A5007045771- Astro and Planetary Science
- Planetary Science and Exploration
- Stellar, planetary, and galactic studies
- Gamma-ray bursts and supernovae
- Isotope Analysis in Ecology
- Geology and Paleoclimatology Research
- Astronomical Observations and Instrumentation
- Space Exploration and Technology
- Astrophysics and Star Formation Studies
- Space exploration and regulation
- Astronomy and Astrophysical Research
- Geophysics and Gravity Measurements
- Spacecraft and Cryogenic Technologies
- Advanced Optical Sensing Technologies
- Atmospheric Ozone and Climate
- Solar and Space Plasma Dynamics
- Inertial Sensor and Navigation
- Geological and Geochemical Analysis
- Calibration and Measurement Techniques
- Space Satellite Systems and Control
- Geomagnetism and Paleomagnetism Studies
- Laser-induced spectroscopy and plasma
- High-pressure geophysics and materials
- Space Science and Extraterrestrial Life
- GNSS positioning and interference
Chiba Institute of Technology
2017-2025
University of Occupational and Environmental Health Japan
2020-2025
Graduate School USA
2018
National Astronomical Observatory of Japan
2008-2017
Kobe University
2001-2017
National Institutes of Natural Sciences
2003-2016
Systèmes de Référence Temps-Espace
2014
University of Namur
2014
Hiroshima University
1996-2012
Waseda University
2010
Insights into the history of inner solar system can be derived from impact cratering record Moon, Mars, Venus, and Mercury size distributions asteroid populations. Old craters a unique period heavy bombardment that ended ∼3.8 billion years ago were made by asteroids dynamically ejected main belt, possibly due to orbital migration giant planets. The impactors past have distribution quite different belt but very similar near-Earth asteroids.
Hayabusa2 at the asteroid Ryugu Asteroids fall to Earth in form of meteorites, but these provide little information about their origins. The Japanese mission is designed collect samples directly from surface an and return them for laboratory analysis. Three papers this issue describe team's study near-Earth carbonaceous 162173 Ryugu, which spacecraft arrived June 2018 (see Perspective by Wurm). Watanabe et al. measured asteroid's mass, shape, density, showing that it a “rubble pile” loose...
On 27 August 2023 (UTC), a new organization for occultation observations in East Asia was formed, the International Occultation Timing Association/East (IOTA/EA). The goal of this is to promote and disseminate region make useful tool partner planetary exploration missions other scientific research. formation IOTA/EA triggered by stellar eclipse observation campaign (3200) Phaethon, which target JAXA DESTINY <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"...
We carry out a numerical study on the thermal behaviour of asteroid 3200 Phaethon, parent body Geminid meteor shower. Phaethon’s orbit is highly eccentric, with perihelion distance as small <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mstyle displaystyle="true" scriptlevel="0"> <mml:mrow> <mml:mn>0.14</mml:mn> <mml:mtext> </mml:mtext> </mml:mrow> <mml:mspace width="thinmathspace"/> <mml:mtext>au</mml:mtext> </mml:mstyle> </mml:math> ....
Rendezvous of the Japanese spacecraft Hayabusa with near-Earth asteroid 25143 Itokawa took place during interval September through November 2005. The onboard camera imaged solid surface this tiny (535 meters by 294 209 meters) a spatial resolution 70 centimeters per pixel, revealing diverse morphologies. Unlike previously explored asteroids, reveals both rough and smooth terrains. Craters generally show unclear Numerous boulders on Itokawa's suggest rubble-pile structure.
Context. In the past decade, more than one hundred asteroid models were derived using lightcurve inversion method. Measured by number of models, has become leading method for shape determination.
Quaoar is a classical Trans-Neptunian Object (TNO) with an area equivalent diameter of 1,100 km and orbital semi-major axis 43.3 astronomical units. Based on stellar occultations observed between 2018 2021, inhomogeneous ring (Q1R, Quaoar's first ring) was detected around this body. Aims. A new occultation by August 9th, 2022 aiming to improve shape models the physical parameters Q1R while searching for additional material Methods. The provided nine effective chords across Quaoar, pinning...
Abstract We report the detection of 239 trans-Neptunian objects discovered through ongoing New Horizons survey for distant minor bodies being performed with Hyper Suprime-Cam mosaic imager on Subaru Telescope. These were in images acquired either r 2 or recently commissioned EB- gri filter using shift and stack routines. Due to extremely high stellar density search region downstream spacecraft, new machine learning techniques had be developed manage false-positive rate bogus candidates...
We observed the L4 Jupiter Trojans (L4 JTs) swarm using Hyper Suprime-Cam attached to 8.2~m Subaru telescope on March 30, 2015 (UT). The survey covered $\sim$26~deg$^{2}$ of sky area near opposition and around ecliptic plane with 240-sec exposure time in $r$-band filter through entire survey. detected 631 JTs field detection limit $m_r$~=~24.4~mag. selected 481 objects absolute magnitude $H_r$~$<$~17.4 mag heliocentric distance $r$~$<$~5.5~au as an unbiased sample then used them estimate...
We review previously published and newly obtained crater size-frequency distributions in the inner solar system. These data indicate that Moon terrestrial planets have been bombarded by two populations of objects. Population 1, dominating at early times, had nearly same size distribution as present-day asteroid belt, produced heavily cratered surfaces with a complex, multi-sloped distribution. 2, since about 3.8-3.7 Ga, has near-Earth objects (NEOs), much lower impact flux, characterized...
