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Microstructure, Texture and Mechanical Properties of Titanium Grade 2 Processed by ECAP (Route C)
M. Wroński,K. Wierzbanowski,D. Wojtas,E. Szyfner,R. Z. Valiev,J. Kawałko,K. Berent,K. Sztwiertnia 대한금속·재료학회 2018 METALS AND MATERIALS International Vol.24 No.4
In the present work the properties of titanium grade 2 after ECAP processing with original route and regimes (route C, channelangle = 120°, deformation temperature 300 °C, number of passes up to 8) were examined. Texture development andmicrostructure parameters after ECAP processing and after recrystallization were determined using electron back scatterdiff raction and analysed. A signifi cant increase of the mechanical strength accompanied by some increase of ductility wasobserved in the deformed samples. The kernel average misorientation and average grain orientation spread were stronglyincreased after deformation, which confi rms the material refi nement and fragmentation. The proportion of low angle boundariesincreased after four ECAP passes, but after four consecutive passes high angle grain boundaries became predominant. Nodeformation twins were observed after four and eight ECAP passes. The material recrystallized after deformation retaineda fi ne grain microstructure. The textures of deformed and recrystallized samples were determined. It was found that textureafter 8 passes is more homogeneous that that after 4 passes, which partly explains higher ductility of this fi rst sample.
A Neptune-mass Free-floating Planet Candidate Discovered by Microlensing Surveys
Mró,z, Przemek,Ryu, Y.-H.,Skowron, J.,Udalski, A.,Gould, A.,Szymań,ski, M. K.,Soszyń,ski, I.,Poleski, R.,Pietrukowicz, P.,Kozłowski, S.,Pawlak, M.,Ulaczyk, K.,Albrow, M. D.,Chung, S.-J American Astronomical Society 2018 The Astronomical journal Vol.155 No.3
OGLE-2013-BLG-0132Lb and OGLE-2013-BLG-1721Lb: Two Saturn-mass Planets Discovered around M-dwarfs
Mró,z, Przemek,Udalski, A.,Bond, I. A.,Skowron, J.,Sumi, T.,Han, C.,Szymań,ski, M. K.,Soszyń,ski, I.,Poleski, R.,Pietrukowicz, P.,Kozłowski, S.,Wyrzykowski, Ł.,Ulaczyk, K.,Abe, F.,Asak American Astronomical Society 2017 The Astronomical journal Vol.154 No.5
<P>We present the discovery of two planetary systems consisting of a Saturn-mass planet orbiting an M-dwarf, which were detected in faint microlensing events OGLE-2013-BLG-0132 and OGLE-2013-BLG-1721. The planetary anomalies were covered with high cadence by Optical Gravitational Lensing Experiment (OGLE) and Microlensing Observations in Astrophysics (MOA) photometric surveys. The light curve modeling indicates that the planet-to-host mass ratios are (5.15 +/- 0.28) x 10(-4) and (13.18 +/- 0.72) x 10(-4), respectively. Both events were too short and too faint to measure a reliable parallax signal and hence the lens mass. We therefore used a Bayesian analysis to estimate the masses of both planets: 0.29(-0.13) (+0.16) M-Jup (OGLE-2013-BLG-0132Lb) and 0.64(-0.31)(+0.35) M-Jup (OGLE-2013-BLG-1721Lb). Thanks to a high relative proper motion, OGLE-2013-BLG-0132 is a promising candidate for the high-resolution imaging follow-up. Both planets belong to an increasing sample of sub-Jupiter-mass planets orbiting M-dwarfs beyond the snow line.</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>
Centrality dependence of subthresholdϕmeson production in Ni + Ni collisions at1.9AGeV
Piasecki, K.,Tymiń,ski, Z.,Herrmann, N.,Averbeck, R.,Andronic, A.,Barret, V.,Basrak, Z.,Bastid, N.,Benabderrahmane, M. L.,Berger, M.,Buehler, P.,Cargnelli, M.,Č,aplar, R.,Cordier, E.,Crochet American Physical Society 2016 Physical Review C Vol.94 No.1
<P>We analyzed the phi meson production in central Ni + Ni collisions at a beam kinetic energy of 1.93A GeV with the FOPI spectrometer and found a production probability per event of [8.6 +/- 1.6(stat) +/- 1.5(syst)] x 10(-4). This new data point allows us for the first time to inspect the centrality dependence of subthreshold phi meson production in heavy-ion collisions. The rise of phi meson multiplicity per event with mean number of participants can be parametrized by a power function with exponent alpha = 1.8 +/- 0.6. The ratio of phi to K- production yields seems not to depend, within the experimental uncertainties, on the collision centrality, and the average of measured values was found to be 0.36 +/- 0.05.</P>
Han, C.,Udalski, A.,Bozza, V.,Szymań,ski, M. K.,Soszyń,ski, I.,Skowron, J.,Mró,z, P.,Poleski, R.,Pietrukowicz, P.,Kozłowski, S.,Ulaczyk, K.,Wyrzykowski, Ł.,Novati, S. Calchi,D’Ago, G. American Astronomical Society 2017 The Astrophysical journal Vol.843 No.2
