Showing papers by "B. S. Gaudi published in 2015"
TL;DR: The OGLE-2005-BLG-169Lb planetary system is located toward the Galactic bulge at a distance of 4.4$ kpc and the projected star-planet separation is 3.3$ AU as discussed by the authors.
Abstract: We present Hubble Space Telescope (HST) Wide Field Camera 3 (WFC3) observations of the source and lens stars for planetary microlensing event OGLE-2005-BLG-169, which confirm the relative proper motion prediction due to the planetary light curve signal observed for this event. This (and the companion Keck result) provide the first confirmation of a planetary microlensing signal, for which the deviation was only 2%. The follow-up observations determine the flux of the planetary host star in multiple passbands and remove light curve model ambiguity caused by sparse sampling of part of the light curve. This leads to a precise determination of the properties of the OGLE-2005-BLG-169Lb planetary system. Combining the constraints from the microlensing light curve with the photometry and astrometry of the HST/WFC3 data, we find star and planet masses of ${M}_{*}=0.69\pm 0.02{M}_{\odot }$ and ${m}_{{\rm{p}}}=14.1\pm 0.9{M}_{\oplus }$. The planetary microlens system is located toward the Galactic bulge at a distance of ${D}_{L}=4.1\pm 0.4$ kpc and the projected star–planet separation is ${a}_{\perp }=3.5\pm 0.3$ AU, corresponding to a semimajor axis of $a={4.0}_{-0.6}^{+2.2}$ AU.
158 citations
TL;DR: In this article, the detection of a Cold Neptune m_planet=21+/-2M orbiting a 0.38MSol M dwarf lying 2.5-3.3 kpc toward the Galactic center as part of a campaign combining ground-based and Spitzer observations was reported.
Abstract: We report the detection of a Cold Neptune m_planet=21+/-2MEarth orbiting a 0.38MSol M dwarf lying 2.5-3.3 kpc toward the Galactic center as part of a campaign combining ground-based and Spitzer observations to measure the Galactic distribution of planets. This is the first time that the complex real-time protocols described by Yee et al. (2015), which aim to maximize planet sensitivity while maintaining sample integrity, have been carried out in practice. Multiple survey and follow-up teams successfully combined their efforts within the framework of these protocols to detect this planet. This is the second planet in the Spitzer Galactic distribution sample. Both are in the near-to-mid disk and clearly not in the Galactic bulge.
97 citations
TL;DR: In this paper, the first space-based microlens parallax measurement of an isolated star is presented, based on the striking differences in the lightcurve as seen from Earth and from Spitzer (~ 1 AU to the west).
Abstract: We present the first space-based microlens parallax measurement of an isolated star. From the striking differences in the lightcurve as seen from Earth and from Spitzer (~ 1 AU to the west), we infer a projected velocity v_(hel) ~ 250kms^(-1), which strongly favors a lens in the Galactic Disk with mass M = 0.23 ± 0.07 M_☉ and distance D_L =3.1 ± 0.4 kpc. An ensemble of such measurements drawn from our ongoing program could be used to measure the single-lens mass function including dark objects, and also is necessary for measuring the Galactic distribution of planets since the ensemble reflects the underlying Galactic distribution of microlenses. We study the application of the many ideas to break the four-fold degeneracy first predicted by Refsdal 50 years ago. We find that this degeneracy is clearly broken, but by two unanticipated mechanisms: a weak constraint on the orbital parallax from the ground-based data and a definitive measurement of the source proper motion.
90 citations
Ohio State University1, Osaka University2, University of Notre Dame3, Massey University4, Chungbuk National University5, Institut d'Astrophysique de Paris6, University of Warsaw7, Las Cumbres Observatory Global Telescope Network8, Queen Mary University of London9, Heidelberg University10, University of Copenhagen11, Nagoya University12, University of Auckland13, University of British Columbia14, College of Industrial Technology15, Victoria University of Wellington16, Kyoto Sangyo University17, Texas A&M University18, Peking University19, Korea Astronomy and Space Science Institute20, Auckland University of Technology21, Harvard University22, Qatar Foundation23, University of St Andrews24, Russian Academy of Sciences25, European Southern Observatory26, Max Planck Society27, Liverpool John Moores University28
TL;DR: The OGLE project has received funding from the National Science Centre, Poland, grant MAESTRO 2014/14/A/ST9/00121 to A.S. as discussed by the authors.
