., Alsubai, K. A., Burgdorf, M. J., Calchi Novati, S., Dodds, P., Dreizler, S., Fang, X.-S., Grundahl, F., Gu, C.-H., Hardis, S., Harpsøe, Kennet Bomann West, Hinse, T. C., Hundertmark, M., Jessen-Hansen, J., Jørgensen, U. G., Kains, N., Kerins, E., Liebig, C., Lund, Mikkel Nørup, Lundkvist, M., Mancini, L., Mathiasen, M., Hornstrup, A., Penny, M. T., Proft, S., Rahvar, S., Ricci, D., Scarpetta, G., Skottfelt, Jesper Fælling, Southworth, J., Surdej, J., Tregloan-Reed, J., Wertz, O., Zimmer, F., Albrow, M. D., Batista, V., Brillant, S., Caldwell, J. A. R., Calitz, J. J., Cassan, A., Cole, A., Cook, K. H., Corrales, E., Coutures, Ch., Dieters, S., Dominis Prester, D., Donatowicz, J., Fouqué, P., Greenhill, J., Hill, K., Hoffman, M., Kane, S. R., Kubas, D., Marquette, J.-B., Martin, R., Meintjes, P., Menzies, J., Pollard, K. R., Sahu, K. C., Wambsganss, J., Williams, A., Vinter, Christian, and Zub, M.

Subjects
Physics, 010308 nuclear & particles physics, Brown dwarf, FOS: Physical sciences, Astronomy and Astrophysics, gravitational lensing: micro, Astrophysics, Light curve, Gravitational microlensing, 01 natural sciences, Einstein radius, Stars, binaries: general, Settore FIS/05 - Astronomia e Astrofisica, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Planet, 0103 physical sciences, brown dwarfs, Parallax, Low Mass, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR)
Abstract

Brown dwarfs are important objects because they may provide a missing link between stars and planets, two populations that have dramatically different formation history. In this paper, we present the candidate binaries with brown dwarf companions that are found by analyzing binary microlensing events discovered during 2004 - 2011 observation seasons. Based on the low mass ratio criterion of q < 0.2, we found 7 candidate events, including OGLE-2004-BLG-035, OGLE-2004-BLG-039, OGLE-2007-BLG-006, OGLE-2007-BLG-399/MOA-2007-BLG-334, MOA-2011-BLG-104/OGLE-2011-BLG-0172, MOA-2011-BLG-149, and MOA-201-BLG-278/OGLE-2011-BLG-012N. Among them, we are able to confirm that the companions of the lenses of MOA-2011-BLG-104/OGLE-2011-BLG-0172 and MOA-2011-BLG-149 are brown dwarfs by determining the mass of the lens based on the simultaneous measurement of the Einstein radius and the lens parallax. The measured mass of the brown dwarf companions are (0.02 +/- 0.01) M_Sun and (0.019 +/- 0.002) M_Sun for MOA-2011-BLG-104/OGLE-2011-BLG-0172 and MOA-2011-BLG-149, respectively, and both companions are orbiting low mass M dwarf host stars. More microlensing brown dwarfs are expected to be detected as the number of lensing events with well covered light curves increases with new generation searches., 10 pages, 9 figures, 4 tables

Published
2012

19. MOA-2010-BLG-477Lb: constraining the mass of a microlensing planet from microlensing parallax, orbital motion and detection of blended light

Author

Bachelet, E., Shin, I.-G., Han, C., Fouqué, P., Gould, A., Menzies, J.W., Beaulieu, J.-P., Bennett, D.P., Bond, I.A., Dong, Subo, Heyrovský, D., Marquette, J.-B., Marshall, J., Skowron, J., Street, R.A., Sumi, T., Udalski, A., Abe, L., Agabi, K., Albrow, M.D., Allen, W., Bertin, E., Bos, M., Bramich, D.M., Chavez, J., Christie, G.W., Cole, A.A., Crouzet, N., Dieters, S., Dominik, M., Drummond, J., Greenhill, J., Guillot, T., Henderson, C.B., Hessman, F.V., Horne, K., Hundertmark, M., Johnson, J.A., Jørgensen, U.G., Kandori, R., Liebig, C., Mékarnia, D., McCormick, J., Moorhouse, D., Nagayama, T., Nataf, D., Natusch, T., Nishiyama, S., Rivet, J.P., Sahu, K.C., Shvartzvald, Y., Thornley, G., Tomczak, A.R., Tsapras, Y., Yee, J.C., Batista, V., Bennett, C.S., Brillant, S., Caldwell, J.A.R., Cassan, A., Corrales, E., Coutures, C., Dominis Prester, D., Donatowicz, J., Kubas, D., Martin, Roland, Williams, A., Zub, M., The PLANET Collaboration, De Almeida, L., Depoy, D.L., Gaudi, B.S., Hung, L.-W., Jablonski, F., Kaspi, S., Klein, N., Lee, C.-U., Lee, Y., Koo, J.-R., Maoz, D., Muñoz, J.A., Pogge, R.W., Polishook, D., Shporer, A., The FUN Collaboration, Abe, F., Botzler, C.S., Chote, P., Freeman, M., Fukui, A., Furusawa, K., Harris, P., Itow, Y., Kobara, S., Ling, C.H., Masuda, K., Matsubara, Y., Miyake, N., Ohmori, K., Ohnishi, K., Rattenbury, N.J., Saito, To., Sullivan, D.J., Suzuki, D., Sweatman, W.L., Tristram, P.J., Wada, K., Yock, P.C.M., The MOA Collaboration, Szymanski, M.K., Soszynski, I., Kubiak, M., Poleski, R., Ulaczyk, K., Pietrzynski, G., Wyrzykowski, L., The OGLE Collaboration, Kains, N., Snodgrass, C., Steele, I.A., The RoboNet Collaboration, Alsubai, K.A., Bozza, V., Browne, P., Burgdorf, M.J., Calchi Novati, S., Dodds, P., Dreizler, S., Finet, F., Gerner, T., Hardis, S., Harpsøe, K., Hinse, T.C., Kerins, E., Mancini, L., Mathiasen, M., Penny, M.T., Proft, S., Rahvar, S., Ricci, D., Scarpetta, G., Schäfer, S., Schönebeck, F., Southworth, J., Surdej, J., Wambsganss, J., The MiNDSTEp Consortium, Joseph Louis LAGRANGE (LAGRANGE), Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), and Laboratoire de Cosmologie, Astrophysique Stellaire & Solaire, de Planétologie et de Mécanique des Fluides (CASSIOPEE)