<P>Due to the nature of the gravitational field, microlensing, in principle, provides an important tool for detecting faint and even dark brown dwarfs. However, the number of identified brown dwarfs is limited due to the difficulty of the lens mass measurement that is needed to check the substellar nature of the lensing object. In this work, we report a microlensing brown dwarf discovered from an analysis of the gravitational binary-lens event OGLE-2014-BLG1112. We identify the brown dwarf nature of the lens companion by measuring the lens mass from the detections of both microlens-parallax and finite-source effects. We find that the companion has a mass of. ' ( 3.03 +/- 0.78) 10(-2) M-circle dot and it is orbiting a solar-type primary star with a mass of 1.07 +/- 0.28 M-circle dot. The estimated projected separation between the lens components is 9.63 +/- 1.33 au and the distance to the lens is 4.84 +/- 0.67 kpc. We discuss the usefulness of space-based microlensing observations for detecting brown dwarfs through the channel of binary-lens events.</P>
OGLE-2017-BLG-0373Lb: A Jovian Mass-Ratio Planet Exposes A New Accidental Microlensing Degeneracy
Skowron, J.,Ryu, Y.-H.,Hwang, K.-H.,Udalski, A.,Mró,z, P.,Kozłowski, S.,Soszyń,ski, I.,Pietrukowicz, P.,Szymań,ski, M. K.,Poleski, R. COPERNICUS FOUNDATION FOR POLISH ASTRONOMY 2018 Acta astronomica Vol.68 No.1
Han, C.,Udalski, A.,Gould, A.,Zhu, Wei,Szymań,ski, M. K.,Soszyń,ski, I.,Skowron, J.,Mró,z, P.,Poleski, R.,Pietrukowicz, P.,Kozłowski, S.,Ulaczyk, K.,Pawlak, M.,Yee, J. C.,Beichman, C. American Astronomical Society 2017 The Astrophysical journal Vol.834 No.1
<P>In this paper, we present an analysis of the binary gravitational microlensing event OGLE-2015-BLG-0196. The event lasted for almost a year, and the light curve exhibited significant deviations from the lensing model based on the rectilinear lens-source relative motion, enabling us to measure the microlens parallax. The ground-based microlens parallax is confirmed by the data obtained from space-based microlens observations using the Spitzer telescope. By additionally measuring the angular Einstein radius from the analysis of the resolved caustic crossing, the physical parameters of the lens are determined up to the twofold degeneracy, u(0) < 0 and u(0) > 0, solutions caused by the well-known 'ecliptic' degeneracy. It is found that the binary lens is composed of two M dwarf stars with similar masses, M-1 = 0.38 +/- 0.04M(circle plus) (0.50 +/- 0.05M(circle plus)) and M-2 = 0.38 +/- 0.04M(circle plus) (0.55 +/- 0.06M(circle plus)), and the distance to the lens is D-L = 2.77. +/- 0.23 kpc (3.30 +/- 0.29 kpc). Here the physical parameters outside and inside the parentheses are for the u(0) < 0 and u(0) > 0 solutions, respectively.</P>
OGLE-2014-BLG-0289: Precise Characterization of a Quintuple-peak Gravitational Microlensing Event
Udalski, A.,Han, C.,Bozza, V.,Gould, A.,Bond, I. A.,Mró,z, P.,Skowron, J.,Wyrzykowski, Ł.,Szymań,ski, M. K.,Soszyń,ski, I.,Ulaczyk, K.,Poleski, R.,Pietrukowicz, P.,Kozłowski, S.,Abe, F American Astronomical Society 2018 The Astrophysical journal Vol.853 No.1
<P>We present the analysis of the binary-microlensing event OGLE-2014-BLG-0289. The event light curve exhibits five very unusual peaks, four of which were produced by caustic crossings and the other by a cusp approach. It is found that the quintuple-peak features of the light curve provide tight constraints on the source trajectory, enabling us to precisely and accurately measure the microlensing parallax pi(E). Furthermore, the three resolved caustics allow us to measure the angular Einstein radius theta(E). From the combination of pE and qE, the physical lens parameters are uniquely determined. It is found that the lens is a binary composed of two M dwarfs with masses M-1 = 0.52 +/- 0.04 M-circle dot and M-2 = 0.42 +/- 0.03 M-circle dot separated in projection by a(perpendicular to) = 6.4 +/- 0.5 au. The lens is located in the disk with a distance of D-L = 3.3 +/- 0.3 kpc. The reason for the absence of a lensing signal in the Spitzer data is that the time of observation corresponds to the flat region of the light curve.</P>
Han, C.,Udalski, A.,Lee, C.-U.,Gould, A.,Bozza, V.,Szymań,ski, M. K.,Soszyń,ski, I.,Skowron, J.,Mró,z, P.,Poleski, R.,Pietrukowicz, P.,Kozłowski, S.,Ulaczyk, K.,Wyrzykowski, Ł.,Pawlak, American Astronomical Society 2016 The Astrophysical journal Vol.827 No.1
<P>In this paper, we demonstrate the severity of the degeneracy between the microlens-parallax and lens-orbital effects by presenting the analysis of the gravitational binary-lens event OGLE-2015-BLG-0768. Despite the obvious deviation from the model based on the linear observer motion and the static binary, it is found that the residual can be almost equally well explained by either the parallactic motion of the Earth or the rotation of the binary-lens axis, resulting in the severe degeneracy between the two effects. We show that the degeneracy can be readily resolved with the additional data provided by space-based microlens parallax observations. By enabling us. to distinguish between the two higher-order effects, space-based microlens parallax observations will not only. make it possible to. accurately determine the physical lens parameters but also to further constrain the orbital parameters of binary lenses.</P>