Dark Post-Flare Loops Observed by the Solar Dynamics Observatory

Song, Qiao; Wang, Jingsong; Feng, Xueshang; Zhang, Xiao‐Xin

doi:10.3847/0004-637x/821/2/83

Cited by 14 publications

(12 citation statements)

References 111 publications

(166 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The sudden darkening of the bright EUV loop in our simulation resembles the dark postflare loop (DPFL) phenomenon, previously observed at the same 17.1 nm passband and with similar timescale of 10 minutes [32]. Observed DPFLs and the disappearing EUV coronal loop in our simulation also share the same time evolution of integral EUV flux: the EUV flux reaches its minimum value when the darkening happens (compare Fig.…”

Section: Coronal Rain and Dark Post-flare Loopssupporting

confidence: 85%

“…Another phenomenon thought to have a close relationship with these sudden condensations are the so-called dark post-flare loops (DPFLs), where some PFL loops suddenly vanish from specific EUV passbands, e.g. at 17.1 nm, 30.4 nm and 21.1 nm [32,33,34]. In these DPFLs, an EUV loop which was bright for a while suddenly darkens for several minutes, so effectively disappears between the adjacent EUV loops seen at the same height.…”

mentioning

confidence: 99%

See 1 more Smart Citation

When hot meets cold: post-flare coronal rain

Ruan

Zhou

Keppens

2021

Preprint

View full text Add to dashboard Cite

All solar flares demonstrate a prolonged, hourlong post-flare (or gradual) phase, characterized by arcade-like, post-flare loops (PFLs) visible in many extreme ultraviolet (EUV) passbands. These coronal loops are filled with hot – ~30MK – and dense plasma, evaporated from the chromosphere during the impulsive phase of the flare, and they very gradually recover to normal coronal density and temperature conditions. During this gradual cooling down to ~1MK regimes, much cooler – ~0.01MK – and denser coronal rain is frequently observed inside PFLs. Understanding PFL dynamics in this long-duration, gradual phase is crucial to the entire corona-chromosphere mass and energy cycle. Here we report the first simulation in which a solar flare evolves from pre-flare, over impulsive phase all the way into its gradual phase, which successfully reproduces post-flare coronal rain. This rain results from catastrophic cooling caused by thermal instability, and we analyse the entire mass and energy budget evolution driving this sudden condensation phenomenon. We find that the runaway cooling and rain formation also induces the appearance of dark post-flare loop systems, as observed in EUV channels. We confirm and augment earlier observational findings, suggesting that thermal conduction and radiative losses alternately dominate the cooling of PFLs. Since reconnection-driven flares occur in many astrophysical settings (stellar flares, accretion disks, galactic winds and jets), our study suggests a new and natural pathway to introduce multi-thermal structuring.

show abstract

Section: Coronal Rain and Dark Post-flare Loopssupporting

confidence: 85%

mentioning

confidence: 99%

When hot meets cold: post-flare coronal rain

Ruan

Zhou

Keppens

2021

Preprint

View full text Add to dashboard Cite

show abstract

“…These authors have highlighted multi-stranded and multi-thermal structure, but without reference to broad line widths. Plasma condensation after eruptive flares can produce similar phenomena (Song et al 2016), although the physical processes may differ. Kleint et al (2014) have found bursty flows associated with brightpoints at the edge of the sunspot umbra, that show a striking similarity to the profiles analyzed here, but lasting only ∼20 s.…”

Section: Introductionmentioning

confidence: 99%

An Explanation of Remarkable Emission-line Profiles in Post-flare Coronal Rain

Lacatus¹,

Judge

Donea³

2017

ApJ

View full text Add to dashboard Cite

We study broad red-shifted emission in chromospheric and transition region lines that appears to correspond to a form of post-flare coronal rain. Profiles of Mg II, C II and Si IV lines were obtained using the IRIS instrument before, during and after the X2.1 flare of 11 March 2015. We analyze the profiles of the five transitions of Mg II (the 3p − 3s h and k transitions, and three lines belonging to the 3d − 3p transitions). We use analytical methods to understand the unusual profiles, together with higher resolution observational data of similar phenomena observed by Jing et al. (2016). The peculiar line ratios indicate anisotropic emission from the strands which have cross-strand line center optical depths (k-line) of between 1 and 10. The lines are broadened by unresolved Alfvénic motions whose energy exceeds the radiation losses in the Mg II lines by an order of magnitude. The decay of the line widths is accompanied by a decay in the brightness, suggesting a causal connection. If the plasma is ∼ < 99% ionized, ion-neutral collisions can account for the dissipation, otherwise a of dynamical process seems necessary. Our work implies that the motions are initiated during the impulsive phase, to be dissipated as radiation over a period of an hour, predominantly by strong chromospheric lines. The coronal "rain" we observe is far more turbulent that most earlier reports have indicated, with implications for plasma heating mechanisms.

show abstract

“…The different observations in these different wavebands may indicate that this long line structure has a high temperature and it may be a current sheet produced by the magnetic reconnection of the eruption. The eruption was without significant X-ray enhancement, but had growing post-eruption arcades which are similar to the post-flare loops (Song et al 2016) and can be explained by the standard flare model. A CME can be observed from the image of SOHO/LASCO and it may cause disturbance to the interplanetary space.…”

Section: Resultsmentioning

confidence: 67%

On the Role of Magnetic Fields in an Erupting Solar Filament

2019

Self Cite

View full text Add to dashboard Cite

A filament eruption may lead to a coronal mass ejection (CME), which is one of the main driving mechanisms of space weather. This work analyses a slow and flareless CME event associated with an erupting quiescent filament. By using the extreme ultraviolet images of the Atmospheric Imaging Assembly onboard the Solar Dynamics Observatory, we trace the evolution of the filament in detail, and present the manifestations of the role of magnetic fields in the low corona. The results suggest the existence of a magnetic flux rope in the pre-eruption structures. Our study of this complex magnetic system may lead to a better understanding of CMEs and their impact on the space weather.

show abstract

Dark Post-Flare Loops Observed by the Solar Dynamics Observatory

Cited by 14 publications

References 111 publications

When hot meets cold: post-flare coronal rain

When hot meets cold: post-flare coronal rain

An Explanation of Remarkable Emission-line Profiles in Post-flare Coronal Rain

On the Role of Magnetic Fields in an Erupting Solar Filament

Contact Info

Product

Resources

About