Subjects
gravitational lensing: micro, planetary systems, FOS: Physical sciences, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Gravitational microlensing, 01 natural sciences, 7. Clean energy, Einstein radius, Settore FIS/05 - Astronomia e Astrofisica, Planet, 0103 physical sciences, Astrophysics::Solar and Stellar Astrophysics, 010306 general physics, 010303 astronomy & astrophysics, ComputingMilieux_MISCELLANEOUS, Astrophysics::Galaxy Astrophysics, Physics, Earth and Planetary Astrophysics (astro-ph.EP), Giant planet, Astronomy and Astrophysics, Mass ratio, Light curve, Orbit, 13. Climate action, Space and Planetary Science, Orbital motion, micro [gravitational lensing], gravitational lensing: micro, planetary systems, Astrophysics::Earth and Planetary Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Astrophysics - Earth and Planetary Astrophysics
Abstract

Microlensing detections of cool planets are important for the construction of an unbiased sample to estimate the frequency of planets beyond the snow line, which is where giant planets are thought to form according to the core accretion theory of planet formation. In this paper, we report the discovery of a giant planet detected from the analysis of the light curve of a high-magnification microlensing event MOA-2010-BLG-477. The measured planet-star mass ratio is $q=(2.181\pm0.004)\times 10^{-3}$ and the projected separation is $s=1.1228\pm0.0006$ in units of the Einstein radius. The angular Einstein radius is unusually large $\theta_{\rm E}=1.38\pm 0.11$ mas. Combining this measurement with constraints on the "microlens parallax" and the lens flux, we can only limit the host mass to the range $0.13, Comment: 3 Tables, 12 Figures, accepted in ApJ

Published
2012

20. Characterizing Lenses and Lensed Stars of High-magnification Single-lens Gravitational Microlensing Events with Lenses Passing over Source Stars

Author

Choi, J.-Y., Shin, I.-G., Park, S.-Y., Han, C., Gould, A., Sumi, T., Udalski, A., Beaulieu, J.-P., Street, R., Dominik, M., Allen, W., Almeida, L. A., Bos, M., Christie, G. W., Depoy, D. L., Dong, S., Drummond, J., Gal-Yam, A., Gaudi, B. S., Henderson, C. B., Hung, L.-W., Jablonski, F., Janczak, J., Lee, C.-U., Mallia, F., Maury, A., McCormick, J., McGregor, D., Monard, L. A. G., Moorhouse, D., Muñoz, J. A., Natusch, T., Nelson, C., Park, B.-G., Pogge, R. W., 'TG\\' Tan, T.-G., Thornley, G., Yee, J. C., The μFUN Collaboration, Abe, F., Barnard, E., Baudry, J., Bennett, D. P., Bond, I. A., Botzler, C. S., Freeman, M., Fukui, A., Furusawa, K., Hayashi, F., Hearnshaw, J. B., Hosaka, S., Itow, Y., Kamiya, K., Kilmartin, P. M., Kobara, S., Korpela, A., Lin, W., Ling, C. H., Makita, S., Masuda, K., Matsubara, Y., Miyake, N., Muraki, Y., Nagaya, M., Nishimoto, K., Ohnishi, K., Okumura, T., Omori, K., Perrott, Y. C., Rattenbury, N., Saito, To., Skuljan, L., Sullivan, D. J., Suzuki, D., Suzuki, K., Sweatman, W. L., Takino, S., Tristram, P. J., Wada, K., Yock, P. C. M., The MOA Collaboration, Szymański, M. K., Kubiak, M., Pietrzyński, G., Soszyński, I., Poleski, R., Ulaczyk, K., Wyrzykowski, Ł., Kozłowski, S., Pietrukowicz, P., The OGLE Collaboration, Albrow, M. D., Bachelet, E., Batista, V., Bennett, C. S., Bowens-Rubin, R., Brillant, S., Cassan, A., Cole, A., Corrales, E., Coutures, Ch., Dieters, S., Dominis Prester, D., Donatowicz, J., Fouqué, P., Greenhill, J., Kane, S. R., Menzies, J., Sahu, K. C., Wambsganss, J., Williams, A., Zub, M., The PLANET Collaboration, Allan, A., Bramich, D. M., Browne, P., Clay, N., Fraser, S., Horne, K., Kains, N., Mottram, C., Snodgrass, C., Steele, I., Tsapras, Y., The RoboNet Collaboration, Alsubai, K. A., Bozza, V., Burgdorf, M. J., Calchi Novati, S., Dodds, P., Dreizler, S., Finet, F., Gerner, T., Glitrup, M., Grundahl, F., Hardis, S., Harpsøe, K., Hinse, T. C., Hundertmark, M., Jørgensen, U. G., Kerins, E., Liebig, C., Maier, G., Mancini, L., Mathiasen, M., Penny, M. T., Proft, S., Rahvar, S., Ricci, D., Scarpetta, G., Schäfer, S., Schönebeck, F., Skottfelt, Jesper Fælling, Surdej, J., Southworth, J., Zimmer, F., and MiNDSTEp Consortium, The

Subjects
Physics, 010308 nuclear & particles physics, Brown dwarf, FOS: Physical sciences, Astronomy and Astrophysics, gravitational lensing: micro, Astrophysics, Mass ratio, Light curve, Gravitational microlensing, 01 natural sciences, Galaxy: bulge, Galaxy: bulge, gravitational lensing: micro, Einstein radius, law.invention, Lens (optics), Stars, Astrophysics - Solar and Stellar Astrophysics, Settore FIS/05 - Astronomia e Astrofisica, Space and Planetary Science, law, 0103 physical sciences, Surface brightness, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR)
Abstract

