Yuzuru Yoshii

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We report a measurement of the Rossiter–McLaughlin effect in the transiting extrasolar planetary system TrES-1, via simultaneous spectroscopic and photometric observations with the Subaru and MAGNUM telescopes. By modeling the radial velocity anomaly that was observed during a transit, we determine the sky-projected angle between the stellar spin axis and(More)
The chemically most primitive stars provide constraints on the nature of the first stellar objects that formed in the Universe; elements other than hydrogen, helium and traces of lithium present within these objects were generated by nucleosynthesis in the very first stars. The relative abundances of elements in the surviving primitive stars reflect the(More)
We present photometry of HD 189733 during eight transits of its close-in giant planet, and out-of-transit photometry spanning 2 yr. Using the transit photometry, we determine the stellar and planetary radii and the photometric ephemeris. Outside of transits, there are quasi-periodic flux variations with a 13.4 day period that we attribute to stellar(More)
The spectrum of the supernova relic neutrino background (SRN) from collapse-driven supernovae ever occurred in the universe is calculated by using a realistic, time-dependent supernova rate derived from a standard model of galaxy evolution based on the population synthesis method. The SRN spectrum we show here is the most realistic at present, because the(More)
We simulate the dynamical and chemical evolution of a dwarf galaxy embedded in a dark matter halo, using a three-dimensional N -body/SPH simulation code combined with stellar population synthesis. The initial condition is adopted in accord with a 1010M⊙ virialized sphere in a 1σ CDM perturbation which contains 10% baryonic mass. A supersonic spherical(More)
We have developed a simulation code with the techniques which enhance both spatial and time resolution of the PM method for which the spatial resolution is restricted by the spacing of structured mesh. The adaptive mesh refinement (AMR) technique subdivides the cells which satisfy the refinement criterion recursively. The hierarchical meshes are maintained(More)
Deep optical and near-infrared galaxy counts are utilized to estimate the extragalactic background light (EBL) coming from normal galactic light in the universe. Although the slope of number-magnitude relation of the faintest counts is flat enough for the count integration to converge, considerable fraction of EBL from galaxies could still have been missed(More)
We present a deepK -band (2.12μm) imaging of 1 × 1 Subaru Super Deep Field (SSDF) taken with the Subaru adaptive optics (AO) system. Total integration time of 26.8 hours results in the limiting magnitude of K ′ ∼ 24.7 (5σ, 0. 2 aperture) for point sources and K ′ ∼ 23.5 (5σ, 0. 6 aperture) for galaxies, which is the deepest limit ever achieved in the K ′(More)
The kinematics of 122 red giants and 124 RR Lyrae variables in the solar neighborhood is studied using accurate measurements of their proper motions by the Hipparcos astrometry satellite, combined with the published photometric distances, metal abundances and radial velocities. A majority of these sample stars have metal abundances with [Fe/H]≤ −1 and thus(More)
Galaxy counts in the K band, (J −K)-colors, and apparent size distributions of faint galaxies in the Subaru Deep Field (SDF) down to K ∼ 24.5 were studied in detail. Special attention has been paid to take into account various selection effects including the cosmological dimming of surface brightness, to avoid any systematic bias which may be the origin of(More)