A5078836331- Solar and Space Plasma Dynamics
- Ionosphere and magnetosphere dynamics
- Geophysics and Gravity Measurements
- Geomagnetism and Paleomagnetism Studies
- Astro and Planetary Science
- Radio Astronomy Observations and Technology
- Stellar, planetary, and galactic studies
- Solar Radiation and Photovoltaics
- Planetary Science and Exploration
- Astrophysics and Cosmic Phenomena
- Earthquake Detection and Analysis
- Spacecraft Design and Technology
- Numerical Methods and Algorithms
- Advancements in PLL and VCO Technologies
- Digital Filter Design and Implementation
- Atmospheric Ozone and Climate
- Dark Matter and Cosmic Phenomena
- Gamma-ray bursts and supernovae
- Impact of Light on Environment and Health
- Astrophysics and Star Formation Studies
- Space exploration and regulation
- Historical Astronomy and Related Studies
- Pulsars and Gravitational Waves Research
- Statistical and numerical algorithms
- Cryptography and Residue Arithmetic
Nagoya University
2017-2025
National Institute for Space Research
2023
Shinshu University
2023
Research Organization of Information and Systems
2023
National Institute of Polar Research
2023
Earth and Space Research
2018-2020
National Solar Observatory
2014-2017
National Institute of Information and Communications Technology
2015-2017
National Astronomical Observatory of Japan
2013-2016
Misato Observatory
2013-2015
Abstract In 2024 May, the scientific community observed intense solar eruptions that resulted in a great geomagnetic storm and auroral extensions, highlighting need to document quantify these events. This study mainly focuses on their quantification. The source active region (AR; NOAA Active Region 13664) evolved from 113 2761 millionths of hemisphere between May 4 14. AR 13664’s magnetic free energy surpassed 10 33 erg 7, triggering 12 X-class flares 8–15. Multiple interplanetary coronal...
Abstract The dual spacecraft mission BepiColombo is the first joint between European Space Agency (ESA) and Japanese Aerospace Exploration (JAXA) to explore planet Mercury. was launched from Kourou (French Guiana) on October 20th, 2018, in its packed configuration including two spacecraft, a transfer module, sunshield. cruise trajectory long journey into inner heliosphere, it includes one flyby of Earth (in April 2020), Venus 2020 August 2021), six Mercury (starting before orbit insertion...
The ISWAT (International Space Weather Action Teams) heliosphere clusters H1 and H2 have a focus on interplanetary space its characteristics, especially the large-scale co-rotating transient structures impacting Earth. Solar wind stream interaction regions, generated by between high-speed solar originating in open coronal magnetic fields slower from closed fields, are regions of compressed plasma field followed streams that recur at ∼27 day rotation period. Short-term reconfigurations lower...
Coronal mass ejections (CMEs) cause various disturbances of the space environment; therefore, forecasting their arrival time is very important. However, accuracy hindered by limited CME observations in interplanetary space. This study investigates times at Earth forecasted three-dimensional (3D) magnetohydrodynamic (MHD) simulations based on scintillation (IPS) observations. In this system, CMEs are approximated as spheromaks with initial speeds. Ten MHD different speed tested, and density...
Abstract Computer-assisted tomography (CAT) for interplanetary scintillation (IPS) observations enables the determination of global distribution solar wind speed. We compared speeds derived from CAT analysis IPS between 1985 and 2019 with in situ conducted by near-Earth Ulysses spacecraft. From this comparison, we found that 2009–2019 were systematically higher than observations, whereas those period until 2008 good agreement observations. Further, discrepancy is improved changing power...
A new radio spectropolarimeter for solar observation has been developed at Tohoku University and installed on the Iitate Planetary Radio Telescope (IPRT) observatory in Fukushima prefecture, Japan. This system, named AMATERAS (the Assembly of Metric-band Aperture TElescope Real-time Analysis System), enables us to observe bursts frequency range between 150 500 MHz. The minimum detectable flux is less than 0.7 SFU with an integration time 10 ms a bandwidth 61 kHz. Both left right polarization...
Coronal mass ejections (CMEs) cause disturbances in the environment of Earth when they arrive at Earth. However, prediction arrival CMEs still remains a challenge. We have developed an interplanetary scintillation (IPS) estimation system based on global magnetohydrodynamic (MHD) simulation inner heliosphere to predict time CMEs. In this system, initial speed CME is roughly derived from white light coronagraph observations. Then, propagation calculated by MHD simulation. The IPS response...
Polar brightening of the Sun at radio frequencies has been studied for almost fifty years and yet a disagreement persists between solar atmospheric models observations. Some observations reported values much smaller than expected obtained from models, with discrepancies being particularly large millimeter wavelengths. New clues to calibrate can be advent Atacama Large Millimeter/submillimeter Array (ALMA) interferometer. In this work, we analyzed lower limit polar observed 100 230 GHz by...
Abstract Eruptive phenomena such as plasmoid ejections or jets are important features of solar activity and have the potential to improve our understanding dynamics atmosphere. Such often thought be signatures outflows expected in regions fast magnetic reconnection. The 304 Å EUV line helium, formed at around 10 5 K, is found a reliable tracer phenomena, but determination physical parameters from observations not straightforward. We observed ejection an X-ray bright point simultaneously...