Abstract: A.F. was supported by the Astrobiology Project of the Center for Novel Science Initiatives (CNSI), National Institutes of Natural Sciences (NINS; Grant Number AB261005). T.S. acknowledges the financial support from the JSPS, JSPS23103002, JSPS24253004, and JSPS26247023. The MOA project is supported by grants JSPS25103508 and 23340064. NJR is a Royal Society of New Zealand Rutherford Discovery Fellow. Work by C.H. was supported by Creative Research Initiative Program (2009-0081561) of National Research Foundation of Korea. S.D. is supported by "the Strategic Priority Research Program—The Emergence of Cosmological Structures" of the Chinese Academy of Sciences (grant No. 09000000). The OGLE project has received funding from the National Science Centre, Poland, grant MAESTRO 2014/14/A/ST9/00121 to A.U. C.S. received funding from the European Union Seventh Framework Programme (FP7/2007–2013) under grant agreement No. 268421. K.A., D.M.B., M.D., K.H., M.H., C.L., C.S., R.A.S., and Y.T. would like to thank the Qatar Foundation for support from QNRF grant NPRP-09-476-1-078.
62 citations
TL;DR: In this paper, the mass and distance measurements of two single-lens events from the 2015 Spitzer microlensing campaign are reported, and it is shown that the lens of OGLE-2015-BLG-1268 is very likely a brown dwarf.
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.
55 citations
TL;DR: The OGLE-2012-BLG-0563Lb microlensing exoplanet was discovered in this paper with the planet-star mass ratio of 1 x 10−3.
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
55 citations
TL;DR: In this article, the authors reported 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).
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.
51 citations
California Institute of Technology1, University of Warsaw2, Ohio State University3, Chungbuk National University4, University of Salerno5, Istituto Nazionale di Fisica Nucleare6, Tel Aviv University7, University of Copenhagen8, Harvard University9, University of Warwick10, University of Canterbury11, Korea Astronomy and Space Science Institute12, Kyung Hee University13, Las Cumbres Observatory Global Telescope Network14, Heidelberg University15, Qatar Foundation16, University of St Andrews17, Open University18, Liverpool John Moores University19, European Southern Observatory20, Institut d'Astrophysique de Paris21, Chinese Academy of Sciences22, University of Manchester23, Tsinghua University24, Peking University25
TL;DR: In this paper, the authors reported 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⊙ (80% probability).
Abstract: We report the detection and mass measurement of a binary lens OGLE-2015-BLG-1285La,b, with the more massive component having M1 > 1.35 M⊙ (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 (NS) or black hole (BH). The system has a projected separation r⊥ = 6.1 ± 0.4 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 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 30 m 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 BHs and NSs 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.
44 citations
University of Warsaw1, Chungbuk National University2, Osaka University3, Tel Aviv University4, Ohio State University5, University of Rijeka6, Las Cumbres Observatory Global Telescope Network7, University of Copenhagen8, University of Notre Dame9, Istituto Nazionale di Fisica Nucleare10, University of Concepción11, University of Cambridge12, Nagoya University13, Massey University14, University of Auckland15, Konan University16, University of British Columbia17, College of Industrial Technology18, Victoria University of Wellington19, Texas A&M University20, Korea Astronomy and Space Science Institute21, Auckland University of Technology22, Harvard University23, University of Canterbury24, University of Toulouse25, Institut d'Astrophysique de Paris26, European Southern Observatory27, University of Tasmania28, University of Vienna29, Space Telescope Science Institute30, NASA Exoplanet Science Institute31, Heidelberg University32, Qatar Foundation33, University of St Andrews34, Max Planck Society35, Liverpool John Moores University36, University of Salerno37, University of Göttingen38, Chinese Academy of Sciences39, University of Manchester40, Aarhus University41, Perimeter Institute for Theoretical Physics42, National Autonomous University of Mexico43, Keele University44, University of Liège45, Ames Research Center46
TL;DR: The OGLE-2011-BLG-0265 microlensing system as discussed by the authors was the first to detect a Jupiter-mass planet orbiting an M-dwarf star.
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. However, the final microlensing solution remains 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-p = 0.9 +/- 0.3 M-J, and the planet is orbiting a star with a mass M = 0.22 +/- 0.06 M-circle dot. The second possible configuration (2 sigma away) consists of a planet with M-p = 0.6 +/- 0.3M(J) and host star with M = 0.14 +/- 0.06M(circle dot). The system is located in the Galactic disk 3-4 kpc toward 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.
