The Solar Optical Telescope for the Hinode Mission: An Overview

Tsuneta, S.; Ichimoto, Kiyoshi; Katsukawa, Y.; Nagata, Shinji; Otsubo, Masahisa; Shimizu, Toshifumi; Suematsu, Y.; Nakagiri, M.; Noguchi, Motokazu; Tarbell, T. D.; Title, A. M.; Shine, R. A.; Rosenberg, W. J.; Hoffmann, C.; Jurcevich, B.; Kushner, G.; Levay, M.; Lites, B. W.; Elmore, D.; Matsushita, Tadashi; Kawaguchi, Noboru; Saitō, Hideo; Izumi, Mitsuru; Hill, L. D.; Owens, J. K.

doi:10.1007/s11207-008-9174-z

Cited by 1,188 publications

(842 citation statements)

References 33 publications

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“…The Ca ii H images do not purely represent the chromosphere, but contain contributions from both the upper photosphere and lower chromosphere. These observations were carried out by the Broad-band Filter Imager (BFI) of the Solar Optical Telescope (SOT, Tsuneta et al 2008) on board Hinode (Kosugi et al 2007). Data sequences were captured every day from 09:00 UT to 12:00 UT with an average time cadence of 120 s (with some jumps in the data sequences).…”

Section: Hinode G-band and Ca II H Imagesmentioning

confidence: 99%

Horizontal flow fields observed in Hinode G-band images

Verma

Balthasar

Deng

et al. 2012

A&A

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Context. Generation and dissipation of magnetic fields is a fundamental physical process on the Sun. In comparison to flux emergence and the initial stages of sunspot formation, the demise of sunspots still lacks a comprehensive description. Aims. The evolution of sunspots is most commonly discussed in terms of their intensity and magnetic field. Here, we present additional information about the three-dimensional flow field in the vicinity of sunspots towards the end of their existence. Methods. We present a subset of multi-wavelengths observations obtained with the Japanese Hinode mission, the Solar Dynamics Observatory (SDO), and the Vacuum Tower Telescope (VTT) at Observatorio del Teide, Tenerife, Spain during the time period 2010 November 18−23. Horizontal proper motions were derived from G-band and Ca ii H images, whereas line-of-sight velocities were extracted from VTT echelle Hα λ656.28 nm spectra and Fe i λ630.25 nm spectral data of the Hinode/Spectro-Polarimeter, which also provided three-dimensional magnetic field information. The Helioseismic and Magnetic Imager on board SDO provided continuum images and line-of-sight magnetograms, in addition to the high-resolution observations for the entire disk passage of the active region. Results. We perform a quantitative study of photospheric and chromospheric flow fields in and around decaying sunspots. In one of the trailing sunspots of active region NOAA 11126, we observe moat flow and moving magnetic features (MMFs), even after its penumbra had decayed. We also detect a superpenumbral structure around this pore. We find that MMFs follow well-defined, radial paths from the spot all the way to the border of a supergranular cell surrounding the spot. In contrast, flux emergence near the other sunspot prevents the establishment of similar well ordered flow patterns, which could be discerned around a tiny pore of merely 2 Mm diameter. After the disappearance of the sunspots/pores, a coherent patch of abnormal granulation remained at their location, which was characterized by more uniform horizontal proper motions, low divergence values, and smaller photospheric Doppler velocities. This region, thus, differs significantly from granulation and other areas covered by G-band bright points. We conclude that this peculiar flow pattern is a signature of sunspot decay and the dispersal of magnetic flux.

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Section: Hinode G-band and Ca II H Imagesmentioning

confidence: 99%

Horizontal flow fields observed in Hinode G-band images

Verma

Balthasar

Deng

et al. 2012

A&A

Self Cite

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“…Its location as well as several transient brightenings preceding the flare were visible already around 12:00 UT. These transient brightenings occured mostly along a long, ribbon-like structure apparent in the Hinode/Solar Optical Telescope (SOT, Tsuneta et al 2008) Ca II H observations, in the IRIS 1400Å slit-jaw images, or in the SDO/AIA 304Å channel. This ribbon-like structure corresponded to the footpoints of hot Fe XVIII loops observed in the AIA 94Å band (Fig.…”

Section: Context Observationsmentioning

confidence: 96%

GREGOR observations of a small flare above a sunspot

Sobotka¹,

Dudík²,

Denker

et al. 2015

Proc. IAU

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Abstract.A small flare ribbon above a sunspot umbra in active region 12205 was observed on November 7, 2014, at 12:00 UT in the blue imaging channel of the 1.5-m GREGOR telescope, using a 0.1 nm Ca II H interference filter. Context observations from SDO/AIA, Hinode/SOT, and IRIS show that the ribbon is a part of a larger one that extends through the neighboring positive polarities and also participates in several other flares within the active region. A 140 second long time series of Ca II H images was reconstructed by means of the Multi-Frame Blind Deconvolution method, giving the respective spatial and temporal resolutions of 0".1 and 1 s. Light curves and horizontal velocities of small-scale bright knots in the observed flare ribbon were measured. Some knots are stationary but three move along the ribbon with speeds of 7-11 km s −1 . Two of them move in the opposite direction and exhibit highly correlated intensity changes, providing evidence for the presence of slipping reconnection at small spatial scales.

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“…We chose the M-and X-class flares because WLFs are usually associated with relatively large flares, and 721 of these occurred among the 11, 387 events. We selected events that were observed using the Solar Optical Telescope (SOT) [23,24,25,26] onboard Hinode in the visible continuum bands (G-band, blue, green, and red) in the flare-observation mode (taking WL images every 20 s for each band); 101 were detected. Then, we performed statistical analyses of the hard X-ray data observed by the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) [27].…”

Section: Event Selectionmentioning

confidence: 99%

Capability of the accelerated protons as the origin of white-light emission of solar flare

Watanabe¹,

Masuda²,

Ohno³

2017

Proceedings of 35th International Cosmic Ray Conference — PoS(ICRC2017)

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In association with strong solar flares, we sometimes observe enhancements of visible continuum radiation, which is known as a "white-light flare". As most white-light (WL) events show close correlations in time and location with hard X-rays and/or radio emission, there is some consensus that WL emission originates from accelerated particles, especially non-thermal electrons. One model proposes that WL is emitted near the photosphere; however, non-thermal electrons are thermalized in the chromosphere and cannot reach the photosphere. Thus, there is a problem: how can the energy of non-thermal electrons − and/or other accelerated particles such as high-energy protons − propagate to the photosphere and produce WL emission? In the present study, we investigate the possibility that accelerated protons may produce the WL emission of solar flares. We found 51 WL events observed by Hinode/SOT. Among them, gamma-rays with energies greater than 1 MeV were observed only in the X1.8-class flare on October 23, 2012 and in the M7.9-class flare on June 25, 2015. Focusing on these flare events, we compare the energetics of WL emission and of accelerated ion fluxes. We find that it is difficult for accelerated ions to provide sufficient energy to account for WL emission.

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The Solar Optical Telescope for the Hinode Mission: An Overview

Cited by 1,188 publications

References 33 publications

Horizontal flow fields observed in Hinode G-band images

Horizontal flow fields observed in Hinode G-band images

GREGOR observations of a small flare above a sunspot

Capability of the accelerated protons as the origin of white-light emission of solar flare

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