A5059525093- Rare-earth and actinide compounds
- Iron-based superconductors research
- Magnetic and transport properties of perovskites and related materials
- Advanced Condensed Matter Physics
- Magnetic Properties of Alloys
- Stellar, planetary, and galactic studies
- Thermodynamic and Structural Properties of Metals and Alloys
- Inorganic Chemistry and Materials
- Physics of Superconductivity and Magnetism
- Astronomy and Astrophysical Research
- High-pressure geophysics and materials
- Astrophysics and Star Formation Studies
- Solid-state spectroscopy and crystallography
- Astronomical Observations and Instrumentation
- Boron and Carbon Nanomaterials Research
- Crystal Structures and Properties
- Chemical Thermodynamics and Molecular Structure
- X-ray Diffraction in Crystallography
- Nuclear Materials and Properties
- Adaptive optics and wavefront sensing
- Gamma-ray bursts and supernovae
- Astro and Planetary Science
- Nuclear physics research studies
- Crystallization and Solubility Studies
- History and Developments in Astronomy
Hokkaido University
2016-2025
Shinshu University
2024
High Energy Accelerator Research Organization
2018
Institute for Condensed Matter Physics of the National Academy of Sciences of Ukraine
2018
The University of Tokyo
2005-2016
University of California, San Diego
2005-2014
Niigata University
2002-2009
Japan Aerospace Exploration Agency
2005-2009
Applied Physical Sciences (United States)
2005-2008
Nagoya University
1997-2005
We describe observations carried out by the MOA group of Galactic Bulge during 2000 that were designed to detect efficiently gravitational microlensing faint stars in which magnification is high and/or short duration. These events are particularly useful for studies extra-solar planets and stars. Approximately 17 degrees square monitored at a sampling rate up 6 times per night. The images analysed real-time using difference imaging technique. Twenty candidates detected, 8 alerted community...
We present observations of the unusual microlensing event OGLE 2003-BLG-235/MOA 2003-BLG-53. In this event, a short-duration (~7 days) low-amplitude deviation in light curve due to single-lens profile was observed both MOA (Microlensing Observations Astrophysics) and (Optical Gravitational Lensing Experiment) survey observations. find that features can only be reproduced using binary model with an extreme (planetary) mass ratio 0.0039 for lensing system. If lens system comprises...
We combine all available information to constrain the nature of OGLE-2005-BLG-071Lb, second planet discovered by microlensing and first in a high-magnification event. These include photometric astrometric measurements from Hubble Space Telescope, as well constraints higher order effects extracted ground-based light curve, such microlens parallax, planetary orbital motion finite-source effects. Our primary analysis leads conclusion that host Jovian OGLE-2005-BLG-071Lb is an M dwarf foreground...
The elastic properties of a filled skutterudite ${\mathrm{PrOs}}_{4}{\mathrm{Sb}}_{12}$ with heavy fermion superconductivity at ${T}_{\mathrm{C}}=1.85\mathrm{K}$ have been investigated. softening ${(C}_{11}\ensuremath{-}{C}_{12})/2$ and ${C}_{44}$ lowering temperature down to ${T}_{\mathrm{C}}$ indicates that the quadrupolar fluctuation due CEF state plays role for Cooper paring in superconducting phase ${\mathrm{PrOs}}_{4}{\mathrm{Sb}}_{12}.$ A Debye-type dispersion constants around 30 K...
We analyze the data of gravitational microlensing survey carried out by Microlensing Observations in Astrophysics (MOA) group during 2000 toward Galactic bulge (GB). Our observations are designed to detect efficient high-magnification events with faint source stars and short-timescale events, increasing sampling rate up ~6 times per night using Difference Image Analysis (DIA). 28 candidates 12 GB fields corresponding 16 deg2. use Monte Carlo simulations estimate our event detection...
We present analysis of MACHO Alert 95-30, a dramatic gravitational microlensing event toward the Galactic bulge whose peak magnification departs significantly from standard point-source model. 95-30 was observed in real time by Global Microlensing Network (GMAN), which obtained densely sampled photometric and spectroscopic data throughout event. interpret light-curve "fine structure" as indicating transit lens across extended face source star. This signifies resolution star several...
Magnetization measurements under direct electric currents were performed for toroidal magnetic ordered state of UNi$_4$B to test a recent theoretical prediction current-induced magnetization in metallic system lacking local inversion symmetry.We found that each the parallel [$2\bar{1}\bar{1}0$] and [$0001$] hexagonal 4-index notation induces uniform direction [$01\bar{1}0$].The observed behavior induced is essentially consistent with prediction; however it also shows an inconsistency...
We present observations of microlensing event MACHO-98-BLG-35 which reached a peak magnification factor almost 80. These by the Microlensing Planet Search (MPS) and MOA Collaborations place strong constraints on possible planetary system lens star show intriguing evidence for low mass planet with fraction $4\times 10^{-5} \leq ε\leq 2\times 10^{-4}$. A giant $ε= 10^{-3}$ is excluded from 95% region between 0.4 2.5 $R_E$ star, where Einstein ring radius lens. This exclusion more extensive...
Physical properties of DyB 4 have been studied by magnetization, specific heat, and ultrasonic measurements. The magnetic entropy change in intermediate phase II indicate that the degeneracy internal degrees freedom is not fully lifted spite formation order. attenuation huge softening C 44 suggest existence electric-quadrupolar (orbital) fluctuations f -electrons. These unusual originate from a geometrical quadrupolar frustration.
