Allgemeine Kontroversen

Scherrer, Christoph; Lutz-Bachmann, Matthias; Röttger, Bernd

doi:10.1007/978-3-476-05327-5_4

Cited by 6 publications

(5 citation statements)

References 4 publications

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“…For analysis we used the Line-of-Sight (LOS) magnetograms of Active Regions (AR), obtained by the Helioseismic and Magnetic Imager onboard the Solar Dynamics Observatory (SDO/HMI, Scherrer et al 2012). The active region data were represented in the form of 30 o × 30 o data cubes with 1 h cadence, remapped onto the heliographic coordinates using the Postel's projection, and tracked with the solar differential rotation during the whole passage of active regions on the solar disk, employing the standard SDO software.…”

Section: Magnetogram Segmentationmentioning

confidence: 99%

Relationships between Characteristics of the Line-of-sight Magnetic Field and Solar Flare Forecasts

Sadykov

Kosovichev

2017

ApJ

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Section: Magnetogram Segmentationmentioning

confidence: 99%

Relationships between Characteristics of the Line-of-sight Magnetic Field and Solar Flare Forecasts

Sadykov

Kosovichev

2017

ApJ

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“…In order to explore the spatial correlation of multiwavelength emission with photospheric magnetic-field observations, we use observations from Helioseismic Magnetic Imager (HMI; Scherrer et al 2012) onboard the Solar Dynamic Observatory (SDO) mission. It provides full-disk magnetograms at wavelength 6173Å with spatial resolution of 0.5" per pixel and temporal cadence of 45s.…”

Section: Observationsmentioning

confidence: 99%

Multiwavelength diagnostics of the precursor and main phases of an M1.8 flare on 2011 April 22

Awasthi¹,

Jain²,

Gadhiya³

et al. 2013

Monthly Notices of the Royal Astronomical Society

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We study the temporal, spatial and spectral evolution of the M1.8 flare, which occurred in NOAA AR 11195 (S17E31) on 22 April 2011, and explore the underlying physical processes during the precursors and their relation to the main phase. The study of the source morphology using the composite images in 131Å wavelength observed by the SDO/AIA and 6-14 keV revealed a multi-loop system that destabilized systematically during the precursor and main phases. In contrast, HXR emission (20-50 keV) was absent during the precursor phase, appearing only from the onset of the impulsive phase in the form of foot-points of emitting loop/s. This study has also revealed the heated loop-top prior to the loop emission, although no accompanying foot-point sources were observed during the precursor phase. We estimate the flare plasma parameters viz. temperature (T), emission measure (EM), power-law index (γ), and photon turn-over energy ( to ) and found to be varying in the range of 12.4 -23.4 MK, 0.0003 -0.6 × 10 49 cm −3 , 5 to 9 and 14-18 keV, respectively by forward fitting RHESSI spectral observations. The energy released in the precursor phase was thermal and constituted ≈1 per cent of the total energy released during the flare. The study of morphological evolution of the filament in conjunction with synthesized T and EM maps has been carried out which reveals (a) Partial filament eruption prior to the onset of the precursor emission, (b) Heated dense plasma over the polarity inversion line and in the vicinity of the slowly rising filament during the precursor phase. Based on the implications from multi-wavelength observations, we propose a scheme to unify the energy release during the precursor and main phase emissions in which, the precursor phase emission has been originated via conduction front formed due to the partial filament eruption. Next, the heated leftover S-shaped filament has undergone slow rise and heating due to magnetic reconnection and finally erupted to produce emission during the impulsive and gradual phases.

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“…Nowadays, the most common approach to the coronal magnetic field reconstruction is based on a static nonlinear force-free field (NLFFF) model (see reviews by Sakurai 1989;Amari et al 1997;Wiegelmann 2008;Wiegelmann & Sakurai 2012;Wiegelmann et al 2014). NLFFF extrapolations are routinely possible thanks to almost uninterrupted availability of the photospheric full-disk vector magnetic field data starting from the launch of the Solar Dynamics Observatory (SDO, Scherrer et al 2012;Schou et al 2012) in 2010. A more advanced approach based on the dynamic "data-driven" modeling with a number of promising advantages over the static one was also attempted (see, e.g., Jiang et al 2016;Yardley et al 2018) but it is not yet widely used as it requires a lot more resources to reconstruct the field than the NLFFF approach.…”

Section: Introductionmentioning

confidence: 99%

Force-free Field Reconstructions Enhanced by Chromospheric Magnetic Field Data

Fleishman

Myshyakov

Stupishin

et al. 2019

ApJ

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3D picture of the coronal magnetic field remains an outstanding problem in solar physics, particularly, in active regions. Nonlinear force-free field reconstructions that employ routinely available full-disk photospheric vector magnetograms represent state-of-the-art coronal magnetic field modeling. Such reconstructions, however, suffer from an inconsistency between a force-free coronal magnetic field and non-force-free photospheric boundary condition, from which the coronal reconstruction is performed. In this study we focus on integrating the additional chromospheric and / or coronal magnetic field data with the vector photospheric magnetograms with the goal of improving the reliability of the magnetic field reconstructions. We develop a corresponding modification of the available optimization codes described in Fleishman et al. (2017) and test their performance using a full-fledged MHD model obtained from the Bifrost code by performing a "voxel-by-voxel" comparison between the reconstructed and the model magnetic fields. We demonstrate that adding even an incomplete set of chromospheric magnetic field data can measurably improve the reconstruction of the coronal magnetic field, greatly improve reconstructions of the magnetic connectivity and of the coronal electric current.

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Allgemeine Kontroversen

Cited by 6 publications

References 4 publications

Relationships between Characteristics of the Line-of-sight Magnetic Field and Solar Flare Forecasts

Relationships between Characteristics of the Line-of-sight Magnetic Field and Solar Flare Forecasts

Multiwavelength diagnostics of the precursor and main phases of an M1.8 flare on 2011 April 22

Force-free Field Reconstructions Enhanced by Chromospheric Magnetic Field Data

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