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TRIPLE MICROLENS OGLE-2008-BLG-092L: BINARY STELLAR SYSTEM WITH A CIRCUMPRIMARY URANUS-TYPE PLANET
Poleski, Radosław,Skowron, Jan,Udalski, Andrzej,Han, Cheongho,Kozłowski, Szymon,Wyrzykowski, Łukasz,Dong, Subo,Szymań,ski, Michał K.,Kubiak, Marcin,Pietrzyń,ski, Grzegorz,Soszyń,ski, Ig IOP Publishing 2014 The Astrophysical journal Vol.795 No.1
<P>We present the gravitational microlensing discovery of a 4 M-Uranus planet that orbits a 0.7 M circle dot star at approximate to 18 AU. This is the first known analog of Uranus. Similar planets, i.e., cold ice giants, are inaccessible to either radial velocity or transit methods because of the long orbital periods, while low reflected light prevents direct imaging. We discuss how similar planets may contaminate the sample of the very short microlensing events that are interpreted as free-floating planets with an estimated rate of 1.8 per main-sequence star. Moreover, the host star has a nearby stellar (or brown dwarf) companion. The projected separation of the planet is only about three times smaller than that of the companion star, suggesting significant dynamical interactions.</P>
Poleski, Radosław,Zhu, Wei,Christie, Grant W.,Udalski, Andrzej,Gould, Andrew,Bachelet, Etienne,Skottfelt, Jesper,Novati, Sebastiano Calchi,Szymań,ski, M. K.,Soszyń,ski, I.,Pietrzyń,ski, American Astronomical Society 2016 The Astrophysical journal Vol.823 No.1
<P>The microlensing event OGLE-2015-BLG-0448 was observed by Spitzer and lay within the tidal radius of the globular cluster NGC 6558. The event had moderate magnification and was intensively observed, hence it had the potential to probe the distribution of planets in globular clusters. We measure the proper motion of NGC 6558 (mu(cl) (N, E) = (+0.36 +/- 0.10, +1.42 +/- 0.10) mas yr(-1)) as well as the source and show that the lens is not a cluster member. Even though this particular event does not probe the distribution of planets in globular clusters, other potential cluster lens events can be verified using our methodology. Additionally, we find that microlens parallax measured using Optical Gravitational Lens Experiment (OGLE) photometry is consistent with the value found based on the light curve displacement between the Earth and Spitzer.</P>
Henderson, Calen B.,Poleski, Radosław,Penny, Matthew,Street, Rachel A.,Bennett, David P.,Hogg, David W.,Gaudi, B. Scott,Zhu, W.,Barclay, T.,Barentsen, G.,Howell, S. B.,Mullally, F.,Udalski, A.,Szyma Astronomical Society of the Pacific 2016 Publications of the Astronomical Society of the Pa Vol.128 No.970
<P>K2's Campaign 9 (K2C9) will conduct a similar to 3.7 deg(2) survey toward the Galactic bulge from 2016 April 22 through July 2 that will leverage the spatial separation between K2 and the Earth to facilitate measurement of the microlens parallax pi(E) for greater than or similar to 170 microlensing events. These will include several that are planetary in nature as well as many short-timescale microlensing events, which are potentially indicative of free-floating planets (FFPs). These satellite parallax measurements will in turn allow for the direct measurement of the masses of and distances to the lensing systems. In this article we provide an overview of the K2C9 space-and ground-based microlensing survey. Specifically, we detail the demographic questions that can be addressed by this program, including the frequency of FFPs and the Galactic distribution of exoplanets, the observational parameters of K2C9, and the array of resources dedicated to concurrent observations. Finally, we outline the avenues through which the larger community can become involved, and generally encourage participation in K2C9, which constitutes an important pathfinding mission and community exercise in anticipation of WFIRST.</P>
OGLE-2013-BLG-0578 L: A MICROLENSING BINARY COMPOSED OF A BROWN DWARF AND AN M DWARF
