Hα Observations of Flare-Initiated Disturbances with Velocities ~1000 km/sec.

Moreton, G. E.

doi:10.1086/108346

Cited by 229 publications

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“…In the 1960s, the expected disturbances were directly imaged in Hα (Moreton, 1960;Moreton and Ramsey, 1960;Athay and Moreton, 1961), where they are seen as arc-shaped bright fronts. These Moreton waves were interpreted as the chromospheric ground track of an expanding coronal wavefront (Uchida, 1968).…”

Section: Overviewmentioning

confidence: 99%

“…These Moreton waves (Moreton, 1960;Moreton and Ramsey, 1960;Athay and Moreton, 1961) appear as arc-shaped fronts propagating away from flaring active regions at speeds of the order of 1000 km s -1 (see Figure 9 and the animation in Figure 10 for an example). The fronts are seen as emission enhancements in the center and in the blue wing of the Hα line (i.e., bright fronts), whereas in the red wing they appear as emission depletions (dark fronts).…”

Section: Hα (Moreton Waves)mentioning

confidence: 99%

“…It has been known for a long time that Moreton waves can cause filament oscillations (Moreton, 1960(Moreton, , 1964Ramsey and Smith, 1966;Liu et al, 2013), which are usually observed as "winking filaments". If the line-of sight component of the oscillation exceeds 20 km s -1 , the filament vanishes from and subsequently reappears in Hα line center filtergrams (for a review of filament oscillations, see Arregui et al, 2012).…”

Section: Excitation Of Oscillationsmentioning

confidence: 99%

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Large-scale Globally Propagating Coronal Waves

Warmuth

2015

Living Rev. Sol. Phys.

163

140

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Large-scale, globally propagating wave-like disturbances have been observed in the solar chromosphere and by inference in the corona since the 1960s. However, detailed analysis of these phenomena has only been conducted since the late 1990s. This was prompted by the availability of high-cadence coronal imaging data from numerous spaced-based instruments, which routinely show spectacular globally propagating bright fronts. Coronal waves, as these perturbations are usually referred to, have now been observed in a wide range of spectral channels, yielding a wealth of information. Many findings have supported the "classical" interpretation of the disturbances: fast-mode MHD waves or shocks that are propagating in the solar corona. However, observations that seemed inconsistent with this picture have stimulated the development of alternative models in which "pseudo waves" are generated by magnetic reconfiguration in the framework of an expanding coronal mass ejection. This has resulted in a vigorous debate on the physical nature of these disturbances. This review focuses on demonstrating how the numerous observational findings of the last one and a half decades can be used to constrain our models of large-scale coronal waves, and how a coherent physical understanding of these disturbances is finally emerging. Article RevisionsLiving Reviews supports two ways of keeping its articles up-to-date:Fast-track revision. A fast-track revision provides the author with the opportunity to add short notices of current research results, trends and developments, or important publications to the article. A fast-track revision is refereed by the responsible subject editor. If an article has undergone a fast-track revision, a summary of changes will be listed here.Major update. A major update will include substantial changes and additions and is subject to full external refereeing. It is published with a new publication number.For detailed documentation of an article's evolution, please refer to the history document of the article's online version at http://dx

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Section: Overviewmentioning

confidence: 99%

Section: Hα (Moreton Waves)mentioning

confidence: 99%

Section: Excitation Of Oscillationsmentioning

confidence: 99%

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Large-scale Globally Propagating Coronal Waves

Warmuth

2015

Living Rev. Sol. Phys.

163

140

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“…Type II radio bursts have long been observed in the solar corona associated with solar eruptions (e.g. Payne-Scott, Yabsley, and Bolton, 1947;Wild and McCready, 1950) and it was generally accepted that both type II bursts and Moreton-Ramsey waves (first observed in the 1960s by Moreton, 1960;Moreton and Ramsey, 1960) were signatures of the same driving process (Uchida, 1968). However, the much lower measured speeds and other discrepancies between Moreton-Ramsey and global EIT waves complicated extending this assumption to EIT waves.…”

Section: Introductionmentioning

confidence: 99%

A Statistical Analysis of the Solar Phenomena Associated with Global EUV Waves

et al. 2017

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Solar eruptions are the most spectacular events in our solar system and are associated with many different signatures of energy release including solar flares, coronal mass ejections, global waves, radio emission and accelerated particles. Here, we apply the Coronal Pulse Identification and Tracking Algorithm (CorPITA) to the high-cadence synoptic data provided by the Solar Dynamics Observatory (SDO) to identify and track global waves observed by SDO. 164 of the 362 solar flare events studied (45%) were found to have associated global waves with no waves found for the remaining 198 (55%). A clear linear relationship was found between the median initial velocity and the acceleration of the waves, with faster waves exhibiting a stronger deceleration (consistent with previous results). No clear relationship was found between global waves and type II radio bursts, electrons or protons detected in situ near Earth. While no relationship was found between the wave properties and the associated flare size (with waves produced by flares from B to X-class), more than a quarter of the active regions studied were found to produce more than one wave event. These results suggest that the presence of a global wave in a solar eruption is most likely determined by the structure and connectivity of the erupting active region and the surrounding quiet solar corona rather than by the amount of free energy available within the active region.

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“…Uchida's magnetohydrodynamic (MHD) model interpreted the disturbances observed in Hα, which were discovered by Moreton (1960), Moreton and Ramsey (1960), and Athay and Moreton (1961). These so-called Moreton waves were observed in association with the most impulsive flares as arc-shaped fronts with a restricted angular span propagating with speeds of 500 -1500 km s −1 to distances of up to 400 Mm.…”

Section: Introductionmentioning

confidence: 99%

Moreton and EUV Waves Associated with an X1.0 Flare and CME Ejection

et al. 2016

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Several other phenomena took place in connection with this event, such as low coronal waves and a coronal mass ejection (CME). We analyze the association between the Moreton wave and the EUV signatures observed with the Atmospheric Imaging Assembly onboard the Solar Dynamics Observatory. These include their low-coronal surface-imprint, and the signatures of the full wave and shock dome propagating outward in the corona. We also study their relation to the whitelight CME. We perform a kinematic analysis by tracking the wavefronts in several directions. This analysis reveals a high-directional dependence of accelerations and speeds determined from data at various wavelengths. We speculate that a region of open magnetic field lines northward of our defined radiant point sets favorable conditions for the propagation of a coronal magnetohydrodynamic shock in this direction. The hypothesis that the Moreton wavefront is produced by a coronal shock-wave that pushes the chromosphere downward is supported by the high compression ratio in that region. Furthermore, we propose a 3D geometrical model to explain the observed wavefronts as the chromospheric and low-coronal traces of an expanding and outward-traveling bubble intersecting the Sun. The results of the model are in agreement with the coronal shock-wave being generated by a 3D piston that expands at the speed of the associated rising filament. The piston is attributed to the fast ejection of the filament -CME ensemble, also consistent with the good match between the speed profiles of the low-coronal and white-light shock-waves.

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Hα Observations of Flare-Initiated Disturbances with Velocities ~1000 km/sec.

Cited by 229 publications

References 0 publications

Large-scale Globally Propagating Coronal Waves

Large-scale Globally Propagating Coronal Waves

A Statistical Analysis of the Solar Phenomena Associated with Global EUV Waves

Moreton and EUV Waves Associated with an X1.0 Flare and CME Ejection

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