Seismic Images of a Solar Flare

Donea, Alina-Catalina; Braun, D. C.; Lindsey, C.

doi:10.1086/311915

Cited by 94 publications

(114 citation statements)

References 19 publications

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“…The radiant points of the waves closely match the various signatures of the impulsive phase (Fig. 14;Lindsey and Donea 2008), and the optimum frequency bands for the holographic technique (Lindsey and Braun 1990;Donea et al 1999) appear to be 3-7 mHz, corresponding to time scales (2πω) −1 of 10-50 s.…”

Section: Seismic Wavesmentioning

confidence: 54%

Global Properties of Solar Flares

2011

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This article broadly reviews our knowledge of solar flares. There is a particular focus on their global properties, as opposed to the microphysics such as that needed for magnetic reconnection or particle acceleration as such. Indeed solar flares will always remain in the domain of remote sensing, so we cannot observe the microscales directly and must understand the basic physics entirely via the global properties plus theoretical inference. The global observables include the general energetics-radiation in flares and mass loss in coronal mass ejections (CMEs)-and the formation of different kinds of ejection and global wave disturbance: the type II radio-burst exciter, the Moreton wave, the EIT "wave", and the "sunquake" acoustic waves in the solar interior. Flare radiation and CME kinetic energy can have comparable magnitudes, of order 10 32 erg each for an X-class event, with the bulk of the radiant energy in the visible-UV continuum. We argue that the impulsive phase of the flare dominates the energetics of all of these manifestations, and also point out that energy and momentum in this phase largely reside in the electromagnetic field, not in the observable plasma.

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Section: Seismic Wavesmentioning

confidence: 54%

Global Properties of Solar Flares

2011

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“…At this depth, a field strength of ≈ 80 kG is inferred from flux-tube emerging calculations (see e.g. D'Silva and Choudhuri, 1993;Caligari, Moreno-Insertis, and Schüssler, 1995). The Alfvén travel time for a change at the base to propagate to the surface (more accurately: the propagation time of a transverse tube wave) is then about five days.…”

Section: The Anchoring Problemmentioning

confidence: 93%

“…Quite clear, however, is the picture of flux emergence: the process by which a loop of flux rises from a horizontal layer of magnetic flux at the base of the convection zone to form an active region, as discussed briefly in Section 2.1.1. Simplified 1D calculations in the "thin tube" approximation (D'Silva and Choudhuri, 1993;Fan, Fisher, and McClymont, 1994;Caligari, Moreno-Insertis, and Schüssler, 1995) point to a field strength of about 10 5 G at the base of the convection zone. At this strength, agreement is reached with three independent key properties of active regions: i) the time scale of emergence (a few days), ii) the heliographic-latitude range of emergence, and iii) the tilt of active-region axes (e.g.…”

Section: The Issue Of Flux Emergencementioning

confidence: 97%

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Modeling the Subsurface Structure of Sunspots

et al. 2010

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While sunspots are easily observed at the solar surface, determining their subsurface structure is not trivial. There are two main hypotheses for the subsurface structure of sunspots: the monolithic model and the cluster model. Local helioseismology is the only means by which we can investigate subphotospheric structure. However, as current linear inversion techniques do not yet allow helioseismology to probe the internal structure with sufficient confidence to distinguish between the monolith and cluster models, the development of physically realistic sunspot models are a priority for helioseismologists. This is because they are not only important indicators of the variety of physical effects that may influence helioseismic inferences in active regions, but they also enable detailed assessments of the validity of helioseismic interpretations through numerical forward modeling. In this article, we provide a critical review of the existing sunspot models and an overview of numerical methods employed to model wave propagation through model sunspots. We then carry out a helioseismic analysis of the sunspot in Active Region 9787 and address the serious inconsistencies uncovered by Gizon et al. (2009aGizon et al. ( , 2009b. We find that this sunspot is most probably associated with a shallow, positive wave-speed perturbation (unlike the traditional two-layer model) and that travel-time measurements are consistent with a horizontal outflow in the surrounding moat.

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“…13a), [90][91][92][93], or indirectly by calculating integrated acoustic emission [94][95][96]. Solar flares are sources of high-temperature plasma and strong hydrodynamic motions in the solar atmosphere.…”

Section: Magnetic Effects: Sunspot Oscillations and Acoustic Halosmentioning

confidence: 99%

Advances in Global and Local Helioseismology: An Introductory Review

Kosovichev

2011

The Pulsations of the Sun and the Stars

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Abstract. Helioseismology studies the structure and dynamics of the Sun's interior by observing oscillations on the surface. These studies provide information about the physical processes that control the evolution and magnetic activity of the Sun. In recent years, helioseismology has made substantial progress towards the understanding of the physics of solar oscillations and the physical processes inside the Sun, thanks to observational, theoretical and modeling efforts. In addition to the global seismology of the Sun based on measurements of global oscillation modes, a new field of local helioseismology, which studies oscillation travel times and local frequency shifts, has been developed. It is capable of providing 3D images of the subsurface structures and flows. The basic principles, recent advances and perspectives of global and local helioseismology are reviewed in this article.

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Seismic Images of a Solar Flare

Cited by 94 publications

References 19 publications

Global Properties of Solar Flares

Global Properties of Solar Flares

Modeling the Subsurface Structure of Sunspots

Advances in Global and Local Helioseismology: An Introductory Review

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