Park, H.,Udalski, A.,Han, C.,Poleski, R.,Skowron, J.,Kozłowski, S.,Wyrzykowski, Ł.,Szymań,ski, M. K.,Pietrukowicz, P.,Pietrzyń,ski, G.,Soszyń,ski, I.,Ulaczyk, K. IOP Publishing 2015 The Astrophysical journal Vol.805 No.2
<P>Determining the physical parameters of binary microlenses is hampered by the lack of information about the angular Einstein radius due to the difficulty involved in resolving caustic crossings. In this paper, we present an analysis of the binary microlensing event OGLE-2013-BLG-0578, for which the caustic exit was precisely predicted in advance from real-time analysis, enabling us to densely resolve the caustic crossing and to measure the Einstein radius. From the mass measurement of the lens system based on the Einstein radius, combined with additional information about the lens parallax, we determine that the lens is a binary composed of a late-type M dwarf primary and a substellar brown dwarf companion. This event demonstrates the capability of current real-time microlensing modeling and the usefulness of microlensing for detecting and characterizing faint or dark objects in the Galaxy.</P>
THE FIRST NEPTUNE ANALOG OR SUPER-EARTH WITH A NEPTUNE-LIKE ORBIT: MOA-2013-BLG-605LB
Sumi, T.,Udalski, A.,Bennett, D. P.,Gould, A.,Poleski, R.,Bond, I. A.,Skowron, J.,Rattenbury, N.,Pogge, R. W.,Bensby, T.,Beaulieu, J. P.,Marquette, J. B.,Batista, V.,Brillant, S.,Abe, F.,Asakura, Y.,B American Astronomical Society 2016 The Astrophysical journal Vol.825 No.2
<P>We present the discovery of the first Neptune analog exoplanet or super-Earth with a Neptune-like orbit, MOA-2013-BLG-605Lb. This planet has a mass similar to that of Neptune or a super-Earth and it orbits at 9 similar to 14 times the expected position of the snow line, a(snow), which is similar to Neptune's separation of 11 a(snow) from the Sun. The planet/host-star mass ratio is q = (3.6 +/- 0.7) x 10(-4) and the projected separation normalized by the Einstein radius is s = 2.39 +/- 0.05. There are three degenerate physical solutions and two of these are due to a new type of degeneracy in the microlensing parallax parameters, which we designate 'the wide degeneracy.' The three models have (i) a Neptune-mass planet with a mass of M-p = 21(-7)(+6)M(circle plus) orbiting a low-mass M-dwarf with a mass of M-h = 0.19(-0.06)(+0.05)M(circle dot), (ii) a mini-Neptune with M-p = 7.9(-1.2)(+1.8)M(circle plus) orbiting a brown dwarf host with M-h = 0.068(-0.011)(+0.019)M(circle dot), and (iii) a super-Earth with M-p = 3.2(-0.3)(+0.5)M(circle plus) orbiting a low-mass brown dwarf host with M-h = 0.025(-0.004)(+0.005)M(circle dot), which is slightly favored. The 3D planet-host separations are 4.6(-1.2)(+4.7) au, 2.1(-0.2) (+1.0) au, and 0.94(-0.02)(+0.67) au, which are 8.9(-1.4)(+10.5), 12(-1)(+7), or 14(-1)(+11) times larger than a(snow) for these models, respectively. Keck adaptive optics observations confirm that the lens is faint. This discovery suggests that low-mass planets with Neptune-like orbits are common. Therefore processes similar to the one that formed Neptune in our own solar system or cold super-Earths may be common in other solar systems.</P>
OGLE-2016-BLG-0596Lb: A High-mass Planet from a High-magnification Pure-survey Microlensing Event
Mró,z, P.,Han, C.,Udalski, A.,Poleski, R.,Skowron, J.,Szymań,ski, M. K.,Soszyń,ski, I.,Pietrukowicz, P.,Kozłowski, S.,Ulaczyk, K.,Wyrzykowski, Ł.,Pawlak, M.,Albrow, M. D.,Cha, S.-M.,Ch American Institute of Physics 2017 The Astronomical journal Vol.153 No.4