We present the analysis of the light curves of 9 high-magnification single-lens gravitational microlensing events with lenses passing over source stars, including OGLE-2004-BLG-254, MOA-2007-BLG-176, MOA-2007-BLG-233/OGLE-2007-BLG-302, MOA-2009-BLG-174, MOA-2010-BLG-436, MOA-2011-BLG-093, MOA-2011-BLG-274, OGLE-2011-BLG-0990/MOA-2011-BLG-300, and OGLE-2011-BLG-1101/MOA-2011-BLG-325. For all events, we measure the linear limb-darkening coefficients of the surface brightness profile of source stars by measuring the deviation of the light curves near the peak affected by the finite-source effect. For 7 events, we measure the Einstein radii and the lens-source relative proper motions. Among them, 5 events are found to have Einstein radii less than 0.2 mas, making the lenses candidates of very low-mass stars or brown dwarfs. For MOA-2011-BLG-274, especially, the small Einstein radius of $\theta_{\rm E}\sim 0.08$ mas combined with the short time scale of $t_{\rm E}\sim 2.7$ days suggests the possibility that the lens is a free-floating planet. For MOA-2009-BLG-174, we measure the lens parallax and thus uniquely determine the physical parameters of the lens. We also find that the measured lens mass of $\sim 0.84\ M_\odot$ is consistent with that of a star blended with the source, suggesting that the blend is likely to be the lens. Although we find planetary signals for none of events, we provide exclusion diagrams showing the confidence levels excluding the existence of a planet as a function of the separation and mass ratio., Comment: 14 pages, 12 figures, 5 tables

Published
2012

21. Characterizing Low-Mass Binaries From Observation of Long Time-scale Caustic-crossing Gravitational Microlensing Events

Author

Shin, I.-G, Han, C., Choi, J.-Y, Udalski, A., Sumi, T., Gould, A., Bozza, V., Dominik, M., Fouque´, P., Horne, K., Szyman´ski, M. K., Kubiak, M., Soszyn´ski, I., Pietrzyn´ski, G., Poleski, R., Ulaczyk, K., Pietrukowicz, P., Kozłowski, S., Skowron, J., Wyrzykowski, Ł., Abe, F., Bennett, D. P., Bond, I. A., Botzler, C. S., Chote, P., Freeman, M., Fukui, A., Furusawa, K., Itow, Y., Kobara, S., Ling, C. H., Masuda, K., Matsubara, Y., Miyake, N., Muraki, Y., Ohmori, K., Ohnishi, K., Rattenbury, N. J., Saito, To, Sullivan, D. J., Suzuki, D., Suzuki, K., Sweatman, W. L., Takino, S., Tristram, P. J., Wada, K., Yock, P. C. M., MOA Collaboration, Bramich, D. M., Snodgrass, C., Steele, I. A., Street, R. A., Tsapras, Y., RoboNet Collaboration, Alsubai, K. A., Browne, P., Burgdorf, M. J., Calchi Novati, S., Dodds, P., Dreizler, S., Fang, X.-S, Grundahl, Frank, Gu, C.-H, Hardis, S., Harpsøe, Kennet Bomann West, Hinse, T. C., Hornstrup, Allan, Hundertmark, M., Jessen-Hansen, Jens, Jørgensen, U. G., Kains, N., Kerins, E., Liebig, C., Lund, M., Lunkkvist, M., Mancini, L., Mathiasen, M., Penny, M. T., Rahvar, S., Ricci, D., Scarpetta, G., Skottfelt, J., Southworth, J., Surdej, J., Tregloan-Reed, J., Wambsganss, J., Wertz, O., Almeida, L. A., Batista, V., Christie, G., DePoy, D. L., Dong, Subo, Gaudi, B. S., Henderson, C., Jablonski, F., Lee, C.-U, McCormick, J., McGregor, D., Moorhouse, D., Natusch, T., Ngan, H., Park, S.-Y., Pogge, R. W., Tan, T.-G, Thornley, G., Yee, J. C., Albrow, M. D., Bachelet, E., Beaulieu, J.-P, Brillant, S., Cassan, A., Cole, A. A., Corrales, E., Coutures, C., Dieters, S., Dominis Prester, D., Donatowicz, J., Greenhill, J., Kubas, D., Marquette, J.-B, Menzies, J. W., Sahu, K. C., and Zub, M.

Subjects
binaries: general, gravitational lensing: micro, 010504 meteorology & atmospheric sciences, Binary number, FOS: Physical sciences, Astrophysics, Gravitational microlensing, 01 natural sciences, Einstein radius, micro [Gravitational lensing], Settore FIS/05 - Astronomia e Astrofisica, 0103 physical sciences, Binary star, binaries: general, gravitational lensing: micro, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), 0105 earth and related environmental sciences, Orbital elements, Physics, general [Binaries], Observational techniques, Astronomy and Astrophysics, Light curve, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Low Mass
Abstract

Despite astrophysical importance of binary star systems, detections are limited to those located in small ranges of separations, distances, and masses and thus it is necessary to use a variety of observational techniques for a complete view of stellar multiplicity across a broad range of physical parameters. In this paper, we report the detections and measurements of 2 binaries discovered from observations of microlensing events MOA-2011-BLG-090 and OGLE-2011-BLG-0417. Determinations of the binary masses are possible by simultaneously measuring the Einstein radius and the lens parallax. The measured masses of the binary components are 0.43 $M_{\odot}$ and 0.39 $M_{\odot}$ for MOA-2011-BLG-090 and 0.57 $M_{\odot}$ and 0.17 $M_{\odot}$ for OGLE-2011-BLG-0417 and thus both lens components of MOA-2011-BLG-090 and one component of OGLE-2011-BLG-0417 are M dwarfs, demonstrating the usefulness of microlensing in detecting binaries composed of low-mass components. From modeling of the light curves considering full Keplerian motion of the lens, we also measure the orbital parameters of the binaries. The blended light of OGLE-2011-BLG-0417 comes very likely from the lens itself, making it possible to check the microlensing orbital solution by follow-up radial-velocity observation. For both events, the caustic-crossing parts of the light curves, which are critical for determining the physical lens parameters, were resolved by high-cadence survey observations and thus it is expected that the number of microlensing binaries with measured physical parameters will increase in the future., Comment: 8 pages, 5 figures, 4 tables