38 citations
Institut d'Astrophysique de Paris1, University of Canterbury2, Massey University3, University of Notre Dame4, University of St Andrews5, Peking University6, University of Toulouse7, Ohio State University8, University of Tasmania9, Niels Bohr Institute10, Space Telescope Science Institute11, Osaka University12, Qatar Foundation13, University of Rijeka14, University of Vienna15, Chungbuk National University16, San Francisco State University17, Korea Astronomy and Space Science Institute18, Las Cumbres Observatory Global Telescope Network19, Curtin University20, Nagoya University21, University of Auckland22, Vaughn College of Aeronautics and Technology23, Victoria University, Australia24, University at Albany, SUNY25, Kyoto Sangyo University26
TL;DR: In this paper, C.H., M.D. and M.C. were supported by NPRP grant NPRP-09-476-1-78 from the Qatar National Research Fund (a member of Qatar Foundation).
Abstract: A.C. acknowledges financial support from the Emergence UPMC 2012 grant. Work by C.H. was supported by Creative Research Initiative Program (2009-0081561) of National Research Foundation of Korea. K.H., M.D. and M.H. are supported by NPRP grant NPRP-09-476-1-78 from the Qatar National Research Fund (a member of Qatar Foundation). M.H. acknowledges support from the Villum foundation. S.D. is supported by “the Strategic Priority Research Program- The Emergence of Cosmological Structures” of the Chinese Academy of Sciences (grant No. XDB09000000).
32 citations
Chungbuk National University1, Ohio State University2, University of Warsaw3, University of Cambridge4, Nagoya University5, University of Notre Dame6, Massey University7, University of Auckland8, Osaka University9, Vaughn College of Aeronautics and Technology10, Victoria University of Wellington11, Kyoto Sangyo University12, University of Canterbury13, Institut d'Astrophysique de Paris14, University of St Andrews15, University of Rijeka16, University of Vienna17, University of Toulouse18, University of Tasmania19, University of the Free State20, University of Hawaii21, Niels Bohr Institute22, San Francisco State University23, Space Telescope Science Institute24, Heidelberg University25, Texas A&M University26, Korea Astronomy and Space Science Institute27, Tel Aviv University28, Auckland University of Technology29, Weizmann Institute of Science30, Harvard University31, European Southern Observatory32, University of Hamburg33, Max Planck Society34, Liverpool John Moores University35, Las Cumbres Observatory Global Telescope Network36, Queen Mary University of London37
TL;DR: In this article, the authors reanalyze microlensing events in the published list of anomalous events that were observed from the Optical Gravitational Lensing Experiment (OGLE) lensing survey conducted during the 2004-2008 period.
Abstract: We reanalyze microlensing events in the published list of anomalous events that were observed from the Optical Gravitational Lensing Experiment (OGLE) lensing survey conducted during the 2004–2008 period. In order to check the existence of possible degenerate solutions and extract extra information, we conduct analyses based on combined data from other survey and follow-up observation and consider higher-order effects. Among the analyzed events, we present analyses of eight events for which either new solutions are identified or additional information is obtained. We find that the previous binary-source interpretations of five events are better interpreted by binary-lens models. These events include OGLE-2006-BLG-238, OGLE-2007-BLG-159, OGLE-2007-BLG-491, OGLE-2008-BLG-143, and OGLE-2008-BLG-210. With additional data covering caustic crossings, we detect finite-source effects for six events including OGLE-2006-BLG-215, OGLE-2006-BLG-238, OGLE-2006-BLG-450, OGLE-2008-BLG-143, OGLE-2008-BLG-210, and OGLE-2008-BLG-513. Among them, we are able to measure the Einstein radii of three events for which multi-band data are available. These events are OGLE-2006-BLG-238, OGLE-2008-BLG-210, and OGLE-2008-BLG-513. For OGLE-2008-BLG-143, we detect higher-order effects induced by the changes of the observer's position caused by the orbital motion of the Earth around the Sun. In addition, we present degenerate solutions resulting from the known close/wide or ecliptic degeneracy. Finally, we note that the masses of the binary companions of the lenses of OGLE-2006-BLG-450 and OGLE-2008-BLG-210 are in the brown-dwarf regime.
TL;DR: In this article, the authors reanalyze microlensing events in the published list of anomalous events that were observed from the OGLE lensing survey conducted during 2004-2008 period.
