The proton flare of August 28, 1966

Dodson, Helen W.; Hedeman, E. Ruth

doi:10.1007/bf00148084

Cited by 36 publications

(18 citation statements)

References 5 publications

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“…The plasma is pushed down, but due to inertia it takes some time to get maximum compression. In this period of downward plasma motion the Moreton wave is seen in absorption in the red wing of the Hα line and in emission in the blue wing (Dodson & Hedeman 1968). In the line center, the maximum ∆I in Hα is reached (r = 3 in Fig.…”

Section: The Main Perturbation Dipmentioning

confidence: 89%

Flare waves observed in Helium I 10 830 Å

Vršnak¹,

Warmuth²,

Brajša³

et al. 2002

A&A

118

115

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Abstract. Three traveling disturbances recorded in the absorption line of Helium I at 10 830 Å (He I), analogous to Hα Moreton waves, are analyzed. The morphology and kinematics of the wavefronts are described in detail. The He I wave appears as an expanding arc of increased absorption roughly corresponding to the Hα disturbance, although not as sharply defined. He I perturbations consist of a relatively uniform diffuse component and a patchy one that appears as enhanced absorption in He I mottles. It leads the Hα front by some 20 Mm and can be followed to considerably larger distances than in Hα observations. Behind the front stationary areas of reduced He I absorption develop, resembling EUV coronal dimming. The observed He I as well as the Hα disturbances show a deceleration of the order of 100-1000 m s −2 . Moreover, in the event where Hα, He I, and EUV wavefronts are observed, all of them follow closely related kinematical curves, indicating that they are a consequence of a common disturbance. The analysis of spatial perturbation profiles indicates that He I disturbances consist of a forerunner and a main dip, the latter being cospatial with the Hα disturbance. The properties and behavior of the wavefronts can be comprehended as a consequence of a fast-mode MHD coronal shock whose front is weakly inclined to the solar surface. The Hα disturbance and the main He I dip are a consequence of the pressure jump in the corona behind the shock front. The He I forerunner might be caused by thermal conduction from the oblique shock segments ahead of the shock-chromosphere intersection, or by electron beams accelerated in the quasi-perpendicular section of the shock.

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Section: The Main Perturbation Dipmentioning

confidence: 89%

Flare waves observed in Helium I 10 830 Å

Vršnak¹,

Warmuth²,

Brajša³

et al. 2002

A&A

118

115

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“…The downward and upward oscillation of the chromosphere damps out after only one to two oscillations. Similar sudden vertical oscillations in filaments (Dodson & Hedeman 1964;Ramsey & Smith 1966) had been first seen in H line-center images as ''winking '' filaments that momentarily flickered out and back into view, always within minutes of an exceptionally bright flare in a neighboring region (Dodson 1949;Bruzek 1951; see references in Smith & Harvey 1971). The measured speed of the visible chromospheric waves were initially found to be in the range 500-2000 km s À1 , and the propagating front was thought to be confined within a $90 sector angle (Moreton 1960;Athay & Moreton 1961).…”

Section: Introductionmentioning

confidence: 88%

“…The classic chromospheric flare wave, also known as a Moreton wave (Moreton 1960;Athay & Moreton 1961;Dodson & Hedeman 1964;Dodson & Hedeman 1968;Smith & Harvey 1971), appears in images in the wings of H as both bright and dark parallel fronts propagating in an arc, away from the site of solar flare. The bright /dark front (or dark / bright in the opposite wing of H) is due to the successive depression and relaxation of chromospheric structures caused by the pressure of an overlying coronal wave assumed to propagate at high velocity through the corona from the site of a solar flare.…”

Section: Introductionmentioning

confidence: 99%

Sequential Chromospheric Brightenings beneath a Transequatorial Halo Coronal Mass Ejection