We detected 51 faint Jovian Trojan asteroids in the L4 Lagrangian swarm survey observations near opposition and ecliptic using a wide-field mosaicked CCD camera on 8.2 m Subaru Telescope. report size distributions this paper. The surveyed sky area was about 3 deg2 located ∼30° longitude ahead of point. From trailed-image simulations hypothetical Trojans, we measured 90% complete detection limiting magnitudes for our chip-by-chip basis. varied by 0.4–0.5 mag between chips; therefore,...
Abstract— We obtained color images of near‐Earth asteroid 25143 Itokawa by the Hayabusa multiband imaging camera to characterize regional properties. Images were for whole disk from gate position (GP) and home (HP) at a spatial resolution 0.8–3.7 m/pixel. Whole‐disk spectra are adjusted telescopic data University Hawai'i's 88‐inch telescope using Eight Color Asteroid Survey (ECAS) system. The disk‐resolved measurements show large variations in three visible channels. present map an index...
A consensus view on the formation of planetesimals is now exposed to a threat, since recent numerical studies mechanical properties dust aggregates tend dispute conceptual picture that submicrometer-sized grains conglomerate into in protoplanetary disks. With advent precise laboratory experiments and extensive computer simulations interaction between elastic spheres comprising aggregates, we revisit model for tensile strength consisting small grains. In framework contact mechanics fracture...
Abstract In 2018, the near-Earth object (155140) 2005 UD (hereafter UD) experienced a close fly by of Earth. We present results from an observational campaign involving photometric, spectroscopic, and polarimetric observations carried out across wide range phase angles (0.°7–88°). also analyze archival NEOWISE observations. report absolute magnitude H V = 17.51 ± 0.02 mag albedo p 0.10 0.02. has been dynamically linked to Phaethon due their similar orbital configurations. Assuming surface...
Beyond the snow line of protoplanetary discs and inside dense core molecular clouds, temperature gas is low enough for water vapour to condense into amorphous ices on surface preexisting refractory dust particles. Recent numerical simulations laboratory experiments suggest that condensation promotes coagulation in such a cold region. However, simulations, cohesion materials often underestimated, while experiments, collides with surfaces at more frequent intervals compared real conditions....
Abstract This paper presents the result of first systematic investigation very small Main-Belt Asteroids (sub-km MBAs) using Subaru Prime-Focus Camera (Suprime-Cam) with an $8 \,\mathrm{K} \times 10 \,\mathrm{K}$ mosaic CCD array attached to 8.2m Telescope atop Mauna Kea, Hawaii. We call this survey SMBAS (Sub-km Asteroid Survey). Observations were carried out on 2001 February 22 and 25 (HST) a $\sim 3.0 \,\mathrm{deg}^{2}$ sky area near opposition ecliptic was searched. detected 1111 moving...
Abstract We have devised an automatic detection algorithm for unresolved moving objects, such as asteroids and comets. The uses many CCD images in order to detect very dark objects that are invisible on a single image. carried out trial observation investigate its usefulness, using 35-cm telescope. By the algorithm, we succeeded down about 21 mag. This will contribute significantly searches near-Earth solar-system astronomy.
Abstract Observation datasets acquired by the Hyper Suprime-Cam (HSC) on Subaru Telescope for NASA’s New Horizons mission target search were analyzed through a method devised JAXA. The makes use of Field Programmable Gate arrays and was originally used to detect fast-moving objects such as space debris or near-Earth asteroids. Here we present an application slow-moving Kuiper Belt Objects (KBOs) in observations. A cadence that takes continuous images one HSC field view half night fits well....
We present an analysis of a stellar occultation event caused by near-Earth asteroid (98943) 2001 CC21, upcoming flyby target in the Hayabusa2 extended mission, on March 5, 2023. To accurately determine asteroid's shape from diffraction-affected light curves, we developed novel data reduction technique named Diffracted Occultation's United Simulator for Highly Informative Transient Explorations (DOUSHITE). Using DOUSHITE-generated synthetic models, derived constraints CC21's shadow...
We constructed a new surface number density distribution model for Jovian Trojans around the L4 or L5 libration point of Jupiter. This is an empirical asymmetric Maxwellian-Gaussian type, derived from numerical integrations orbital motions actual Trojan asteroids point. With this model, in combination with observed densities obtained by Yoshida and Nakamura (2005, AJ, 130, 2900; 2008, PASJ, 60, 297), we estimate that total populations diameters $(D)&gt;$ 2 km are (6.3$\pm$1.0) $\times$...
We examined the size distributions of small L4 and L5 Jovian Trojan asteroids detected in Subaru main belt asteroid survey (SMBAS). This was first attempt to make a comparison distribution between Trojans for sizes ranging from $\sim1$ km $\sim10$km, using results systematic surveys. 51 62 0.7 13 diameter ($D$) (assuming an albedo 0.04). found that there is difference cumulative populations. The slopes population with 2 km${&lt;}D{&lt;}$5 5 km${&lt;}D{&lt;}$10 were...
The near-Earth asteroid 3200 Phaethon (1983 TB) is an attractive object not only from a scientific viewpoint but also because of JAXA's DESTINY+ target. rotational lightcurve and spin properties were investigated based on the data obtained in ground-based observation campaign Phaethon. We aim to refine lightcurves shape model using all available datasets via optical observation, as well our time-series 2017 apparition. Using eight 1-2-m telescopes imager, we acquired derived parameters...
Abstract Machine-learning techniques are widely applied in many modern optical sky surveys, e.g., Pan-STARRS1, PTF/iPTF, and the Subaru/Hyper Suprime-Cam survey, to reduce human intervention data verification. In this study, we have established a machine-learning-based real–bogus system reject false detections Subaru/Hyper-Suprime-Cam Strategic Survey Program (HSC-SSP) source catalog. Therefore, HSC-SSP moving object detection pipeline can operate more effectively due reduction of positives....