Published
2012

22. Microlensing Binaries Discovered through High-Magnification Channel

Author

Shin, I.-G., Choi, J.-Y., Park, S.-Y., Han, C., Gould, A., Sumi, T., Udalski, A., Beaulieu, J.-P., Dominik, M., Allen, W., Bos, M., Christie, G. W., Depoy, D. L., Dong, S., Drummond, J., Gal-Yam, A., Gaudi, B. S., Hung, L.-W., Janczak, J., Kaspi, S., Lee, C.-U., Mallia, F., Maoz, D., Maury, A., McCormick, J., Monard, L. A. G., Moorhouse, D., Muñoz, J. A., Natusch, T., Nelson, C., Park, B.-G., Pogge, R. W., Polishook, D., Shvartzvald, Y., Shporer, A., Thornley, G., Yee, J. C., μFUN Collaboration, Abe, F., Bennett, D. P., Bond, I. A., Botzler, C. S., Fukui, A., Furusawa, K., Hayashi, F., Hearnshaw, J. B., Hosaka, S., Itow, Y., Kamiya, K., Kilmartin, P. M., Kobara, S., Korpela, A., Lin, W., Ling, C. H., Makita, S., Masuda, K., Matsubara, Y., Miyake, N., Muraki, Y., Nagaya, M., Nishimoto, K., Ohnishi, K., Okumura, T., Omori, K., Perrott, Y. C., Rattenbury, N., Saito, To., Skuljan, L., Sullivan, D. J., Suzuki, D., Sweatman, W. L., Tristram, P. J., Wada, K., Yock, P. C. M., MOA Collaboration, Szymański, M. K., Kubiak, M., Pietrzyński, G., Soszyński, I., Poleski, R., Ulaczyk, K., Wyrzykowski, Ł., Kozłowski, S., Pietrukowicz, P., OGLE Collaboration, Albrow, M. D., Batista, V., Bramich, D. M., Brillant, S., Caldwell, J. A. R., Calitz, J. J., Cassan, A., Cole, A., Cook, K. H., Corrales, E., Coutures, Ch., Dieters, S., Dominis Prester, D., Donatowicz, J., Fouqué, P., Greenhill, J., Hoffman, M., Jørgensen, U. G., Kane, S. R., Kubas, D., Marquette, J.-B., Martin, R., Meintjes, P., Menzies, J., Pollard, K. R., Sahu, K. C., Wambsganss, J., Williams, A., Vinter, Christian, Zub, M., PLANET Collaboration, Allan, A., Browne, P., Horne, K., Snodgrass, C., Steele, I., Street, R., Tsapras, Y., RoboNet Collaboration, Alsubai, K. A., Bozza, V., Burgdorf, M. J., Calchi Novati, S., Dodds, P., Dreizler, S., Finet, F., Gerner, T., Glitrup, M., Grundahl, F., Hardis, S., Harpsøe, Kennet Bomann West, Hessman, F. V., Hinse, T. C., Hundertmark, M., Kains, N., Kerins, E., Liebig, C., Maier, G., Mancini, L., Mathiasen, M., Penny, M. T., Proft, S., Rahvar, S., Ricci, D., Scarpetta, G., Schäfer, S., Schönebeck, F., Skottfelt, Jesper Fælling, Surdej, J., Southworth, J., Zimmer, F., and MiNDSTEp Consortium

Subjects
binaries: general, gravitational lensing: micro, Binary number, FOS: Physical sciences, Astrophysics, Gravitational microlensing, 01 natural sciences, law.invention, Settore FIS/05 - Astronomia e Astrofisica, Planet, law, 0103 physical sciences, binaries: general, gravitational lensing: micro, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Physics, 010308 nuclear & particles physics, Astronomy and Astrophysics, Mass ratio, Light curve, 3. Good health, Lens (optics), Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Astrophysics::Earth and Planetary Astrophysics, Degeneracy (mathematics), Event (particle physics)
Abstract

Microlensing can provide a useful tool to probe binary distributions down to low-mass limits of binary companions. In this paper, we analyze the light curves of 8 binary lensing events detected through the channel of high-magnification events during the seasons from 2007 to 2010. The perturbations, which are confined near the peak of the light curves, can be easily distinguished from the central perturbations caused by planets. However, the degeneracy between close and wide binary solutions cannot be resolved with a $3\sigma$ confidence level for 3 events, implying that the degeneracy would be an important obstacle in studying binary distributions. The dependence of the degeneracy on the lensing parameters is consistent with a theoretic prediction that the degeneracy becomes severe as the binary separation and the mass ratio deviate from the values of resonant caustics. The measured mass ratio of the event OGLE-2008-BLG-510/MOA-2008-BLG-369 is $q\sim 0.1$, making the companion of the lens a strong brown-dwarf candidate., Comment: 10 figures, 6 tables, 26 pages

Published
2011

23. A sub-Saturn mass planet, MOA-2009-BLG-319Lb

Author

Miyake, N., Sumi, T., Dong, Subo, Street, R., Mancini, L., Gould, A., Bennett, D. P., Tsapras, Y., Yee, J. C., Albrow, M. D., Bond, I. A., Fouque, P., Browne, P., Han, C., Snodgrass, C., Finet, F., Furusawa, K., Harpsoe, K., Allen, W., Hundertmark, M., Freeman, M., Suzuki, D., Abe, F., Botzler, C. S., Douchin, D., Fukui, A., Hayashi, F., Hearnshaw, J. B., Hosaka, S., Itow, Y., Kamiya, K., Kilmartin, P. M., Korpela, A., Lin, W., Ling, C. H., Makita, S., Masuda, K., Matsubara, Y., Muraki, Y., Nagayama, T., Nishimoto, K., Ohnishi, K., Perrott, Y. C., Rattenbury, N., Saito, To., Skuljan, L., Sullivan, D. J., Sweatman, W. L., Tristram, P. J., Wada, K., Yock, P. C. M., Collaboration, The MOA, Bolt, G., Bos, M., Christie, G. W., DePoy, D. L., Drummond, J., Gal-Yam, A., Gaudi, B. S., Gorbikov, E., Higgins, D., Janczak, K. -H. Hwang J., Kaspi, S., Lee, C. -U., Koo, J. -R., lowski, S. Koz, Lee, Y., Mallia, F., Maury, A., Maoz, D., McCormick, J., Monard, L. A. G., Moorhouse, D., Mu~noz, J. A., Natusch, T., Ofek, E. O., Pogge, R. W., Polishook, D., Santallo, R., Shporer, A., Spector, O., Thornley, G., Collaboration, The Micro FUN, Allan, A., Bramich, D. M., Horne, K., Kains, N., Steele, I., Collaboration, The RoboNet, Bozza, V., Burgdorf, M. J., Novati, S. Calchi, Dominik, M., Dreizler, S., Glitrup, M., Hessman, F. V., Hinse, T. C., Jorgensen, U. G., Liebig, C., Maier, G., Mathiasen, M., Rahvar, S., Ricci, D., Scarpetta, G., Skottfelt, J., Southworth, J., Surdej, J., Wambsganss, J., Zimmer, F., Consortium, The MiNDSTEp, Batista, V., Beaulieu, J. P., Brillant, S., Cassan, A., Cole, A., Corrales, E., Coutures, Ch., Dieters, S., Greenhill, J., Kubas, D., Menzies, J., and Collaboration, The PLANET