<P>We report the discovery of a high mass ratio planet, q = 0.012, i.e., 13 times higher than the Jupiter/Sun ratio. The host mass has not yet been measured but can be determined or strongly constrained from adaptive optics imaging. The planet was discovered in a small archival study of high-magnification events in pure-survey microlensing data, which was unbiased by the presence of anomalies. The fact that it was previously unnoticed may indicate that more such planets lie in archival data and could be discovered by a similar systematic study. In order to understand the transition from predominantly survey+followup to predominately survey-only planet detections, we conduct the first analysis of these detections in the observational (s, q) plane. Here s is the projected separation in units of the Einstein radius. We find some evidence that survey+followup is relatively more sensitive to planets near the Einstein ring, but that there is no statistical difference in sensitivity by mass ratio.</P>
An Isolated Microlens Observed from <i>K2</i> , <i>Spitzer</i> , and Earth
Zhu, Wei,Udalski, A.,Huang, C. X.,Novati, S. Calchi,Sumi, T.,Poleski, R.,Skowron, J.,Mró,z, P.,Szymań,ski, M. K.,Soszyń,ski, I.,Pietrukowicz, P.,Kozłowski, S.,Ulaczyk, K.,Pawlak, M.,Be American Astronomical Society 2017 ASTROPHYSICAL JOURNAL LETTERS - Vol.849 No.2
Jung, Y. K.,Udalski, A.,Sumi, T.,Han, C.,Gould, A.,Skowron, J.,Kozłowski, S.,Poleski, R.,Wyrzykowski, Ł.,Szymań,ski, M. K.,Pietrzyń,ski, G.,Soszyń,ski, I.,Ulaczyk, K.,Pietrukowicz, P.,M IOP Publishing 2015 The Astrophysical journal Vol.798 No.2
<P>We present an analysis of the gravitational microlensing event OGLE-2013-BLG-0102. The light curve of the event is characterized by a strong short-term anomaly superposed on a smoothly varying lensing curve with a moderate magnification A(max) similar to 1.5. It is found that the event was produced by a binary lens with a mass ratio between the components of q = 0.13 and the anomaly was caused by the passage of the source trajectory over a caustic located away from the barycenter of the binary. Based on the analysis of the effects on the light curve due to the finite size of the source and the parallactic motion of the Earth, we determine the physical parameters of the lens system. The measured masses of the lens components are M-1 = 0.096 +/- 0.013 M-circle dot and M-2 = 0.012 +/- 0.002 M-circle dot, which correspond to near the hydrogen-burning and deuterium-burning mass limits, respectively. The distance to the lens is 3.04 +/- 0.31 kpc and the projected separation between the lens components is 0.80 +/- 0.08 AU.</P>
A VENUS-MASS PLANET ORBITING A BROWN DWARF: A MISSING LINK BETWEEN PLANETS AND MOONS
Udalski, A.,Jung, Y. K.,Han, C.,Gould, A.,Kozłowski, S.,Skowron, J.,Poleski, R.,Soszyń,ski, I.,Pietrukowicz, P.,Mró,z, P.,Szymań,ski, M. K.,Wyrzykowski, Ł.,Ulaczyk, K.,Pietrzyń,sk IOP Publishing 2015 The Astrophysical journal Vol.812 No.1
<P>The co-planarity of solar system planets led Kant to suggest that they formed from an accretion disk, and the discovery of hundreds of such disks around young stars as well as hundreds of co-planar planetary systems by the Kepler satellite demonstrate that this formation mechanism is extremely widespread. Many moons in the solar system, such as the Galilean moons of Jupiter, also formed out of the accretion disks that coalesced into the giant planets. Here we report the discovery of an intermediate system, OGLE-2013-BLG-0723LB/Bb, composed of a Venus-mass planet orbiting a brown dwarf, which may be viewed either as a scaled-down version of a planet plus a star or as a scaled-up version of a moon plus a planet orbiting a star. The latter analogy can be further extended since they orbit in the potential of a larger, stellar body. For ice-rock companions formed in the outer parts of accretion disks, like Uranus and Callisto, the scaled masses and separations of the three types of systems are similar, leading us to suggest that the formation processes of companions within accretion disks around stars, brown dwarfs, and planets are similar.</P>
OGLE-2016-BLG-1045: A Test of Cheap Space-based Microlens Parallaxes
Shin, I.-G.,Udalski, A.,Yee, J. C.,Novati, S. Calchi,Christie, G.,Poleski, R.,Mró,z, P.,Skowron, J.,Szymań,ski, M. K.,Soszyń,ski, I.,Pietrukowicz, P.,Kozłowski, S.,Ulaczyk, K.,Pawlak, American Astronomical Society 2018 The Astrophysical journal Vol.863 No.1