In May 2024, the scientific community observed intense solar eruptions that resulted in an extreme geomagnetic storm and auroral extension, highlighting need to document quantify these events. This study mainly focuses on their quantification. The source active region (AR 13664) evolved from 113 2761 millionths of hemisphere between 4 14 2024. AR 13664's magnetic free energy surpassed 1033 erg 7 triggering 12 X-class flares. Multiple interplanetary coronal mass ejections (ICMEs) came out...
The first coordinated observations of an active region using ground-based radio telescopes and the Solar Terrestrial Relations Observatory (STEREO) satellites from different heliocentric longitudes were performed to study solar type-I noise storms. A storm was observed between 100 300 MHz during a period 2010 February 6 7. During this two STEREO located approximately 65° (ahead) −70° (behind) Sun–Earth line, which is well suited observe earthward propagating coronal mass ejections (CMEs)....
We derived the coronal magnetic field, plasma density, and temperature from observation of polarization intensity radio thermal free-free emission using Nobeyama Radioheliograph (NoRH) extreme ultraviolet (EUV) observations. observed a post-flare loop on west limb 11 April 2013. The line-of-sight field was circularly polarized by NoRH. measure were Atmospheric Imaging Assembly (AIA) onboard Solar Dynamics Observatory (SDO). used to estimate NoRH density larger than that determined AIA, which...
Abstract Various magnetohydrodynamic (MHD) waves have recently been detected in the solar corona and investigated intensively context of coronal heating seismology. In this Letter, we report first detection short-period propagating fast sausage mode a metric radio spectral fine structure observed with Assembly Metric-band Aperture Telescope Real-time Analysis System. Zebra patterns (ZPs) type-IV burst revealed quasi-periodic modulation frequency separation between adjacent stripes ZPs (Δ f...
We have developed a digital fast Fourier transform (FFT) spectrometer made of an analog-to-digital converter (ADC) and field-programmable gate array (FPGA). The base instrument has independent ADC FPGA modules, which allow us to implement different spectrometers in relatively easy manner. Two types been instrumented, one with 4.096 GS/s sampling speed 2048 frequency channels the other 2.048 32768 channels. signal processing these no dead time accumulated spectra are recorded external media...
Abstract We present the first high-resolution Atacama Large Millimeter/Submillimeter Array (ALMA) observations of a sunspot at wavelengths 1.3 and 3 mm, obtained during solar ALMA Science Verification campaign in 2015, compare them with predictions semi-empirical umbral/penumbral atmosphere models. For time, millimeter sunspots have resolved brightness structure chromospheric heights, where emission these is formed. find that umbra exhibits radically different appearance whereas penumbral...
We estimated the accuracy of coronal magnetic fields derived from radio observations by comparing them to potential field calculations and DEM measurements using EUV observations. line sight component polarization thermal bremsstrahlung in NOAA active region 11150, observed around 3:00 UT on February 3, 2011 Nobeyama Radioheliograph at 17 GHz. Because intensity GHz includes both chromospheric components, we extracted only measuring emission measure In addition, corona selecting loops weak...
The investigation of multi-spacecraft coordinated observations during the cruise phase BepiColombo (ESA/JAXA) are reported, with a particular emphasis on recently launched missions, Solar Orbiter (ESA/NASA) and Parker Probe (NASA). Despite some payload constraints, many instruments onboard operating its simultaneously covering wide range heliocentric distances (0.28 AU–0.5 AU). Hence, various spacecraft configurations combined in-situ remote sensing measurements from different spacecraft,...
Monitoring observations of solar microwave fluxes and their polarization began in Japan during the 1950s at Toyokawa Mitaka. At present (April 2022), monitoring continue with Nobeyama Radio Polarimeters (NoRP) campus National Astronomical Observatory (NAOJ). In this paper, we a brief history preceding those now carried out by NoRP. We then review obtained metadata. The datasets are publicly provided Solar Data Archive System (SDAS) operated Astronomy Center NAOJ, via http...
Solar radio type-I bursts were observed on 2011 January 26 by high resolution observations with the telescope AMATERAS in order to derive their peak flux distributions. We have developed a two-dimensional auto burst detection algorithm that can distinguish each element from complex noise storm spectra include numerous instances of frequency interference (RFI). This removes RFI applying moving median filter along axis. Burst and continuum components are distinguished maximum minimum search...
The brightness temperature of the radio free-free emission at millimeter range is an effective tool for characterizing vertical structure solar chromosphere. In this paper, we report on first single-dish observation a sunspot 85 and 115 GHz with sufficient spatial resolution resolving umbra using Nobeyama 45 m telescope. We used attenuation material, i.e. filter, to prevent saturation receivers. Considering contamination from plage by side-lobes, found that should be lower than quiet region....
Abstract Although solar activity may significantly impact the global environment and socioeconomic systems, mechanisms for eruptions subsequent processes have not yet been fully understood. Thus, modern society supported by advanced information systems is at risk from severe space weather disturbances. Project solar–terrestrial prediction (PSTEP) was launched to improve this situation through synergy between basic science research operational forecast. The PSTEP a nationwide collaboration in...
We investigate the upper chromosphere and transition region of sunspot umbra using radio brightness temperature at 34 GHz (corresponding to 8.8-mm observations) as observed by Nobeyama Radioheliograph (NoRH). Radio free-free emission in longer millimeter range is generated around region, its yields region's density distribution. use NoRH data applying Steer-CLEAN image synthesis. These analysis method enable us chromospheric structures with high spatial resolution sufficient visibilities....