Subjects
Physics, Earth and Planetary Astrophysics (astro-ph.EP), FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Planetary system, Mass ratio, Gravitational microlensing, Light curve, 01 natural sciences, Einstein radius, Settore FIS/05 - Astronomia e Astrofisica, Space and Planetary Science, Planet, Saturn, 0103 physical sciences, Astrophysics::Earth and Planetary Astrophysics, 010306 general physics, 010303 astronomy & astrophysics, Planetary mass, Astrophysics::Galaxy Astrophysics, Astrophysics - Earth and Planetary Astrophysics
Abstract

We report the gravitational microlensing discovery of a sub-Saturn mass planet, MOA-2009-BLG-319Lb, orbiting a K or M-dwarf star in the inner Galactic disk or Galactic bulge. The high cadence observations of the MOA-II survey discovered this microlensing event and enabled its identification as a high magnification event approximately 24 hours prior to peak magnification. As a result, the planetary signal at the peak of this light curve was observed by 20 different telescopes, which is the largest number of telescopes to contribute to a planetary discovery to date. The microlensing model for this event indicates a planet-star mass ratio of q = (3.95 +/- 0.02) x 10^{-4} and a separation of d = 0.97537 +/- 0.00007 in units of the Einstein radius. A Bayesian analysis based on the measured Einstein radius crossing time, t_E, and angular Einstein radius, \theta_E, along with a standard Galactic model indicates a host star mass of M_L = 0.38^{+0.34}_{-0.18} M_{Sun} and a planet mass of M_p = 50^{+44}_{-24} M_{Earth}, which is half the mass of Saturn. This analysis also yields a planet-star three-dimensional separation of a = 2.4^{+1.2}_{-0.6} AU and a distance to the planetary system of D_L = 6.1^{+1.1}_{-1.2} kpc. This separation is ~ 2 times the distance of the snow line, a separation similar to most of the other planets discovered by microlensing., Comment: accepted to ApJ, 28 pages, 6 figures, 3 tables

Published
2011

24. MOA-2009-BLG-387Lb: A massive planet orbiting an M dwarf

Author

Batista, V., Gould, A., Dieters, S., Dong, S., Bond, I., Beaulieu, J. P., Maoz, D., Monard, B., Christie, G. W., Mccormick, J., Albrow, M. D., Horne, K., Tsapras, Y., Burgdorf, M. J., Calchi Novati, S., Skottfelt, J., Caldwell, J., Kozłowski, S., Kubas, D., Gaudi, B. S., Han, C., Bennett, D. P., An, J., Abe, F., Botzler, C. S., Douchin, D., Freeman, M., Fukui, A., Furusawa, K., Hearnshaw, J. B., Hosaka, S., Itow, Y., Kamiya, K., Kilmartin, P. M., Korpela, A., Lin, W., Ling, C. H., Makita, B. S., Masuda, K., Matsubara, Y., Miyake, N., Muraki, Y., Nagaya, M., Nishimoto, K., Ohnishi, K., Okumura, T., Perrott, Y. C., Rattenbury, N., Saito, T. o., Sullivan, D. J., Sumi, T., Sweatman, W. L., Tristram, P. J., von Seggern, E., Yock, P. C. M., Brillant, S., Calitz, J. J., Cassan, A., Cole, A., Cook, K., Coutures, C., Dominis Prester, D., Donatowicz, J., Greenhill, J., Hoffman, M., Jablonski, F., Kane, S. R., Kains, N., Marquette, J. B., Martin, R., Martioli, E., Meintjes, P., Menzies, J., Pedretti, E., Pollard, K., Sahu, K. C., Vinter, C., Wambsganss, J., Watson, R., Williams, A., Zub, M., Allen, W., Bolt, G., Bos, M., Depoy, D. L., Drummond, J., Eastman, J. D., Gal Yam, A., Gorbikov, E., Higgins, D., Janczak, J., Kaspi, S., Lee, C. U., Mallia, F., Maury, A., Monard, L. A. G., Moorhouse, D., Morgan, N., Natusch, T., Ofek, E. O., Park, B. G., Pogge, R. W., Polishook, D., Santallo, R., Shporer, A., Spector, O., Thornley, G., Yee, J. C., Bozza, Valerio, Browne, P., Dominik, M., Dreizler, S., Finet, F., Glitrup, M., Grundahl, F., Harpsøe, K., Hessman, F. V., Hinse, T. C., Hundertmark, M., Jørgensen, U. G., Liebig, C., Maier, G., Mancini, L., Mathiasen, M., Rahvar, S., Ricci, D., Scarpetta, Gaetano, Southworth, J., Surdej, J., Zimmer, F., Allan, A., Bramich, D. M., Snodgrass, C., Steele, I. A., and Street, R. A.

Subjects
Physics, Earth and Planetary Astrophysics (astro-ph.EP), 010308 nuclear & particles physics, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Mass ratio, Gravitational microlensing, 01 natural sciences, Einstein radius, Jupiter, Settore FIS/05 - Astronomia e Astrofisica, 13. Climate action, Space and Planetary Science, Planet, 0103 physical sciences, Orbital motion, High Energy Physics::Experiment, gravitational lensing, micro methods, data analysis, planets, satellites, detection, methods, numerical, instrumentation, adaptive optics, photometers, Astrophysics::Earth and Planetary Astrophysics, 010303 astronomy & astrophysics, Planetary mass, Astrophysics::Galaxy Astrophysics, Astrophysics - Earth and Planetary Astrophysics
Abstract

We report the discovery of a planet with a high planet-to-star mass ratio in the microlensing event MOA-2009-BLG-387, which exhibited pronounced deviations over a 12-day interval, one of the longest for any planetary event. The host is an M dwarf, with a mass in the range 0.07 M_sun < M_host < 0.49M_sun at 90% confidence. The planet-star mass ratio q = 0.0132 +- 0.003 has been measured extremely well, so at the best-estimated host mass, the planet mass is m_p = 2.6 Jupiter masses for the median host mass, M = 0.19 M_sun. The host mass is determined from two "higher order" microlensing parameters. One of these, the angular Einstein radius ��_E = 0.31 +- 0.03 mas, is very well measured, but the other (the microlens parallax ��_E, which is due to the Earth's orbital motion) is highly degenate with the orbital motion of the planet. We statistically resolve the degeneracy between Earth and planet orbital effects by imposing priors from a Galactic model that specifies the positions and velocities of lenses and sources and a Kepler model of orbits. The 90% confidence intervals for the distance, semi-major axis, and period of the planet are 3.5 kpc < D_L < 7.9 kpc, 1.1 AU < a < 2.7AU, and 3.8 yr < P < 7.6 yr, respectively., 20 pages including 8 figures. A&A 529 102 (2011)

