A5002709189- Gamma-ray bursts and supernovae
- SAS software applications and methods
- Astro and Planetary Science
- Planetary Science and Exploration
- Astronomical Observations and Instrumentation
- Stellar, planetary, and galactic studies
- Isotope Analysis in Ecology
- Astrophysical Phenomena and Observations
- Astrophysics and Star Formation Studies
- Astrophysics and Cosmic Phenomena
- Particle Detector Development and Performance
- Astronomy and Astrophysical Research
- Spacecraft and Cryogenic Technologies
- Atmospheric Ozone and Climate
- Pulsars and Gravitational Waves Research
- Geology and Paleoclimatology Research
- Nuclear Physics and Applications
- Solar and Space Plasma Dynamics
- Monoclonal and Polyclonal Antibodies Research
- Space Exploration and Technology
- Ionosphere and magnetosphere dynamics
- Click Chemistry and Applications
- Physics of Superconductivity and Magnetism
- High-pressure geophysics and materials
- Chemical Synthesis and Analysis
Japan Spaceguard Association
2022-2024
Kyoto University
2010-2023
Okayama University
2018-2023
Kumamoto Medical Center
2022
The University of Tokyo
2021
Japan Aerospace Exploration Agency
2021
National Astronomical Observatory of Japan
2009-2019
Kumamoto University
2019
Bay Institute
2018
National Institute of Technology, Suzuka College
2007-2018
The first detected gravitational wave from a neutron star merger was GW170817. In this study, we present J-GEM follow-up observations of SSS17a, an electromagnetic counterpart SSS17a shows 2.5-mag decline in the $z$-band 1.7 days to 7.7 after merger. Such rapid is not comparable with supernovae light curves at any epoch. color also evolves rapidly and becomes redder for later epochs; $z-H$ changed by approximately 2.5 mag period 0.7 days. evolution both optical brightness are consistent...
Abstract We present the results of an unbiased asteroid survey in mid-infrared wavelength region with Infrared Camera (IRC) on board Japanese infrared satellite AKARI. About 20% point source events recorded AKARI All-Sky Survey observations are not used for IRC Point Source Catalog (IRC-PSC) its production process because a lack multiple detection by position. Asteroids, which moving objects celestial sphere, remain these ``residual events''. identify asteroids out residual matching them...
We present early phase observations in optical and near-infrared wavelengths for the extremely luminous Type Ia supernova (SN Ia) 2009dc. The decline rate of light curve is $\Delta m_{15}(B)=0.65\pm 0.03$, which one slowest among SNe Ia. peak $V$-band absolute magnitude $M_{V}=-19.90\pm 0.15$ mag even if host extinction $A_{V}=0$ mag. It reaches $M_{V}=-20.19\pm 0.19$ $A_{V}=0.29$ as inferred from observed Na {\sc i} D line absorption host. Our $JHK_{s}$-band photometry shows that SN most...
Long-duration Gamma-Ray Bursts (GRBs) are an extremely rare outcome of the collapse massive stars, and typically found in distant Universe. Because its intrinsic luminosity ($L\sim 3 \times 10^{53}$ erg s$^{-1}$) relative proximity ($z=0.34$), GRB 130427A was a unique event that reached highest fluence observed gamma-ray band. Here we present comprehensive multiwavelength view with Swift, 2-m Liverpool Faulkes telescopes by other ground-based facilities, highlighting evolution burst emission...
Context. Near-Earth asteroid 162173 (1999 JU3) is a potential flyby and rendezvous target for interplanetary missions because of its easy-to-reach orbit. The physical thermal properties the are relevant establishing scientific mission goals also important in context near-Earth object studies general.
ABSTRACT An overview of the Seimei telescope, a 3.8 m optical infrared telescope located on Mt. Chikurinji in Okayama prefecture Japan, is presented. segmented-mirror whose primary mirror consists 18 petal-shaped segments. The tube supporting thin segmented mirrors structurally incorporated within large arc-rails providing elevation axis. has light-weight homologous structure designed with genetic algorithm. total weight tube, including 1.4-ton optics, only 8 tons. By virtue its light...
