A Comparative Study between Eruptive X-Class Flares Associated with Coronal Mass Ejections and Confined X-Class Flares

By Yuming Wang, Jie Zhang. 2007

177 citations recorded by the source corpus.

We examine the two kinds of major energetic phenomena that occur in the solar atmosphere: eruptive and confined events. The former describes flares with associated coronal mass ejections (CMEs), while the latter denotes flares without associated CMEs. We find that about 90% of X-class flares are eruptive, but the remaining 10% are confined. To probe why the largest energy releases could be either eruptive or confined, we investigate four X-class events from each of the two types. Both sets of events are selected to have very similar intensities (X1.0 to X3.6) and duration (rise time under 13 minutes and decay time over 9 minutes) in soft X-ray observations, to reduce any bias due to flare size on CME occurrence. We find that the occurrence of eruption (or confinement) is sensitive to the displacement of the location of the energy release, defined as the distance between the flare site and the flux-weighted magnetic center of the source active region. The displacement is 6-17 Mm for confined events but as large as 22-37 Mm for eruptive events. This means that confined events occur closer to the magnetic center, while the eruptive events tend to occur close to the edge of active regions. We use the potential field source-surface model to infer the coronal magnetic field above the source active regions and calculate the flux ratio of low (<1.1 R☉) to high (≥1.1 R☉) corona. We find that the confined events have a lower ratio (<5.7) than the eruptive events (>7.1). These results imply that a stronger overlying arcade field may prevent energy releases in the low corona from being eruptive, resulting in flares, but without CMEs.

Subfields: Astronomy and Astrophysics, Geophysics

View Paper: https://www.semanticscholar.org/paper/0454cd1524bcea2508ca8b3bf98770e40f2bcbdf

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Citations in the corpus

ELECTRIC CURRENTS IN FLARE RIBBONS: OBSERVATIONS AND THREE-DIMENSIONAL STANDARD MODEL (2014, background): “The majority of X-class flares have been shown to originate from eruptive flares (Wang & Zhang 2007), making them important events to be understood.”
An Observational Overview of Solar Flares (2011, background): “A further pioneering paper by Gold & Hoyle (1960) had alreadydescribed a large-scale reconnection scenario that did not require a prior eruption, and many flares, even including some as powerful as the low X class (Wang & Zhang 2007) events,do not result from the open fields stretched out by a CME.”
WHY IS THE GREAT SOLAR ACTIVE REGION 12192 FLARE-RICH BUT CME-POOR? (2015, background): “Confined flares are rare for the more energetic events; only a dozen or so confined X-class flares have been analyzed (Schmahl et al. 1990; Feynman & Hundhausen 1994; Gaizauskas et al. 1998; Green et al. 2002; Wang & Zhang 2007; Liu 2008; Cheng et al. 2011; Chen et al. 2013; Liu et al. 2014a).”
Global Properties of Solar Flares (2011, background): “Wang and Zhang (2007) and Gopalswamy et al. (2009) find a total of 13 events over the interval 2000- 2005, with maximum GOES class X1.”
Space weather: the solar perspective (2021, background): “Therefore, confined flares may produce strong X-ray emission but, presumably due to a strong bipolar overlying coronal magnetic field configuration, are not related to the opening of the large-scale magnetic field (e.g., Wang and Zhang 2007; Sun et al. 2015; Thalmann et al. 2015).”
NEW SOLAR EXTREME-ULTRAVIOLET IRRADIANCE OBSERVATIONS DURING FLARES (2011, background): “Earlier studies revealed what appeared to be a steady increase in the fraction of CME-related events as a function of flare magnitude, ranging from ∼20% for C flares to ∼50% for M flares, and reaching close to 100% for X flares (Andrews 2003; Wang & Zhang 2007; Yashiro et al. 2005; Hudson 2011).”
Driving major solar flares and eruptions: A review (2008, background): “For example, Wang and Zhang (2007) find that 90% of 104 studied X-class flares are associated with eruptions, and Yashiro et al. (2005) find that the fraction of flares associated with CMEs increases from 20% for C3-9 flares to 100% for flares above X3.”
MAGNETIC PROPERTIES OF SOLAR ACTIVE REGIONS THAT GOVERN LARGE SOLAR FLARES AND ERUPTIONS (2016, background): “The studies by, e.g., Wang & Zhang (2007), Cheng et al. (2011), Kahler et al. (2015), Thalmann et al. (2015), and Sun et al. (2015) suggest a trend that CME-eruptive flares occur at larger distances from the AR centers and have larger “decay index” values (Kliem & Török 2006) than the non-eruptive…”