Published
2011
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25. OGLE-2009-BLG-092/MOA-2009-BLG-137: A Dramatic Repeating Event with the Second Perturbation Predicted by Real-time Analysis

Author

Ryu, Y. H., Han, C., Hwang, K. H., Street, R., Udalski, A., Sumi, T., Fukui, A., Beaulieu, J. P., Gould, A., Dominik, M., Abe, F., Bennett, D. P., Bond, I. A., Botzler, C. S., Furusawa, K., Hayashi, F., Hearnshaw, J. B., Hosaka, S., Itow, Y., Kamiya, K., Kilmartin, P. M., Korpela, A., Lin, W., Ling, C. H., Makita, S., Masuda, K., Matsubara, Y., Miyake, N., Muraki, Y., Nishimoto, K., Ohnishi, K., Perrott, Y. C., Rattenbury, N., Saito, T. o., Skuljan, L., Sullivan, D. J., Suzuki, D., Sweatman, W. L., Tristram, P. J., Wada, K., Yock, P. C. M., Szymański, M. K., Kubiak, M., Pietrzyński, G., Poleski, R., Soszyński, I., Szewczyk, O., Wyrzykowski, Ł., Ulaczyk, K., Bos, M., Christie, G. W., Depoy, D. L., Gal Yam, A., Gaudi, B. S., Kaspi, S., Lee, C. U., Maoz, D., Mccormick, J., Monard, B., Moorhouse, D., Pogge, R. W., Polishook, D., Shvartzvald, Y., Shporer, A., Thornley, G., Yee, J. C., Albrow, M. D., Batista, V., Brillant, S., Cassan, A., Cole, A., Corrales, E., Coutures, C. h., Dieters, S., Fouque, P., Greenhill, J., Menzies, J., Allan, A., Bramich, D. M., Browne, P., Horne, K., Kains, N., Snodgrass46, C., Steele, I., Tsapras, Y., Bozza, Valerio, Burgdorf, M. J., CALCHI NOVATI, Sebastiano, Dreizler, S., Finet, F., Glitrup, M., Grundahl, F., Harpsøe, K., Hessman, F. V., Hinse, T. C., Hundertmark, M., Jørgensen, U. G., Liebig, C., Maier, G., Mancini, Luigi, Mathiasen, M., Rahvar, S., Ricci, D., Scarpetta, Gaetano, Skottfelt, J., Surdej, J., Southworth, J., Wambsganss, J., and Zimmer, F.

Subjects
Physics, 010504 meteorology & atmospheric sciences, FOS: Physical sciences, Binary number, Perturbation (astronomy), Astronomy and Astrophysics, Astrophysics, Light curve, Gravitational microlensing, 01 natural sciences, Stars, Settore FIS/05 - Astronomia e Astrofisica, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Bulge, 0103 physical sciences, Orbital motion, Real time analysis, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), 0105 earth and related environmental sciences
Abstract

We report the result of the analysis of a dramatic repeating gravitational microlensing event OGLE-2009-BLG-092/MOA-2009-BLG-137, for which the light curve is characterized by two distinct peaks with perturbations near both peaks. We find that the event is produced by the passage of the source trajectory over the central perturbation regions associated with the individual components of a wide-separation binary. The event is special in the sense that the second perturbation, occurring $\sim 100$ days after the first, was predicted by the real-time analysis conducted after the first peak, demonstrating that real-time modeling can be routinely done for binary and planetary events. With the data obtained from follow-up observations covering the second peak, we are able to uniquely determine the physical parameters of the lens system. We find that the event occurred on a bulge clump giant and it was produced by a binary lens composed of a K and M-type main-sequence stars. The estimated masses of the binary components are $M_1=0.69 \pm 0.11\ M_\odot$ and $M_2=0.36\pm 0.06\ M_\odot$, respectively, and they are separated in projection by $r_\perp=10.9\pm 1.3\ {\rm AU}$. The measured distance to the lens is $D_{\rm L}=5.6 \pm 0.7\ {\rm kpc}$. We also detect the orbital motion of the lens system., 18 pages, 5 figures, 1 table

Published
2010

26. A Cold Neptune-Mass Planet OGLE-2007-BLG-368Lb: Cold Neptunes Are Common

Author

Sumi, T., Bennett, D. P., Bond, I. A., Udalski, A., Batista, V., Dominik, M., Fouqu��, P., Kubas, D., Gould, A., Macintosh, B., Cook, K., Dong, S., Skuljan, L., Cassan, A., Collaboration, The MOA, Abe, F., Botzler, C. S., Fukui, A., Furusawa, K., Hearnshaw, J. B., Itow, Y., Kamiya, K., Kilmartin, P. M., Korpela, A., Lin, W., Ling, C. H., Masuda, K., Matsubara, Y., Miyake, N., Muraki, Y., Nagaya, M., Nagayama, T., Ohnishi, K., Okumura, T., Perrott, Y. C., Rattenbury, N., Saito, To., Sako, T., Sullivan, D. J., Sweatman, W. L., Yock, P. C. M., Collaboration, The PLANET, Beaulieu, J. P., Cole, A., Coutures, Ch., Duran, M. F., Greenhill, J., Jablonski, F., Marboeuf, U., Martioli, E., Pedretti, E., Pejcha, O., Rojo, P., Albrow, M. D., Brillant, S., Bode, M., Bramich, D. M., Burgdorf, M. J., Caldwell, J. A. R., Calitz, H., Corrales, E., Dieters, S., Prester, D. Dominis, Donatowicz, J., Hill, K., Hoffman, M., Horne, K., J, U. G., Kains, N., Kane, S., Marquette, J. B., Martin, R., Meintjes, P., Menzies, J., Pollard, K. R., Sahu, K. C., Snodgrass, C., Steele, I., Street, R., Tsapras, Y., Wambsganss, J., Williams, A., Zub, M., Collaboration, The OGLE, Szyma, M. K., Kubiak, M., Pietrzy, G., Soszy, I., Szewczyk, O., Ulaczyk, K., Collaboration, The microFUN, Allen, W., Christie, G. W., DePoy, D. L., Gaudi, B. S., Han, C., Janczak, J., Lee, C. -U., McCormick, J., Mallia, F., Monard, B., Natusch, T., Park, B. -G., Pogge, R. W., Santallo, R., Solar-Terrestrial Environment Laboratory [Nagoya] (STEL), Nagoya University, University of Notre Dame [Indiana] (UND), Massey University, Astronomical Observatory [Warsaw], Faculty of Physics [Warsaw] (FUW), University of Warsaw (UW)-University of Warsaw (UW), Institut d'Astrophysique de Paris (IAP), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), SUPA School of Physics and Astronomy [University of St Andrews], University of St Andrews [Scotland]-Scottish Universities Physics Alliance (SUPA), Laboratoire Astrophysique de Toulouse-Tarbes (LATT), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), European Southern Observatory [Santiago] (ESO), European Southern Observatory (ESO), Department of Astronomy (Ohio State University), Ohio State University [Columbus] (OSU), Astronomische Rechen-Institut [Heidelberg] (ARI), Zentrum für Astronomie der Universität Heidelberg (ZAH), Universität Heidelberg [Heidelberg] = Heidelberg University-Universität Heidelberg [Heidelberg] = Heidelberg University, Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Instituto Nacional de Pesquisas Espaciais (INPE), Ministério da Ciência, Tecnologia e Inovação, Univers, Transport, Interfaces, Nanostructures, Atmosphère et environnement, Molécules (UMR 6213) (UTINAM), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Franche-Comté (UFC), and Université Bourgogne Franche-Comté [COMUE] (UBFC)-Université Bourgogne Franche-Comté [COMUE] (UBFC)