Lattice effects in a cerium based clathrate compound ${\mathrm{Ce}}_{3}{\mathrm{Pd}}_{20}{\mathrm{Ge}}_{6}$ with cubic ${\mathrm{Cr}}_{23}{\mathrm{C}}_{6}$-type structure have been investigated by ultrasonic and thermal expansion measurements. Elastic softenings of ${(C}_{11}\ensuremath{-}{C}_{12})/2$ ${C}_{44}$ proportional to the reciprocal temperature $1/T$ above ${T}_{\mathrm{Q}1}=1.25$ K are well described terms quadrupole susceptibility for ground state ${\ensuremath{\Gamma}}_{8}$...
A search for extrasolar planets was carried out in three gravitational microlensing events of high magnification, MACHO 98–BLG–35, 99–LMC–2 and OGLE 00–BUL–12. Photometry derived from observational images by the MOA groups using an image subtraction technique. For additional photometry MPS PLANET included. Planetary modelling a supercluster computing environment. The estimated probability explaining data on 98–BLG–35 without planet is <1 per cent. best planetary model has mass...
Observations of the gravitational microlensing event MOA 2003-BLG-32/OGLE 2003-BLG-219 are presented, for which peak magnification was over 500, highest yet reported. Continuous observations around enabled a sensitive search planets orbiting lens star. No were detected. Planets 1.3 times heavier than Earth excluded from more 50% projected annular region approximately 2.3 to 3.6 astronomical units surrounding star, Uranus-mass 0.9 8.7 units, and Saturn 0.2 60 units. These largest regions...
Gravitational microlensing events of high magnification have been shown to be promising targets for detecting extrasolar planets. However, only a few found using conventional survey techniques. Here we demonstrate that high-magnification can readily in surveys strategy combines high-frequency sampling target fields with on-line difference imaging analysis. We present 10 peak magnifications greater than 40 were detected real-time towards the Galactic bulge during 2001 by Microlensing...
We present tunneling and rattling motions of an off-center guest atom in a cage referring to clathrate crystal ${\mathrm{La}}_{3}{\mathrm{Pd}}_{20}{\mathrm{Ge}}_{6}$. The elastic constant ${C}_{44}$ ${\mathrm{La}}_{3}{\mathrm{Pd}}_{20}{\mathrm{Ge}}_{6}$ shows Debye-type dispersion around $20\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ obeying relaxation time $\ensuremath{\tau}={\ensuremath{\tau}}_{0}\phantom{\rule{0.2em}{0ex}}\mathrm{exp}(E∕{k}_{\mathrm{B}}T)$ with attempt...
In order to elucidate the variety of correlated electron phenomena found in filled skutterudite compounds, experiments were performed on single crystals ternary Ce- and Pr-based arsenides LnT 4 As 12 (Ln = Ce, Pr; T Fe, Ru, Os) pseudoternary antimonides Pr(Os 1- x Ru ) Sb Pr Nd Os . For example, intermediate valence compound CeRu exhibits non-Fermi liquid characteristics, while compounds PrT display ferromagnetic (18 K) for BCS superconductivity (2.4 unknown (2.3 antiferromagnetic (2.2 Os....
Low-temperature elastic properties of the clathrate compound Ce 3 Pd 20 Si 6 were investigated using ultrasonic measurements. Pronounced softening constants ( C 11 - 12 )/2 and 44 with decreasing temperature indicates a precursor electric quadrupole ordering due to Γ 8 quartet ground sate an orbital degeneracy for 8c site ion. A minimum at T =170 mK transition from paramagnetic phase I ordered III. Applied magnetic fields induce antiferro-quadrupole (AFQ) II highly anisotropic character...
We analyze the Galactic bulge microlensing event MOA 2003-BLG-37. Although Einstein timescale is relatively short, tE = 43 days, light curve displays deviations consistent with parallax effects due to Earth's accelerated motion. show that χ2 surface has four distinct local minima are induced by "jerk-parallax" degeneracy, pairs of solutions having projected radii E 1.76 and 1.28 AU, respectively. This second displaying such a degeneracy first toward bulge. For both events, jerk-parallax...
We report a measurement of limb darkening solar-like star in the very high magnification microlensing event MOA 2002-BLG-33. A 15 hour deviation from light curve profile expected for single lens was monitored intensively V and I passbands by five telescopes spanning globe. Our modelling showed to be close binary system whose centre-of-mass passed almost directly front source star. The identified as an F8-G2 main sequence turn-off measured stellar profiles agree with current atmosphere theory...
We have studied a puzzling phase below 17.5 K of URu2Si2 by means resonant X-ray scattering (RXS) near the U MIV absorption edge (E ~ 3.73 keV), using high-quality single-crystalline sample with low residual stress. reconfirm that commensurate (003) superlattice reflection comes purely from antiferromegnetic dipolar order ordering wave vector QAF = (1, 0, 0). No other traces significant RXS been detected in major region (h0l) plane, indicating absence quadrupolar within searched Q range...
We have performed ultrasonic measurements on single-crystalline URu2Si2 with pulsed magnetic fields, in order to check for possible lattice instabilities due the hybridized state and hidden-order of this compound. The elastic constant (C11-C12)/2, which is associated a response {\Gamma}3-type symmetry-breaking (orthorhombic) strain field, shows three-step increase at H > 35 T || c low temperatures, where successive meta-magnetic transitions are observed magnetization. discovered new fact...
Acoustic signatures of the single-site quadrupolar Kondo effect in Y$_{0.966}$Pr$_{0.034}$Ir$_2$Zn$_{20}$ are presented. The elastic constant ($C_{11}-C_{12}$)/2, corresponding to $\Gamma_3$(E)-symmetry electric-quadrupolar response, reveals a logarithmic temperature dependence susceptibility low-magnetic-field region below $\sim$0.3 K. Furthermore, Curie-type divergence down $\sim$1 K indicates that Pr ions this diluted system have non-Kramers ground-state doublet. These observations...