Balasubramaniam

Pevtsov

Neidig

et al. 2005

ApJ

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Analyses of multiwavelength data sets for a solar eruption at $21:30 UT on 2002 December 19 show evidence for the disappearance of a large-scale, transequatorial coronal loop ( TL). In addition, coronal manifestations of the eruption ( based on SOHO EIT and LASCO images) include large-scale coronal dimming, flares in each associated active region in the northern and southern hemispheres, and a halo CME. We present detailed observations of the chromospheric aspects of this event based on H images obtained with the ISOON telescope. The ISOON images reveal distant flare precursor brightenings, sympathetic flares, and, of most interest herein, four nearly cospatial propagating chromospheric brightenings. The speeds of the propagating disturbances causing these brightenings are 600-800 km s À1 . The inferred propagating disturbances have some of the characteristics of H and EIT flare waves (e.g., speed, apparent emanation from the flare site, subsequent filament activation). However, they differ from typical H chromospheric flare waves (also known as Moreton waves) because of their absence in off-band H images, small angular arc of propagation (<30 ), and their multiplicity. Three of the four propagating disturbances consist of a series of sequential chromospheric brightenings of network points that suddenly brighten in the area beneath the TL that disappeared earlier. SOHO MDI magnetograms show that the successively brightened points that define the inferred propagating disturbances were exclusively of one polarity, corresponding to the dominant polarity of the affected region. We speculate that the sequential chromospheric brightenings represent footpoints of field lines that extend into the corona, where they are energized in sequence by magnetic reconnection as coronal fields tear away from the chromosphere during the eruption of the transequatorial CME. We report briefly on three other events with similar narrow propagating disturbances that were confined to a single hemisphere.

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“…Moreton waves, large-scale waves observed in Hα emanating from the sites of major solar flares, were first reported 50 years ago (Moreton 1960(Moreton , 1961(Moreton , 1964Moreton & Ramsey 1960;Athay & Moreton 1961;Dodson & Hedeman 1964;Ramsey & Smith 1966;Dodson & Hedeman 1968). Such waves have characteristic speeds of ∼1000 km s −1 and tend to be directional, with angular widths typically in the range from 60 • to 150 • (Smith & Harvey 1971;Warmuth et al 2004a;Veronig et al 2006), although cases with fragmented arcs collectively spanning larger angles have been reported (Pick et al 2005;Balasubramaniam et al 2007;Muhr et al 2008Muhr et al , 2010.…”

Section: Introductionmentioning

confidence: 99%

On the Origin of the Solar Moreton Wave of 2006 December 6

Balasubramaniam

Cliver

Pevtsov

et al. 2010

ApJ

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We analyzed ground-and space-based observations of the eruptive flare (3B/X6.5) and associated Moreton wave (∼850 km s −1 ; ∼270 • azimuthal span) of 2006 December 6 to determine the wave driver-either flare pressure pulse (blast) or coronal mass ejection (CME). Kinematic analysis favors a CME driver of the wave, despite key gaps in coronal data. The CME scenario has a less constrained/smoother velocity versus time profile than is the case for the flare hypothesis and requires an acceleration rate more in accord with observations. The CME picture is based, in part, on the assumption that a strong and impulsive magnetic field change observed by a GONG magnetograph during the rapid rise phase of the flare corresponds to the main acceleration phase of the CME. The Moreton wave evolution tracks the inferred eruption of an extended coronal arcade, overlying a region of weak magnetic field to the west of the principal flare in NOAA active region 10930. Observations of Hα foot point brightenings, disturbance contours in off-band Hα images, and He i 10830 Å flare ribbons trace the eruption from 18:42 to 18:44 UT as it progressed southwest along the arcade. Hinode EIS observations show strong blueshifts at foot points of this arcade during the post-eruption phase, indicating mass outflow. At 18:45 UT, the Moreton wave exhibited two separate arcs (one off each flank of the tip of the arcade) that merged and coalesced by 18:47 UT to form a single smooth wave front, having its maximum amplitude in the southwest direction. We suggest that the erupting arcade (i.e., CME) expanded laterally to drive a coronal shock responsible for the Moreton wave. We attribute a darkening in Hα from a region underlying the arcade to absorption by faint unresolved post-eruption loops.

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The proton flare of August 28, 1966

Cited by 36 publications

References 5 publications

Flare waves observed in Helium I 10 830 Å

Flare waves observed in Helium I 10 830 Å

Sequential Chromospheric Brightenings beneath a Transequatorial Halo Coronal Mass Ejection

On the Origin of the Solar Moreton Wave of 2006 December 6

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