Dynamic evolution of recurrent mass ejections observed in H? and Civ lines

Schmieder, B.; Mein, P.; Martres, M. J.; Tandberg-Hanssen, E.

doi:10.1007/bf00154814

Cited by 34 publications

(18 citation statements)

References 11 publications

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“…The observations presented here emphasise that the magnetic reconnection, which occurs between the emerging flux and the pre-existing coronal field in the CME triggering process, takes place intermittently, rather than continually, as implied by the repetitive behaviour of the Hα surges. Such a repetitive behaviour of Hα surges, with a period of ∼1 h, was reported by Schmieder et al (1984). The repetitive reconnection might be modulated by MHD waves in a way similar to that proposed by Chen & Priest (2006).…”

Section: Global Picturesupporting

confidence: 71%

SOHO/SUMER observations of prominence oscillation before eruption

Chen¹,

Innes

Solanki

2008

A&A

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Context. Coronal mass ejections (CMEs), as a large-scale eruptive phenomenon, often reveal some precursors in the initiation phase, e.g., X-ray brightening, filament darkening, etc., which are useful for CME modelling and space weather forecasting. Aims. With the Solar Ultraviolet Measurements of Emitted Radiation (SUMER) spectroscopic observations of the 2000 September 26 CME, we propose another precursor for CMEs, namely, long-time prominence oscillations. Methods. We observed the prominence oscillation-and-eruption event by ground-based Hα telescopes and space-borne white-light, EUV imaging, and spectroscopic instruments. In particular, the SUMER slit was observing the prominence in a sit-and-stare mode.Results. The observations indicate that a siphon flow was moving from the proximity of the prominence to a site at a projected distance of 270 , which was followed by repetitive Hα surges and continual prominence oscillations. The oscillation lasted 4 hours before the prominence erupted as a blob-like CME. The analysis of the multiwavelength data indicates that the whole series of processes fits well into the emerging flux trigger mechanism for CMEs. In this mechanism, emerging magnetic flux drives a siphon flow due to increased gas pressure where the background polarity emerges. It also drives Hα surges through magnetic reconnection where the opposite polarity emerges. The magnetic reconnection triggers the prominence oscillations, as well as its loss of equilibrium, which finally leads to the eruption of the prominence. It is also found that the reconnection between the emerging flux and the pre-existing magnetic loop proceeds in an intermittent, probably quasi-periodic, way.

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Section: Global Picturesupporting

confidence: 71%

SOHO/SUMER observations of prominence oscillation before eruption

Chen¹,

Innes

Solanki

2008

A&A

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“…Similar ejection phenomena at other wavelengths, such as UV, EUV and X-ray jets, have also been studied by a number of authors (Schmahl 1981;Schmieder et al 1984;Švestka et al 1990;Shibata et al 1992;Schmieder et al 1993;Shimojo et al 1996;Zhang et al 2000;Asai et al 2001). Regarding the question about the temporal and spatial relationships between surges and jets, some authors have given different, and even opposite results (see Rust et al 1977;Schmieder et al 1988;Shibata et al 1992).…”

Section: Introductionmentioning

confidence: 70%

Observations of H_αsurges and ultraviolet jets above satellite sunspots

Chen

Jiang²,

Ma³

2007

A&A

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Aims.To know more about the physical origin of surges and jets, we investigated seven successive surge events, which occurred above the satellite sunspots of active region NOAA 10720 on 2005 January 15. Methods. Using data from the Transition Region and Coronal Explorer (TRACE), Big Bear Solar Observatory (BBSO) and Solar and Heliospheric Observatory (SOHO), we present a detailed study of the surges and their relations with the associated small arch filament, UV jets, flares and photospheric longitudinal magnetic fields. Results. The seven H α surges we studied repeatedly occurred where the photospheric longitudinal fluxes of opposite magnetic polarities emerged, converged and were canceled by each other. Correspondingly, a small satellite spot emerged, decayed and disappeared during a period of about 2 hours in the white-light observations. In morphology, all surges displayed almost linear ejective structures. Their dynamic properties, such as the transverse velocity, projected maximum length and lifetime, varied in wide ranges. They are 30-200 km s −1 , 38 000-220 000 km and from several to tens of minutes, respectively. Correspondingly, the intensities of their correlated microflares were different too. The surges of major velocities or maximum lengths seemed to be accompanied by processes of more energy release. Prior to these surge events, a small H α arch filament connecting the opposite flux elements was found at the base region. Instead of erupting completely, it gradually disappeared during the surges. Its role in the surge activities is very like a bipolar flux, which contained the cool plasma and reconnected with the ambient magnetic fields. In 1600 Å, three surge events exhibited the composite structures of bright jets and nearby small flaring loops, which provides direct evidence of magnetic reconnection origin of the surges. A careful comparison revealed that the ends of the arch filament, the UV jets and the small flaring loops just corresponded to the interacting longitudinal fluxes in the photosphere. Conclusions. These observational results support the magnetic reconnection model of surges and jets.

