Study of the post-flare loops on 29 July 1973

Švestka, Z.; Dodson-Prince, H. W.; Martin, Sara; Mohler, Orren C.; Moore, Ronald L.; Nolte, J. T.; Petrasso, R. D.

doi:10.1007/bf00151609

Cited by 47 publications

(22 citation statements)

References 14 publications

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“…Prior to these observations, the duration of reconnection processes was usually inferred from either the time over which chromospheric ribbons kept separating or the time over which hot loops kept rising to higher altitudes. From the time history of the H ribbon separation and of the hot loop heights for the 1973 July 29 flare that was considered to be an ideal example for a case study (see, e.g., Moore et al 1980;Svestka et al 1982), reconnection was recognized to go on for at least %10 hr. Hence, UVCS data considerably extended the time interval over which reconnection was observed to operate.…”

Section: Discussionmentioning

confidence: 99%

Current Sheet Evolution in the Aftermath of a CME Event

Бемпорад

Poletto

Suess

et al. 2006

ApJ

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We report on SOHO UVCS observations of the coronal restructuring following a coronal mass ejection (CME) on 2002 November 26, at the time of a SOHO-Ulysses quadrature campaign. Starting about 1.5 hr after a CME in the northwest quadrant, UVCS began taking spectra at 1.7 R , covering emission from both cool and hot plasma. Observations continued, with occasional gaps, for more than 2 days. Emission in the 974.8 8 line of [Fe xviii], indicating temperatures above 6 ; 10 6 K, was observed throughout the campaign in a spatially limited location. Comparison with EIT images shows the [Fe xviii] emission to overlie a growing post-flare loop system formed in the aftermath of the CME. The emission most likely originates in a current sheet overlying the arcade. Analysis of the [Fe xviii] emission allows us to infer the evolution of physical parameters in the current sheet over the entire span of our observations: in particular, we give the temperature versus time in the current sheet and estimate its density. At the time of the quadrature, Ulysses was directly above the location of the CME and intercepted the ejecta. High ionization state Fe was detected by the Ulysses SWICS throughout the magnetic cloud associated with the CME, although its rapid temporal variation suggests bursty, rather than smooth, reconnection in the coronal current sheet. The SOHOUlysses data set provided us with the unique opportunity of analyzing a current sheet structure from its lowest coronal levels out to its in situ properties. Both the remote and in situ observations are compared with predictions of theoretical CME models.

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Section: Discussionmentioning

confidence: 99%

Current Sheet Evolution in the Aftermath of a CME Event

Бемпорад

Poletto

Suess

et al. 2006

ApJ

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“…In addition to the above-mentioned data, the 29 July, 1973 flare comprises an ideal example for a case study because our knowledge of the plasma physical conditions at the tops of the flare loops now appears to be fairly reliable (Svestka et aL, 1982). The latitude and size of this flare suggest that the eighth lobe of a Pls-field is appropriate.…”

Section: The 29 July 1973 Flarementioning

confidence: 96%

Extension of the reconnection theory of two-ribbon solar flares

Kopp

Poletto

1984

Sol Phys

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Abstract. The magnetic reconnection theory for two-ribbon flares and flare loops hypothesizes that the gradual energy release during the decay phase is a direct result of dissipative relaxation of the open coronal magnetic configuration created by an eruptive prominence/coronal transient precursor. This scenario is here developed quantitatively to the point where a realistic comparison with observational data can be attempted. Our major refinements are (i) to use an analytical description of the reconnecting field geometry specifically chosen to characterize the spatial scale of the active region where a flare occurs, and (ii) to take account of the fact that the volume occupied by X-ray-emitting plasma (hot loops) generally increases with time during the flare.As a test of the modified theory we have undertaken a new representation of the Skylab observations of the large two-ribbon flare of 29 July, 1973, It is hereby found that the simultaneous inclusion of the above two factors yields an excellent agreement between the theoretical prediction and observations of the time variation of flare-plasma energy density; such was not possible within the framework of previous work along these lines. The agreement extends, moreover, to rather early times in the flare history, where the shortcomings of earlier studies became especially noticeable. This result constitutes strong evidence to support previous speculations that magnetic reconnection may provide the sole energy source throughout nearly the entire flare lifetime.

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“…Moreover, it was found that the cooling time can be estimated by using the velocity and the width of the flare ribbons (Švestka et al 1982;Priest & Forbes 2002). The PFLs are observed expanding in a particular wavelength during the 8 cooling process.…”

Section: Cooling Process Of Dpflsmentioning

confidence: 99%

Dark Post-Flare Loops Observed by the Solar Dynamics Observatory

Song

Wang

Feng

et al. 2016

ApJ

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Solar post-flare loops (PFLs) are arcade-like loop systems that appear during the gradual phases of eruptive flares. The extreme ultraviolet (EUV) observations from the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO) allow us to investigate the fine structures in PFLs. In this work, we focus on studying the dark post-flare loops (DPFLs) during X-class flares, which are more evident in SDO/AIA data than in previous EUV data. We identify and analyze the DPFLs observed by SDO and find that: , and (3) the average widths of the DPFLs slightly increase with the characteristic temperatures in the AIA 304, 171, 193, and 211 Å channels. Our investigation shows that DPFLs are found in all of the 20 cases within this study, which suggests that they are a common phenomenon in X-class flares and are probably produced by the same mechanism that creates coronal rain.

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Study of the post-flare loops on 29 July 1973

Cited by 47 publications

References 14 publications

Current Sheet Evolution in the Aftermath of a CME Event

Current Sheet Evolution in the Aftermath of a CME Event

Extension of the reconnection theory of two-ribbon solar flares

Dark Post-Flare Loops Observed by the Solar Dynamics Observatory

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