The explosive phase of solar flares

Harvey, K. L.

doi:10.1007/bf00162485

Cited by 16 publications

(4 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The Hα RD images in Figure 7 (scaled to enhance the frame-to-frame changes) show that a significant expansion of flare area occurred from 18:42 to 18:43 UT. Following the definition of Harvey (1971), this interval is the flare "explosive phase," the minute during which the integrated flare intensity first increases by >25% of the peak intensity (Figure 8(a)). Smith & Harvey (1971) showed that the show that the impulsive heating in this event began no earlier than 18:42 UT.…”

Section: Event Overviewmentioning

confidence: 99%

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

Balasubramaniam

Cliver

Pevtsov

et al. 2010

ApJ

View full text Add to dashboard Cite

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.

show abstract

Section: Event Overviewmentioning

confidence: 99%

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

Balasubramaniam

Cliver

Pevtsov

et al. 2010

ApJ

View full text Add to dashboard Cite

show abstract

“…Following the early work of Covington and Harvey (1961b), the explosive phase and its relationship with the impulsive X-ray, EUV and microwave emission has been studied by Moreton (1964), Davies and Don nelly (1966), Angle (1968), and Harvey (1971). The observed good correlation clearly indicates that the explosive phase is nearly coincident with the impulsive phase de fined here.…”

Section: 'Monochromatic'observationsmentioning

confidence: 62%

“…It has been known for some time that the impulsive phase may occur only in a small part of an Ha-flare (Dodson et al 9 1956;Dodson and Hedeman, 1968;Har vey, 1971;Vorpahl, 1972). An example of the development of a large flare (Haimportance ^3) is shown in Figure 18 (Harvey, 1971) broad band measurements reported in the literature are those made by Zirin (1972) in the 15 A band centered at 3835 A. They did not find any increase in the emission of 3835 A even in fairly large flares indicating that in most flares there is no significant heating of the lower chromosphere at a height where the density is ~ 10 17 particles cm" 3 .…”

Section: 'Monochromatic'observationsmentioning

confidence: 99%

Impulsive (Flash) Phase of Solar Flares: Hard X-Ray, Microwave, EUV and Optical Observations

Kane

1974

Symp. - Int. Astron. Union

View full text Add to dashboard Cite

Abstract. Recent observations of impulsive hard X-ray, microwave, EUV and optical emissions during solar flares are briefly reviewed in order to deduce the characteristics of the impulsive (flash) phase phenomenon in small solar flares particularly from the point of view of the acceleration of electrons and their role in producing the various impulsive phase emissions. Observed and deduced characteristics of the various electromagnetic emission sources are summarized (Table II). The deduced characteristics of the electron acceleration process (Table III) indicate a process with high acceleration efficiency. The ob servations are found to be consistent with a model in which electrons are accelerated in a series of short pulses each lasting for ^ 1 s and the accelerated electrons provide the energy necessary for all the observed electromagnetic emissions produced during the flash phase of small solar flares. Models of the impulsive phase emissions in which energetic electrons play a prominant role are examined and crucial tests to check the accuracy of these models are indicated (Table IV).

show abstract

“…When a solar flare occurs, the Sun will burst a large amount of energy with various radiation and energetic charged particles [23]. Based on the soft X-ray intensity in the wavelength range of 1 to 8 Å, flares can be divided into A, B, C, M and X categories [24].…”

Section: The Correlation Between Martian Ionosphere and Solar Flaresmentioning

confidence: 99%

An Investigation on the Distribution of Martian Ionospheric Particles, Based on the Mars Atmosphere and Volatile Evolution (MAVEN)

Qiu,

Li,

Soon

2024

Universe

View full text Add to dashboard Cite

In this paper, we use the key parameters data set of the Neutral Gas and Ion Mass Spectrometer from the Mars Atmosphere and Volatile Evolution (MAVEN) mission. The particle density profiles of electrons, CO2+/N2+, CO+, O2+, O+, NO+, O2 and O from 90 to 500 km have been deduced by adopting the Chapman modeling methodology. The correlation of the peak density/altitude with the solar zenith angle, the changes in the profile of the Martian ionosphere during solar flares, and the effects of Martian dust storms are analyzed. The results exhibit a positive/negative correlation between the peak density/altitude of the M2 layer and the solar zenith angle. Within the MAVEN observational record available, only three C-Class flares occurred on 26 August 2016, 29 November 2020, and 26 August 2021. The analysis reveals during these solar flare events, the electron density of the M2 layer above 200 km increases obviously. The peak density of M1 increases by 33.4%, 13.2% and 7.4%, while the peak height decreases by 0.1%, 10.2% and 4.4%, respectively. The Martian dust storm causes the peak height of the M2 layer to increase by 19.5 km, and the peak density to decrease by 4.2 × 109 m−3. Our study shows that the Martian ionosphere is similar to the Earth’s, which is of great significance for understanding the planetary ionosphere.

show abstract

The explosive phase of solar flares

Cited by 16 publications

References 11 publications

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

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

Impulsive (Flash) Phase of Solar Flares: Hard X-Ray, Microwave, EUV and Optical Observations

An Investigation on the Distribution of Martian Ionospheric Particles, Based on the Mars Atmosphere and Volatile Evolution (MAVEN)

Contact Info

Product

Resources

About