Subjects
Physics, gravitational lensing: micro, planetary systems, Earth and Planetary Astrophysics (astro-ph.EP), Stellar mass, [PHYS.ASTR.EP]Physics [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Gas giant, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Mass ratio, Light curve, Gravitational microlensing, 01 natural sciences, Exoplanet, Space and Planetary Science, Neptune, Planet, 0103 physical sciences, 010306 general physics, 010303 astronomy & astrophysics, ComputingMilieux_MISCELLANEOUS, Astrophysics - Earth and Planetary Astrophysics
Abstract

We present the discovery of a Neptune-mass planet OGLE-2007-BLG-368Lb with a planet-star mass ratio of q=[9.5 +/- 2.1] x 10^{-5} via gravitational microlensing. The planetary deviation was detected in real-time thanks to the high cadence of the MOA survey, real-time light curve monitoring and intensive follow-up observations. A Bayesian analysis returns the stellar mass and distance at M_l = 0.64_{-0.26}^{+0.21} M_\sun and D_l = 5.9_{-1.4}^{+0.9} kpc, respectively, so the mass and separation of the planet are M_p = 20_{-8}^{+7} M_\oplus and a = 3.3_{-0.8}^{+1.4} AU, respectively. This discovery adds another cold Neptune-mass planet to the planetary sample discovered by microlensing, which now comprise four cold Neptune/Super-Earths, five gas giant planets, and another sub-Saturn mass planet whose nature is unclear. The discovery of these ten cold exoplanets by the microlensing method implies that the mass ratio function of cold exoplanets scales as dN_{\rm pl}/d\log q \propto q^{-0.7 +/- 0.2} with a 95% confidence level upper limit of n < -0.35 (where dN_{\rm pl}/d\log q \propto q^n). As microlensing is most sensitive to planets beyond the snow-line, this implies that Neptune-mass planets are at least three times more common than Jupiters in this region at the 95% confidence level., 39 pages, 10 figures, accepted for publication in ApJ

Published
2009
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27. A new activity phase of the blazar 3C 454.3. Multifrequency observations by the WEBT and XMM-Newton in 2007-2008

Author

Raiteri, C. M., Villata, M, Larionov, V. M., Gurwell, M. A., Chen, W. P., Kurtanidze, O. M., Aller, M. F., Böttcher, M, Calcidese, P, Hroch, F, Lähteenmäki, A, Lee, C. U., Nilsson, K, Ohlert, J, Papadakis, I. E., Agudo, I, Aller, H. D., Angelakis, E, Arkharov, A. A., Bach, U, Bachev, R, Berdyugin, A, Buemi, C. S., Carosati, D, Charlot, P, Chatzopoulos, E, Forné, E, Frasca, A, Fuhrmann, L, Gómez, J. L., Gupta, A. C., HAGEN THORN, V. A., Hsiao, W. S., Jordan, B, Jorstad, S. G., Konstantinova, T. S., Kopatskaya, E. N., Krichbaum, T. P., Lanteri, L, Larionova, L. V., Latev, G, LE CAMPION, J. F., Leto, P, Lin, H. C., Marchili, N, Marilli, E, Marscher, A. P., Mcbreen, B, Mihov, B, Nesci, R, Nicastro, F, Nikolashvili, M. G., Novak, R, Ovcharov, E, Pian, E, Principe, D, Pursimo, T, Ragozzine, B, Ros, J. A., Sadun, A. C., Sagar, R, Semkov, E, Smart, R. L., Smith, N, Strigachev, A, Takalo, L. O., Tavani, M, Tornikoski, M, Trigilio, Corrado, Uckert, K, Umana, G, Valcheva, A, Vercellone, S, Volvach, A, Wiesemeyer, H., INAF - Osservatorio Astrofisico di Torino (OATo), Istituto Nazionale di Astrofisica (INAF), Shanghai Institute of Ceramics, Chinese Academy of Science (CAS), Laboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux (L3AB), Université Sciences et Technologies - Bordeaux 1-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Observatoire aquitain des sciences de l'univers (OASU), Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), and Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Photon, [PHYS.ASTR.EP]Physics [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Astrophysics::High Energy Astrophysical Phenomena, galaxies: active, [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], FOS: Physical sciences, Flux, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Radiation, 01 natural sciences, Spectral line, law.invention, [PHYS.ASTR.CO]Physics [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO], law, 0103 physical sciences, galaxies: quasars: individual: 3C 454.3, Emission spectrum, Blazar, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Physics, 010308 nuclear & particles physics, Astrophysics (astro-ph), Astronomy and Astrophysics, galaxies: jets, Light curve, Synchrotron, galaxies: quasars: general, 13. Climate action, Space and Planetary Science
Abstract

