436 citations · 918 across the 23 of their papers we have counts for
23 papers
A fast-filament eruption observed in the H spectral line. I. Imaging spectroscopy diagnostic
Denis P. Cabezas, Kiyoshi Ichimoto, Ayumi Asai +4
Context. Solar filament eruptions usually appear to occur in association with the sudden explosive release of magnetic energy accumulated in long-lived arched magnetic structures.…
Thermodynamic properties of small flares in the quiet Sun observed by H and EUV: plasma motion of the chromosphere and time evolution of temperature/emission measure
Yuji Kotani, Takako T. Ishii, Daiki Yamasaki +4
Small flares frequently occur in the quiet Sun. Previous studies have noted that they share many common characteristics with typical solar flares in active regions. However, their…
Unified Relationship between Cold Plasma Ejections and Flare Energies Ranging from Solar Microflares to Giant Stellar Flares
Yuji Kotani, Kazunari Shibata, Takako T. Ishii +4
We often find spectral signatures of chromospheric cold plasma ejections accompanied by flares in a wide range of spatial scales in the solar and stellar atmospheres. However, the…
Small-scale Turbulent Motion of the Plasma in a Solar Filament as the Precursor of Eruption
Daikichi Seki, Kenichi Otsuji, Hiroaki Isobe +5
A filament, a dense cool plasma supported by the magnetic fields in the solar corona, often becomes unstable and erupts. It is empirically known that the filament often demonstrate…
Relationship between three-dimensional velocity of filament eruptions and CME association
Daikichi Seki, Kenichi Otsuji, Takako T. Ishii +2
It is widely recognised that filament disappearances or eruptions are frequently associated with Coronal Mass Ejections (CMEs). Since CMEs are a major source of disturbances of the…
A Three-Dimensional Velocity of an Erupting Prominence Prior to a Coronal Mass Ejection
Maria V. Gutierrez, Kenichi Otsuji, Ayumi Asai +10
We present a detailed three-dimensional (3D) view of a prominence eruption, coronal loop expansion, and coronal mass ejections (CMEs) associated with an M4.4 flare that occurred on…
Synoptic solar observations of the Solar Flare Telescope focusing on space weather
Yoichiro Hanaoka, Takashi Sakurai, Ken'ichi Otsuji +2
The solar group at the National Astronomical Observatory of Japan is conducting synoptic solar observations with the Solar Flare Telescope. While it is a part of a long-term solar…
SMART/SDDI Filament Disappearance Catalogue
Daikichi Seki, Kenichi Otsuji, Takako T. Ishii +8
This paper describes a new SMART/SDDI Filament Disappearance Catalogue, in which we listed almost all the filament disappearance events that the Solar Dynamics Doppler Imager (SDDI…
Revisiting Kunitomo's Sunspot Drawings during 1835-1836 in Japan
Masashi Fujiyama, Hisashi Hayakawa, Tomoya Iju +7
We revisit the sunspot drawings made by the Japanese astronomer Kunitomo Toubei during 1835-1836 and recount the sunspot group number for each image. There are two series of drawin…
Small-scale motions in solar filaments as the precursors of eruptions
Daikichi Seki, Kenichi Otsuji, Hiroaki Isobe +3
Filaments, the dense cooler plasma floating in the solar corona supported by magnetic fields, generally exhibit certain activations before they erupt. In our previous study (Seki e…
Space Weather Prediction from the Ground: Case of CHAIN
Daikichi Seki, Satoru Ueno, Hiroaki Isobe +5
In this article, we insist on the importance and the challenges of the prediction of solar eruptive phenomena including flares, coronal mass ejections (CME), and filament eruptions…
Increase in the amplitude of line-of-sight velocities of the small-scale motions in a solar filament before eruption
Daikichi Seki, Kenichi Otsuji, Hiroaki Isobe +3
We present a study on the evolution of the small scale velocity field in a solar filament as it approaches to the eruption. The observation was carried out by the Solar Dynamics Do…
"Dandelion" Filament Eruption and Coronal Waves Associated with a Solar Flare on 2011 February 16
Denis P. Cabezas, Lurdes M. Martínez, Yovanny J. Buleje +11
Coronal disturbances associated with solar flares, such as H Moreton waves, X-ray waves, and extreme ultraviolet (EUV) coronal waves are discussed herein in relation to magnetoh…
Statistical Analysis of Current Helicity and Twist in Solar Active Regions over the Phases of the Solar Cycle Using the Spectro-Polarimeter Data of Hinode
Kenichi Otsuji, Takashi Sakurai, Kirill Kuzanyan
Current helicity and twist of solar magnetic fields are important quantities to characterize the dynamo mechanism working in the convection zone of the Sun. We have carried out a s…
Morphological study of penumbral formation
Reizaburo Kitai, Hiroko Watanabe, Ken'ichi Otsuji
Penumbrae are known to be area of mainly horizontal magnetic field surrounding umbrae of relatively large and mature sunspots. In this paper, we observationally studied the formati…
Statistical Study on the Nature of Solar Flux Emergence
Kenichi Otsuji, Reizaburo Kitai, Kiyoshi Ichimoto +1
We studied 101 flux emergence events ranging from small ephemeral regions to large emerging flux regions which were observed with Hinode Solar Optical Telescope filtergram. We inve…
Ca II K Spectral Study of an Emerging Flux Region using Domeless Solar Telescope in Hida Observatory
Kenichi Otsuji, Reizaburo Kitai, Takuma Matsumoto +5
A cooperative observation with Hida observatory and Hinode satellite was performed on an emerging flux region. The successive Ca II K spectro-heliograms of the emerging flux region…
Spicule Dynamics over Plage Region
Tetsu Anan, Reizaburo Kitai, Tomoko Kawate +14
We studied spicular jets over a plage area and derived their dynamic characteristics using Hinode Solar Optical Telescope (SOT) high-resolution images. The target plage region was…
Observations of Chromospheric Anemone Jets with Hinode SOT and Hida Ca II Spectroheliogram
Satoshi Morita, Kazunari Shibata, Satoru Ueno +3
We present the first simultaneous observations of chromospheric "anemone" jets in solar active regions with Hinode SOT Ca II H broadband filetergram and Ca II K spetroheliogram on…
Chromospheric Anemone Jets as Evidence of Ubiquitous Reconnection
Kazunari Shibata, Tahei Nakamura, Takuma Matsumoto +19
The heating of the solar chromosphere and corona is a long-standing puzzle in solar physics. Hinode observations show the ubiquitous presence of chromospheric anemone jets outside…
Giant Chromospheric Anemone Jet Observed with Hinode and Comparison with Magnetohydrodynamic Simulations: Evidence of Propagating Alfven Waves and Magnetic Reconnection
N. Nishizuka, M. Shimizu, T. Nakamura +4
Hinode discovered a beautiful giant jet with both cool and hot components at the solar limb on 2007 February 9. Simultaneous observations by the Hinode SOT, XRT, and TRACE 195 sate…
Umbral Fine Structures in Sunspots Observed with Hinode Solar Optical Telescope
Reizaburo Kitai, Hiroko Watanabe, Tahei Nakamura +15
High resolution imaging observation of a sunspot umbra was done with Hinode Solar Optical Telescope (SOT). Filtergrams in wavelengths of blue and green continuum were taken during…
Small Scale Magnetic Flux Emergence Observed with Hinode/Solar Optical Telescope
Kenichi Otsuji, Kazunari Shibata, Reizaburo Kitai +14
We observed small scale magnetic flux emergence in a sunspot moat region by the Solar Optical Telescope (SOT) aboard the Hinode satellite. We analyzed filtergram images observed in…