A5060808565- Solar and Space Plasma Dynamics
- Ionosphere and magnetosphere dynamics
- Stellar, planetary, and galactic studies
- Astro and Planetary Science
- Geophysics and Gravity Measurements
- Geomagnetism and Paleomagnetism Studies
- Solar Radiation and Photovoltaics
- Adaptive optics and wavefront sensing
- Astrophysics and Cosmic Phenomena
- Magnetic confinement fusion research
- solar cell performance optimization
- Atmospheric Ozone and Climate
- Gamma-ray bursts and supernovae
- Radio Astronomy Observations and Technology
- Earthquake Detection and Analysis
- Atomic and Subatomic Physics Research
- Soil Moisture and Remote Sensing
- Calibration and Measurement Techniques
- Impact of Light on Environment and Health
- CCD and CMOS Imaging Sensors
- Optical Wireless Communication Technologies
- Optical Systems and Laser Technology
- Spacecraft Design and Technology
- Pulsars and Gravitational Waves Research
- Astronomy and Astrophysical Research
National Astronomical Observatory of Japan
2015-2024
The University of Tokyo
2020
The Graduate University for Advanced Studies, SOKENDAI
2018
Subaru (Japan)
2012
Misato Observatory
1993-2008
Purple Mountain Observatory
2007
Astronomical Observatory
1999-2005
Kyoto University
1986-1989
A new 17-GHz radio interferometer dedicated for solar observations was constructed in two years at Nobeyama, Nagano. It consists of eighty-four 80-cm-diameter antennas arranged a tee-shaped array extending 490 m east-west and 220 north-south directions. Since late June 1992, full-disk images the Sun have been observed 8 h every day. The spatial resolution is 10" temporal 1 s also 50 ms selected events. Every 10 correlator data are synthesized into real time displayed on monitor screen....
We derive the plage area evolution over last 12 solar cycles employing data from all Ca II K archives available publicly in digital form known to us, including several as yet unexplored archives. analyse more than 290,000 full-disc observations 43 datasets spanning period 1892-2019. All images were consistently processed with an automatic procedure that performs photometric calibration (if needed) and limb-darkening compensation. The processing also accounts for artefacts plaguing many of...
We report the results of our investigation a giant eruptive prominence (initial mass ~6×1016 g) using microwave, X-ray, and white-light observations. The erupted from northwest limb Sun on 1994 April 5. speed was only ~70 km s−1 when it reached height ~0.5 R above solar surface. In X-rays, large region with reduced X-ray emission observed enveloping initial location extending to much larger heights. At bottom this depletion beneath prominence, an arcade formed, progressively spreading south...
We compare the substructures of 1997 February 07 coronal mass ejection (CME) observed near Sun with a corresponding event in interplanetary medium to determine origin magnetic clouds (MCs). find that eruptive prominence core CME may not directly become cloud as suggested by some authors and it might instead ”pressure pulse” following cloud. substantiate our conclusions using time arrival, size composition estimates CME‐MC obtained from ground based, SOHO WIND observations.
We analyze the three-dimensional geometry of solar flares that show so-called interacting flare loops in soft X-ray, hard and radio emission, as previously identified by Hanaoka Nishio. The two appear brightest after are assumed to represent outcome a quadrupolar magnetic reconnection process, during which connectivity polarities is exchanged between four loop footpoints. parameterize involved field lines with circular segments, additionally constrained geometric condition pre-reconnection...
Context. Full-disc observations of the Sun in H α line provide information about solar chromosphere, and particular, filaments, which are dark elongated features that lie along magnetic field polarity-inversion lines. This makes them important for studies magnetism. Because full-disc have been performed at various sites since second half 19th century, with regular photographic data having started beginning 20th they an invaluable source on past Aims. We derive accurate filaments from...
We present observations of a coronal mass ejection (CME) associated with an eruptive prominence during 1998 June 21-22 by LASCO (Large Angle Spectroscopic Coronagraph) aboard SOHO (Solar and Heliospheric Observatory). Various features in the three-part structured, white-light CME as observed LASCO-C2 C3 coronagraphs were compared other wavelengths, for example, Fe XIV X emission lines obtained from C1, Hα Helio-Research at 17 GHz Nobeyama Radioheliograph. have investigated conditions several...
We studied the fast temporal variations in brightness of radio and hard X-ray sources three double-loop flares. In such flares, main radio/hard source is located near to one footpoints a large overlying loop, where small, newly emerging loop appears two loops interact, remote at another footpoint loop. The following results were obtained from analysis: (1) basically show correlated fluctuation, but rapid fluctuation lags behind that for about 500 ms. This result evidence...
The National Astronomical Observatory of Japan started regular synoptic solar observations about 100 years ago. At the beginning, Ca K spectroheliograms and white-light photographs were taken, various other types have been added. These historical data digitized are now open at our web site (http://solarwww.mtk.nao.ac.jp/en/solarobs.html). Currently we operating high-resolution imaging in Hα line, green continuum, G-band. Besides kinds observations, magnetic field measurements carried out for...
We report on the observations of an X-ray coronal mass ejection (CME) with its three part structure: frontal loop, cavity, and eruptive prominence core. The core was observed in microwaves, loop X-rays. A volume much larger than that occupied by seems to be affected eruption. Formation arcade structure also beneath erupting prominence. enhancement at persisted for several hours similar long decay events. At apex there a bright knot, which we interpret as reconnection region from filament...
view Abstract Citations (37) References (13) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS A Flare Caused by Interacting Coronal Loops Hanaoka, Yoichiro The observation of a flare on 1992 July 15 with the Soft X-ray Telescope (SXT) board Yohkoh satellite shows that energy buildup in corona was caused increasing shear magnetic field due to photospheric flow and occurred through interaction sheared coronal loops. About 24 hr before flare, loops were only...
Abstract Coronal jets, which extend from the solar surface to beyond 2 R ⊙ , were observed in polar coronal hole regions during total eclipse on 2017 August 21. In a time-series of white-light images corona spanning 70 minutes taken with our multi-site observations this eclipse, six jets found as narrow structures upwardly ejected an apparent speed about 450 km s −1 plumes. On other hand, extreme-ultraviolet (EUV) Atmospheric Image Assembly Solar Dynamics Observatory show that all preceded...
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...
Abstract An infrared spectro-polarimeter installed on the Solar Flare Telescope at Mitaka headquarters of National Astronomical Observatory Japan is described. The new observes full Sun via slit scans performed two wavelength bands, one near 1565 nm for a Zeeman-sensitive spectral line Fe i and other 1083 He Si lines. Stokes profiles are recorded; lines give information photospheric vector magnetic fields, helium suitable deriving chromospheric fields. detector we using an InGaAs camera with...