Abstract: We reanalyze microlensing events in the published list of anomalous events that were observed from the OGLE lensing survey conducted during 2004-2008 period. In order to check the existence of possible degenerate solutions and extract extra information, we conduct analyses based on combined data from other survey and follow-up observation and consider higher-order effects. Among the analyzed events, we present analyses of 8 events for which either new solutions are identified or additional information is obtained. We find that the previous binary-source interpretations of 5 events are better interpreted by binary-lens models. These events include OGLE-2006-BLG-238, OGLE-2007-BLG-159, OGLE-2007-BLG-491, OGLE-2008-BLG-143, and OGLE-2008-BLG-210. With additional data covering caustic crossings, we detect finite-source effects for 6 events including OGLE-2006-BLG-215, OGLE-2006-BLG-238, OGLE-2006-BLG-450, OGLE-2008-BLG-143, OGLE-2008-BLG-210, and OGLE-2008-BLG-513. Among them, we are able to measure the Einstein radii of 3 events for which multi-band data are available. These events are OGLE-2006-BLG-238, OGLE-2008-BLG-210, and OGLE-2008-BLG-513. For OGLE-2008-BLG-143, we detect higher-order effect induced by the changes of the observer's position caused by the orbital motion of the Earth around the Sun. In addition, we present degenerate solutions resulting from the known close/wide or ecliptic degeneracy. Finally, we note that the masses of the binary companions of the lenses of OGLE-2006-BLG-450 and OGLE-2008-BLG-210 are in the brown-dwarf regime.
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TL;DR: In this article, the OGLE-2005-BLG-169Lb planetary system was confirmed using the Wide Field Camera 3 (WFC3) observations of the source and lens stars.
Abstract: We present Hubble Space Telescope (HST) Wide Field Camera 3 (WFC3) observations of the source and lens stars for planetary microlensing event OGLE-2005-BLG-169, which confirm the relative proper motion prediction due to the planetary light curve signal observed for this event. This (and the companion Keck result) provide the first confirmation of a planetary microlensing signal, for which the deviation was only 2%. The follow-up observations determine the flux of the planetary host star in multiple passbands and remove light curve model ambiguity caused by sparse sampling of part of the light curve. This leads to a precise determination of the properties of the OGLE-2005-BLG-169Lb planetary system. Combining the constraints from the microlensing light curve with the photometry and astrometry of the HST/WFC3 data, we find star and planet masses of M_* = 0.69+- 0.02 M_solar and m_p = 14.1 +- 0.9 M_earth. The planetary microlens system is located toward the Galactic bulge at a distance of D_L = 4.1 +- 0.4 kpc, and the projected star-planet separation is a_perp = 3.5 +- 0.3 AU, corresponding to a semi-major axis of a = 4.0 (+2.2 -0.6) AU.
Institut d'Astrophysique de Paris1, University of Canterbury2, Massey University3, University of Notre Dame4, University of St Andrews5, Peking University6, University of Toulouse7, Ohio State University8, University of Tasmania9, Niels Bohr Institute10, Space Telescope Science Institute11, Osaka University12, Qatar Foundation13, University of Rijeka14, University of Vienna15, Chungbuk National University16, San Francisco State University17, Korea Astronomy and Space Science Institute18, Las Cumbres Observatory Global Telescope Network19, Curtin University20, Nagoya University21, University of Auckland22, Vaughn College of Aeronautics and Technology23, Victoria University, Australia24, University at Albany, SUNY25
TL;DR: In this paper, the first brown dwarf companion to a Sun-like star detected through gravitational microlensing was detected by a network of telescopes from the PLANET, MOA, and uFUN collaborations and observed at high angular resolution using the NaCo instrument at the VLT.
Abstract: We present the analysis of MOA-2007-BLG-197Lb, the first brown dwarf companion to a Sun-like star detected through gravitational microlensing. The event was alerted and followed-up photometrically by a network of telescopes from the PLANET, MOA, and uFUN collaborations, and observed at high angular resolution using the NaCo instrument at the VLT. From the modelling of the microlensing light curve, we derived the binary lens separation in Einstein radius units (s~1.13) and a mass ratio of (4.732+/-0.020)x10^{-2}. Annual parallax, lens orbital motion and finite source effects were included in the models. To recover the lens system's physical parameters, we combined the resulting light curve best-fit parameters with (J,H,Ks) magnitudes obtained with VLT NaCo and calibrated using IRSF and 2MASS data. We derived a lens total mass of 0.86+/-0.04 Msun and a lens distance of 4.2+/-0.3 kpc. We find that the companion of MOA-2007-BLG-197L is a brown dwarf of 41+/-2 Mjup observed at a projected separation of 4.3+/-0.1 AU, and orbits a 0.82+/-0.04 Msun G-K dwarf star. We study the statistical properties of this population of brown dwarfs detected by microlensing, transit, radial velocity, and direct imaging (most of these objects orbit solar-type stars), and we performed a two-dimensional, non-parametric probability density distribution fit to the data, which draws a structured brown dwarf landscape. We confirm the existence of a region that is strongly depleted in objects at short periods and intermediate masses (P 500 d) and high masses (M>50 Mjup). While these data provide important clues on mechanisms of brown dwarfs formation, more data are needed to establish their relative importance, in particular as a function of host star mass.