Context. The Hayabusa2 spacecraft launched by Japan Aerospace Exploration Agency has been conducting observations of the asteroid (162173) Ryugu since June 2018. Telescopic Optical Navigation Camera (ONC-T) onboard obtained thousands images under a variety illumination and viewing conditions. Aims. Our objective is to examine validate camera calibration, derive photometric correction for creating global albedo maps, interpret modeling results characterize surface Ryugu. Methods. We observed...
We present an analysis of the albedo properties main belt asteroids detected by All-Sky Survey infrared satellite AKARI. The characteristics 5120 survey, including their sizes and albedos, were cataloged in Asteroid Catalog Using AKARI (AcuA). Size measurements based on Standard Thermal Model, using inputs fluxes absolute magnitudes. Main asteroids, which account for 4722 AcuA have semimajor axes 2.06 to 3.27 AU. provides a complete data set all brighter than magnitude H < 10.3, corresponds...
We present optical (g', R_c, and I_c) to near-infrared (J) simultaneous photometric observations for a primary transit of GJ3470b, Uranus-mass transiting planet around nearby M dwarf, by using the 50-cm MITSuME telescope 188-cm telescope, both at Okayama Astrophysical Observatory. From these data, we derive planetary mass, radius, density as 14.1 \pm 1.3 M_earth, 4.32^{+0.21}_{-0.10} R_earth, 0.94 0.12 g cm^{-3}, respectively, thus confirming low that was reported Demory et al. based on...
The JAXA Hayabusa-2 mission was approved in 2010 and launched on December 3, 2014. spacecraft will arrive at the near-Earth asteroid 162173 Ryugu 2018 where it perform a survey, land obtain surface material, then depart Dec 2019 return to Earth 2020. We observed with Herschel Space Observatory Apr 2012 far-IR thermal wavelengths, supported by several ground-based observations optical lightcurves. reanalysed previously published Subaru-COMICS AKARI-IRC merged them Spitzer-IRS data set. In...
An unexpected outburst was observed around (596) Scheila in 2010 December. We soon after the impact using ground-based telescopes. succeeded detection of a faint linear tail 2011 February, which provides clue to determine dust ejection date. It is found that particles ranging from 0.1–1 μm 100 were ejected into interplanetary space impulsively on December 3.5 ±1.0 day. The ejecta mass estimated be (1.5–4.9)×108 kg, suggesting an equivalent 500–800 m diameter crater excavated by event. also...
We investigated the magnitude–phase relation of (162173) 1999 JU3, a target asteroid for JAXA Hayabusa 2 sample return mission. initially employed International Astronomical Union's H–G formalism but found that it fits less well using single set parameters. To improve inadequate fit, we two photometric functions: Shevchenko and Hapke functions. With function, exhibits linear behavior in wide phase angle range (α = 5°–75°) shows weak nonlinear opposition brightening at α < 5°, providing more...
Context. The JAXA Hayabusa2 mission will perform the first ever sample return from a primitive asteroid. target near-Earth asteroid (162173) Ryugu be reached in mid-2018 and its samples returned to Earth by end of 2020. Aims. We want improve current knowledge compositional rotational properties Ryugu, which are still presenting some uncertainties that might affect operations scientific return. Methods. acquired high-quality photometric time-series data with FORS2 instrument at Very Large...
We report observations of the Type Iax supernova (SN Iax) 2012Z at optical and near-infrared (NIR) wavelengths from immediately after explosion until ∼260 days maximum luminosity using Optical Infrared Synergetic Telescopes for Education Research Target-of-Opportunity program Subaru Telescope. found that NIR light curve evolutions color are similar to those SNe 2005hk 2008ha. The absolute magnitudes ( mag mag) rate decline (m15(B) very SN mag, m15(B) 1.6 mag), yet differ significantly 2008ha...