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“…During the descending stage, the matter in a surge falls down along almost the same path that it took in the ascending phase. Surges usually show a strong trend to recurrence , such that they appear at the same position many times with a duration of 10-20 min and a repetition rate of an hour (Tandberg-Hanssen 1977;Schmieder et al 1984). The rotational or helical motions were, on occasions, also observed in surge activity (Canfield et al 1996;Jibben & Canfield 2004).…”

Section: Introductionmentioning

confidence: 99%

Study of the first productive active region in solar cycle 24

Zhang

et al. 2012

A&A

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Context. The Sun is very quiet with less sunspots and activity since the beginning of solar cycle 24. However, the active region (AR) 11 045 emerged on February 5, 2010, is associated with 43 (8 M-and 35 C-class) flares, 53 coronal mass ejections (CMEs), 29 filament eruptions, 19 extreme ultraviolet (EUV) waves and abundant jets, indicating that this AR is the first productive one of solar cycle 24. Aims. We study the AR evolution and its associated activities, and also their relationships, to understand this productive AR. Methods. We used SOHO/MDI magnetograms to study the magnetic fields, STEREO/SECCHI images to explore the activities, and GOES measurements to investigate the soft X-ray flux of the AR. Results. During the AR evolution, six pairs of main magnetic fields emerged, and 93.1% flares and 82.75% filament eruption occurred in the emergence and stable phases of the magnetic flux. However, 43.4% CMEs occurred in the decaying phase, even though there were less flares. An example is given to show that an event is related to a flare, a filament eruption, a CME and an EUV wave from inner corona to outer corona in space, and the filament eruption and EUV wave occur near the peak time of the flare. Among the 29 filament eruptions, 79.3% are associated with CMEs, as well as 58.6%, associated with flares, and 34.5%, associated with EUV waves. During the 12-day active phase, 575 jets are detected with a daily occurrence rate of 49.3. This is the first time that so many jets have been identified in one AR, implying at least 575 lower magnetic reconnection processes during the AR evolution. We statistically studied these jets along with the AR evolution, and noticed that the jets mostly occurred surrounding the emerging flux. We also investigated the spatio-temporal relationships between the jets and the flares, and find that the jets are usually rooted around the flare cores, and the soft X-ray flux is inverse correlated with the number of the jets, especially during the beginning 9 days since the AR emergence. In comparison with AR 11045, we studied the other newly emerging AR 11045, and obtained similar results. The relationships between the jets and the flares may well represent a scenario of two-step magnetic reconnection. Using schematic diagrams, we explain the remarkable magnetic field emergence, cancelation and shear motion of AR 11045, and its associated activities.

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Dynamic evolution of recurrent mass ejections observed in H? and Civ lines

Cited by 34 publications

References 11 publications

SOHO/SUMER observations of prominence oscillation before eruption

SOHO/SUMER observations of prominence oscillation before eruption

Observations of H_αsurges and ultraviolet jets above satellite sunspots

Study of the first productive active region in solar cycle 24

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Dynamic evolution of recurrent mass ejections observed in H? and Civ lines

Cited by 34 publications

References 11 publications

SOHO/SUMER observations of prominence oscillation before eruption

SOHO/SUMER observations of prominence oscillation before eruption

Observations of Hαsurges and ultraviolet jets above satellite sunspots

Study of the first productive active region in solar cycle 24

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Observations of H_αsurges and ultraviolet jets above satellite sunspots