We present and analyse the WEBT multifrequency observations of 3C 454.3 in the 2007-2008 observing season, including XMM-Newton observations and near-IR spectroscopic monitoring, and compare the recent emission behaviour with the past one. In the optical band we observed a multi-peak outburst in July-August 2007, and other faster events in November 2007 - February 2008. During these outburst phases, several episodes of intranight variability were detected. A mm outburst was observed starting from mid 2007, whose rising phase was contemporaneous to the optical brightening. A slower flux increase also affected the higher radio frequencies, the flux enhancement disappearing below 8 GHz. The analysis of the optical-radio correlation and time delays, as well as the behaviour of the mm light curve, confirm our previous predictions, suggesting that changes in the jet orientation likely occurred in the last few years. The historical multiwavelength behaviour indicates that a significant variation in the viewing angle may have happened around year 2000. Colour analysis reveals a complex spectral behaviour, which is due to the interplay of different emission components. All the near-IR spectra show a prominent Halpha emission line, whose flux appears nearly constant. The analysis of the XMM-Newton data indicates a correlation between the UV excess and the soft-X-ray excess, which may represent the head and the tail of the big blue bump, respectively. The X-ray flux correlates with the optical flux, suggesting that in the inverse-Compton process either the seed photons are synchrotron photons at IR-optical frequencies or the relativistic electrons are those that produce the optical synchrotron emission. The X-ray radiation would thus be produced in the jet region from where the IR-optical emission comes., Comment: 10 pages, 12 figures (7 included in the text, 5 in GIF format), accepted for publication in A&A

Published
2008

28. A NEW TYPE OF AMBIGUITY IN THE PLANET AND BINARY INTERPRETATIONS OF CENTRAL PERTURBATIONS OF HIGH-MAGNIFICATION GRAVITATIONAL MICROLENSING EVENTS

Author

Choi, J.-Y, Shin, I.-G, Han, C., Udalski, A., Sumi, T., Gould, A., Bozza, V., Dominik, M., Fouque´, P., Horne, K., Szyman´ski, M. K., Kubiak, M., Soszyn´ski, I., Pietrzyn´ski, G., Poleski, R., Ulaczyk, K., Pietrukowicz, P., Kozłowski, S., Skowron, J., Wyrzykowski, Ł., OGLE Collaboration, Abe, F., Bennett, D. P., Bond, I. A., Botzler, C. S., Chote, P., Freeman, M., Fukui, A., Furusawa, K., Itow, Y., Kobara, S., Ling, C. H., Masuda, K., Matsubara, Y., Miyake, N., Muraki, Y., Ohmori, K., Ohnishi, K., Rattenbury, N. J., Saito, To, Sullivan, D. J., Suzuki, D., Suzuki, K., Sweatman, W. L., Takino, S., Tristram, P. J., Wada, K., Yock, P. C. M., MOA Collaboration, Bramich, D. M., Snodgrass, C., Steele, I. A., Street, R. A., Tsapras, Y., RoboNet Collaboration, Alsubai, K. A., Browne, P., Burgdorf, M. J., Calchi Novati, S., Dodds, P., Dreizler, S., Fang, X.-S, Grundahl, F., Gu, C.-H, Hardis, S., Harpsøe, K., Hinse, T. C., Hornstrup, Allan, Hundertmark, M., Jessen-Hansen, J., Jørgensen, U. G., Kains, N., Kerins, E., Liebig, C., Lund, M., Lunkkvist, M., Mancini, L., Mathiasen, M., Penny, M. T., Rahvar, S., Ricci, D., Scarpetta, G., Skottfelt, J., Southworth, J., Surdej, J., Tregloan-Reed, J., Wambsganss, J., Wertz, O., Almeida, L. A., Batista, V., Christie, G., DePoy, D. L., Dong, Subo, Gaudi, B. S., Henderson, C., Jablonski, F., Lee, C.-U, McCormick, J., McGregor, D., Moorhouse, D., Natusch, T., Ngan, H., Pogge, R. W., Tan, T.-G, Thornley, G., Yee, J. C., Albrow, M. D., Bachelet, E., Beaulieu, J.-P, Brillant, S., Cassan, A., Cole, A. A., Corrales, E., Coutures, C., Dieters, S., Dominis Prester, D., Donatowicz, J., Greenhill, J., Kubas, D., Marquette, J.-B, Menzies, J. W., Sahu, K. C., and Zub, M.

Subjects
media_common.quotation_subject, FOS: Physical sciences, Binary number, Perturbation (astronomy), gravitational lensing: micro, Astrophysics, Gravitational microlensing, 01 natural sciences, Galaxy: bulge, Settore FIS/05 - Astronomia e Astrofisica, Planet, 0103 physical sciences, 010306 general physics, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), media_common, Earth and Planetary Astrophysics (astro-ph.EP), Physics, Binary Independence Model, Astronomy and Astrophysics, Ambiguity, Light curve, Galaxy: bulge, gravitational lensing: micro, Astrophysics - Solar and Stellar Astrophysics, 13. Climate action, Space and Planetary Science, Astrophysics::Earth and Planetary Astrophysics, Caustic (optics), Astrophysics - Earth and Planetary Astrophysics
Abstract

High-magnification microlensing events provide an important channel to detect planets. Perturbations near the peak of a high-magnification event can be produced either by a planet or a binary companion. It is known that central perturbations induced by both types of companions can be generally distinguished due to the basically different magnification pattern around caustics. In this paper, we present a case of central perturbations for which it is difficult to distinguish the planetary and binary interpretations. The peak of a lensing light curve affected by this perturbation appears to be blunt and flat. For a planetary case, this perturbation occurs when the source trajectory passes the negative perturbation region behind the back end of an arrowhead-shaped central caustic. For a binary case, a similar perturbation occurs for a source trajectory passing through the negative perturbation region between two cusps of an astroid-shaped caustic. We demonstrate the degeneracy for 2 high-magnification events of OGLE-2011-BLG-0526 and OGLE-2011-BLG-0950/MOA-2011-BLG-336. For OGLE-2011-BLG-0526, the $\chi^2$ difference between the planetary and binary model is $\sim$ 3, implying that the degeneracy is very severe. For OGLE-2011-BLG-0950/MOA-2011-BLG-336, the stellar binary model is formally excluded with $\Delta \chi^2 \sim$ 105 and the planetary model is preferred. However, it is difficult to claim a planet discovery because systematic residuals of data from the planetary model are larger than the difference between the planetary and binary models. Considering that 2 events observed during a single season suffer from such a degeneracy, it is expected that central perturbations experiencing this type of degeneracy is common., Comment: 8 pages, 8 figures

Published
2012

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