The association of transequatorial loops in the solar corona   with coronal mass ejection onset

Glover, Alexi; Harra, L. K.; Matthews, Sarah; Foley, C. A.

doi:10.1051/0004-6361:20021886

Cited by 22 publications

(22 citation statements)

References 23 publications

(32 reference statements)

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“…The shift in the type II burst position after 08:55 UT can be explained by the burst exiter meeting the active region belt/coronal streamer. An off-limb brightening in EUV has been reported by Glover et al (2003), when a coronal streamer was displaced by an eruption in connection with a disappearing transequatorial loop. Pohjolainen et al (2001) observed strong decimetric type IV continuum emission over an EUV dimming region during the May 2, 1998 event, and interpreted it as accelerated electrons in expanding large-scale loops associated with the CME.…”

Section: Early Disk Signatures Of the Development Of The Halo Cmementioning

confidence: 85%

Early signatures of large-scale field line opening

Pohjolainen¹,

Vilmer²,

Khan³

et al. 2005

A&A

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Abstract.A fast "halo"-type coronal mass ejection (CME) associated with a two-ribbon flare, GOES class M 1.3, was observed on February 8, 2000. Soft X-ray and EUV images revealed several loop ejections and one wave-like moving front that started from a remote location, away from the flare core region. A radio type-II burst was observed near the trajectory of the moving soft X-ray front, although association with the CME itself cannot be ruled out. Large-scale dimmings were observed in EUV and soft X-rays, both in the form of disappearing transequatorial loops. We can pinpoint the time and the location of the first large-scale field-line opening by tracing the electron propagation paths above the active region and along the transequatorial loop system, in which large-scale mass depletion later took place. The immediate start of a type-IV burst (interpreted as an upward moving structure) which was located over a soft X-ray dimming region, confirms that the CME had lifted off. We compare these signatures with those of another halo CME event observed on May 2, 1998, and discuss the possible connections with the "magnetic breakout" model.

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Section: Early Disk Signatures Of the Development Of The Halo Cmementioning

confidence: 85%

Early signatures of large-scale field line opening

Pohjolainen¹,

Vilmer²,

Khan³

et al. 2005

A&A

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“…If the halo CME-associated structures and events occur on the visible solar disk, they can be studied in detail. Recent studies have linked halo CMEs with EIT waves (Cliver et al 1999; Thompson et al 1999; The movie is only available in electronic form at http://www.edpsciences.org Biesecker et al 2002), soft X-ray and EUV dimmings (Sterling & Hudson 1997;Zarro et al 1999), Hα (Moreton) waves (Pohjolainen et al 2001), type II and type IV radio emission (Claßen & Aurass 2002;Caroubalos et al 2004), disappearing transequatorial loops (Khan & Hudson 2000;Pohjolainen et al 2001;Glover et al 2003), and oscillating filaments (Moreton 1964;Eto et al 2002;Ji et al 2002).…”

Section: Introductionmentioning

confidence: 99%

Non-thermal processes associated with rising structures and waves during a “halo” type CME

Lehtinen¹,

Pohjolainen²,

Karlický

et al. 2005

A&A

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We analyse structures and events connected with a flare-associated "halo" type coronal mass ejection (CME) observed on December 18, 2000. A GOES C7.0 class X-ray flare started at 11:02 UT in NOAA Active Region 9269, located at N14 E03. Yohkoh SXT observed slowly rising soft X-ray loops already some 5 min before flare start. Hα images show a two-ribbon flare, remote brightenings, and a partly disappearing filament near the active region. A metric radio precursor was observed to start at 11:06:30 UT, simultaneously with impulsive emission in hard X-rays and microwaves. The frequency-drifting precursor envelope was superposed with J-and reverse drift bursts. The radio bursts traced large-scale soft X-ray loop structures about 160 000 km away from the flare core, and hard X-ray emission was observed at the ends of some of these loops. The precursor emission points to a rising structure where electron acceleration takes place. Later on, a radio type II burst (signature of a propagating shock, driven either by an ejecta or a blast wave) and an EIT wave were observed. We conclude that possible sources for the rising structure and accelerator of electron beams are (1) large-scale loops that connect the flare core region and the precursor site in the close vicinity of two separate rising filaments, and (2) a growing shock that accelerates electrons along closed field lines until the multipolar field is opened and the CME is lifted off. As neither X-ray nor EUV ejecta could be observed whether in the direction of the type II burst or near the radio precursor, we find some support for the shock wave scenario.

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“…We analyze ISOON H full-disk images and SOHO EIT/Michelson Doppler Imager (MDI) observations for a largescale event on 2002 December 19 involving a halo CME that was associated with an erupting transequatorial loop ( TL; see Delannée & Aulanier [1999], Khan & Hudson [2000], and Glover et al [2003] for previously reported examples of such eruptions). The new aspect of the 2002 December 19 event revealed by highcadence, high spatial resolution, ISOON H data is a series of sequential chromospheric brightenings (SCBs) that originate near the flare site and propagate across the solar equator along the path of the erupting TLs.…”

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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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The association of transequatorial loops in the solar corona with coronal mass ejection onset

Cited by 22 publications

References 23 publications

Early signatures of large-scale field line opening

Early signatures of large-scale field line opening

Non-thermal processes associated with rising structures and waves during a “halo” type CME

Sequential Chromospheric Brightenings beneath a Transequatorial Halo Coronal Mass Ejection

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