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Freeland, S.; Handy, B. N.

doi:10.1023/a:1005038224881

Cited by 655 publications

(408 citation statements)

References 2 publications

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“…The data are not calibrated at this step but are converted to "photon events" or counts and are calibrated at a later stage in the processing. See Freeland & Handy (1998) for a description of the Solar Software-SSW-used in the analysis of these data.…”

Section: Observationsmentioning

confidence: 99%

Transition Region Abundance Measurements During Impulsive Heating Events

Warren

Brooks

Doschek

et al. 2016

ApJ

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It is well established that elemental abundances vary in the solar atmosphere and that this variation is organized by first ionization potential (FIP). Previous studies have shown that in the solar corona, low-FIP elements such as Fe, Si, Mg, and Ca, are generally enriched relative to high-FIP elements such as C, N, O, Ar, and Ne. In this paper we report on measurements of plasma composition made during impulsive heating events observed at transition region temperatures with the Extreme Ultraviolet Imaging Spectrometer (EIS) on Hinode. During these events the intensities of O IV, V, and VI emission lines are enhanced relative to emission lines from Mg V, VI, and VII and Si VI and VII, and indicate a composition close to that of the photosphere. Long-lived coronal fan structures, in contrast, show an enrichment of low-FIP elements. We conjecture that the plasma composition is an important signature of the coronal heating process, with impulsive heating leading to the evaporation of unfractionated material from the lower layers of the solar atmosphere and higher-frequency heating leading to long-lived structures and the accumulation of low-FIP elements in the corona.

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Section: Observationsmentioning

confidence: 99%

Transition Region Abundance Measurements During Impulsive Heating Events

Warren

Brooks

Doschek

et al. 2016

ApJ

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“…The region was scanned with a spatial step of about 0.3 and image scale of 0.32 pixel −1 . The basic data reduction steps such as subtraction of dark current, flat fielding, polarization, and wavelength correction were performed using procedures available in SolarSoft (SSW, Bentley & Freeland 1998;Freeland & Handy 1998).…”

Section: Hinode Spectro-polarimetermentioning

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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“…The calibrated data of Stokes profiles (Level 1 data) were generated from Level 0 data by using the Hinode/SOT software package in SolarSoftWare (SSW) system [Freeland and Handy, 1998]. The Level 1 data were employed to check the original data quality of the SP slit scanning measurements, and the calibrated coordinates information of each slit position in the Level 1 data [Centeno et al, 2009] can be helpful for the XRT and EIS images cropping (see section 3.2).…”

Section: Sot-sp Photospheric Vector Magnetogramsmentioning

confidence: 99%

Nonlinear force-free field extrapolation of the coronal magnetic field using the data obtained by the Hinode satellite

Wang

Yan

2011

J. Geophys. Res.

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[1] The Hinode satellite can obtain high-quality photospheric vector magnetograms of solar active regions and the simultaneous coronal loop images in soft X-ray and extreme ultraviolet (EUV) bands. In this paper, we continue the work of and apply the newly developed upward boundary integration computational scheme for the nonlinear force-free field (NLFFF) extrapolation of the coronal magnetic field to the

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Cited by 655 publications

References 2 publications

Transition Region Abundance Measurements During Impulsive Heating Events

Transition Region Abundance Measurements During Impulsive Heating Events

Horizontal flow fields observed in Hinode G-band images

Nonlinear force-free field extrapolation of the coronal magnetic field using the data obtained by the Hinode satellite

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