Strange-looking dust cloud around asteroid (596) Scheila was discovered on 2010 December 11.44-11.47. Unlike normal cometary tails, it consisted of three tails and faded within two months. We constructed a model to reproduce the morphology based laboratory measurement high velocity impacts dynamics. As result, we succeeded in reproduction peculiar by an impact-driven ejecta plume consisting impact cone downrange plume. Assuming angle 45 deg, our suggests that decameter-sized collided with...
We present optical and near-infrared multi-band linear polarimetry of the highly reddened Type Ia supernova (SN) 2014J that appeared in M82. SN exhibits large polarization at shorter wavelengths, e.g., 4.8% B band, which decreases rapidly longer while position angle remains approximately 40° over observed wavelength range. These polarimetric properties suggest is likely predominantly caused by interstellar dust within Further analysis shows peaks a wavelengths much than those obtained for...
Abstract The Kiso Supernova Survey (KISS) is a high-cadence optical wide-field supernova (SN) survey. primary goal of the survey to catch very early light SN, during shock breakout phase. Detection SN breakouts combined with multi-band photometry obtained other facilities would provide detailed physical information on progenitor stars SNe. performed using 2 $_{.}^{\circ}$2 × field-of-view instrument 1.05-m Schmidt telescope, Wide Field Camera (KWFC). We take 3-min exposure in g-band once...
Two extremely red main-belt asteroids: 203 Pompeja and 269 Justitia, were identified from combined visible near-infrared spectroscopic observations collected at the IRTF SAO observatories. These two asteroids have a redder spectral slope than any other D-type body, which are reddest objects in asteroid belt, similar to RR IR-class found outer Solar System among trans-Neptunian Centaurs. Spectroscopic results suggest presence of complex organic materials on surface layer these asteroids,...
We present 5 new transit light curves of GJ 1214b taken in BJHKs-bands. Two transits were observed B-band using the Suprime-Cam and FOCAS instruments onboard Subaru 8.2m telescope, one was done JHKs-bands simultaneously with SIRIUS camera on IRSF 1.4m telescope. MCMC analyses show that planet-to-star radius ratios are, Rp/Rs = 0.11651 \pm 0.00065 (B-band, Subaru/Suprime-Cam), 0.11601 0.00117 Subaru/FOCAS), 0.11654 0.00080 (J-band, IRSF/SIRIUS), 0.11550 ^{+0.00142}_{-0.00153} (H-band, 0.11547...
We present our optical follow-up observations to search for an electromagnetic counterpart of the first gravitational wave source GW150914 in framework Japanese collaboration Gravitational ElectroMagnetic (J-GEM), which is observing group utilizing and radio telescopes Japan, as well those New Zealand, China, South Africa, Chile, Hawaii. carried out a wide-field imaging survey with Kiso Wide Field Camera (KWFC) on 1.05-m Schmidt telescope Japan galaxy-targeted Tripole5 B&C 61-cm Zealand....
Abstract We present optical observations of the Type Ia supernova (SN) 2019ein, starting two days after estimated explosion date. The spectra and light curves show that SN 2019ein belongs to a high-velocity (HV) broad-line group with relatively rapid decline in (Δ m 15 ( B ) = 1.36 ± 0.02 mag) short rise time (15.37 0.55 days). Si ii λ 6355 velocity, associated photospheric component but not detached feature, reached ∼20,000 km s −1 12 before -band maximum. line however, decreased very...
Context. Sunlight scattered from the surface of an airless body is generally partially polarized, and corresponding polarization state includes information about scattering surface, such as albedo, grain sizes, composition, taxonomic types. Most polarimetric studies on bodies thus far have focused optical wavelengths ( λ ≲ 1 µm). Aims. We conducted polarimetry two large bodies, Dawn mission targets (1) Ceres (4) Vesta, in near-infrared region. further investigated change phase curves over...
This work explores characteristics of the negative polarization branch (NPB), which occurs in scattered light from rough surfaces, with particular focus on effects fine particles. Factors such as albedo, compression, roughness, and refractive index are considered to determine their influence NPB. study compiles experimental data lunar observations derive insights a wide array literature. Employing our proposed methodology, we estimate representative grain sizes surface be D ~ 1–2 µm, ≲ 2–4...