The H<sub><i>α</i></sub>surges and EUV jets from magnetic flux emergences and cancellations

Jiang, Yong; Chen, Huadong; Li, K. J.; Shen, Yuandeng; Yang, Liheng

doi:10.1051/0004-6361:20053954

Cited by 132 publications

(90 citation statements)

References 33 publications

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“…The TRACE contours overplotted on the Hα images help to cross-correlate the feature as seen in TRACE with the dark and bright Hα features from the surge and its footpoints. Jiang et al (2007) presented in great detail the relation between Hα surges, EUV and X-ray jets, which resemble very much the event analyzed here (Figure 4). They concluded that each surge consisted of a cool Hα component and hot, EUV or soft X-ray component which showed different evolution in space and time.…”

Section: Resultssupporting

confidence: 54%

Explosive Events Associated With a Surge

Madjarska

Doyle

Pontieu

2009

ApJ

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The solar atmosphere contains a wide variety of small-scale transient features. Here, we explore the interrelation between some of them such as surges, explosive events, and blinkers via simultaneous spectral and imaging data taken with the TRACE imager, the SUMER and Coronal Diagnostics Spectrometer (CDS) on board SOHO, and Swedish Vacuum Solar Telescope La Palma. The features were observed in spectral lines with formation temperatures from 10,000 K to 1 MK and with the TRACE Fe ix/x 171 Å filter. The Hα filtergrams were taken in the wings of the Hα 6365 Å line at ±700 mÅ and ±350 mÅ. The alignment of all data in both time and solar XY shows that SUMER line profiles, which are attributed to explosive events, are due to a surge phenomenon. The surge's up-and downflows, which often appear simultaneously, correspond to the blue-and redshifted emission of the transition region N v 1238.82 Å and O v 629.77 Å lines as well as radiance increases of the C i, S i, and S ii and Si ii chromospheric lines. Some parts of the surge are also visible in the TRACE 171 Å images which could suggest heating to coronal temperatures. The surge is triggered, most probably, by one or more Elerman bombs which are best visible in Hα ± 350 Å but were also registered by TRACE Fe ix/x 171 Å and correspond to a strong radiance increase in the CDS Mg ix 368.07 Å line. With the present study, we demonstrate that the division of small-scale transient events into a number of different subgroups, for instance explosive events, blinkers, spicules, surges or just brightenings, is ambiguous, implying that the definition of a feature based only on either spectroscopic or imaging characteristics as well as insufficient spectral and spatial resolution can be incomplete.

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Section: Resultssupporting

confidence: 54%

Explosive Events Associated With a Surge

Madjarska

Doyle

Pontieu

2009

ApJ

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“…The authors depicted a helical structure of a jet, which showed signs of untwisting with the jet initially ascending slowly with ≈10−20 km s −1 and then suddenly accelerating to velocities higher than 300 km s −1 . Helical structures in jets have also been reported by Shimojo et al (1996), Jiang et al (2007), and Nisticò et al (2009). Kamio et al (2010) studied the relation of so-called macrospicules in He ii 304 Å and an X-ray jet.…”

Section: Introductionmentioning

confidence: 83%

Dynamics and plasma properties of an X-ray jet from SUMER, EIS, XRT, and EUVI A & B simultaneous observations

Madjarska

2010

A&A

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Context. Small-scale transient phenomena in the quiet Sun are believed to play an important role in coronal heating and solar wind generation. One of them, called "X-ray jet", is the subject of our study. Aims. We intend to investigate the dynamics, evolution, and physical properties of this phenomenon. Methods. We combine multi-instrument observations obtained simultaneously with the SUMER spectrometer onboard SoHO, with EIS and XRT onboard Hinode, and with EUVI/SECCHI onboard the Ahead and Behind STEREO spacecrafts. We derive plasma parameters such as temperatures and densities as well as dynamics by using spectral lines formed in the temperature range from 10 000 K to 12 MK. We also use an image difference technique to investigate the evolution of the complex structure of the studied phenomenon.Results. With the available unique combination of data we were able to establish that the formation of a jet-like event is triggered by not one, but several energy depositions, which are most probably originating from magnetic reconnection. Each energy deposition is followed by the expulsion of pre-existing or newly reconnected loops and/or collimated flow along open magnetic field lines. We derived in great detail the dynamic process of X-ray jet formation and evolution. For the first time we also found spectroscopically a temperature of 12 MK (Fe xxiii 263.76 Å) and density of 4 × 10 10 cm −3 in the quiet Sun, obtained from a pair of Fe xii lines with a maximum formation temperature of 1.3 × 10 6 K, in an energy deposition region. We point out a problem concerning an uncertainty in using the SUMER Mg x 624.9 Å line for coronal diagnostics. We clearly identified two types of up-flow: one collimated up-flow along open magnetic field lines and a plasma cloud formed from the expelled BP loops. We also report a cooler down-flow along closed magnetic field lines. A comparison is made with a model developed by Moreno-Insertis et al. (2008).

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“…The spatial relationship between the jets and surges is controversial. It has been observed that surges are adjacent to jets (Canfield et al 1996;Chae et al 1999;Jiang et al 2007). In our study, the hot jets observed in the AIA filters were associated with recurrent cool surges that were observed and covered during their whole lifetimes in the Hα line center (Wang et al 2014).…”

Section: Relationship Between Jets and Surgesmentioning

confidence: 99%

“…It is widely accepted that coronal jets are heated by magnetic reconnection between emerging flux and the pre-existing magnetic fields with opposite polarity (Shibata & Uchida 1986;Yokoyama & Shibata 1996;Moreno-Insertis et al 2008;Török et al 2009;Moreno-Insertis & Galsgaard 2013). According to the numerical simulations of Yokoyama & Shibata (1996), there are hot, compact microflares at their footpoints (Krucker et al 2011;Zhang & Ji 2013) and cool Hα surges adjacent to the hot jets (Schmieder et al 1995;Canfield et al 1996;Liu & Kurokawa 2004;Jiang et al 2007;Liu 2008;Nelson & Doyle 2013). The EUV emissions from a hot jet were observed to be absorbed by the foreground cool surge, which resulted in EUV dimming behind the leading edge of the jet (Zhang & Ji 2014).…”

Section: Introductionmentioning

confidence: 99%

Blobs in recurring extreme-ultraviolet jets

Zhang

2014

A&A

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Context. Coronal jets are one type of ubiquitous small-scale activity that is caused by magnetic reconnection in the solar corona. They are often associated with cool surges in the chromosphere. Aims. In this paper, we report our discovery of blobs in the recurrent and homologous jets that occurred at the western edge of the NOAA active region 11259 on 2011 July 22. Methods. The jets were observed in the seven extreme-ultraviolet (EUV) filters of the Atmospheric Imaging Assembly instrument aboard the Solar Dynamics Observatory. Using the base-difference images of the six filters (94, 131, 171, 211, 193, and 335 Å), we carried out the differential emission measure (DEM) analyses to explore the thermodynamic evolutions of the jets. The jets were accompanied by cool surges observed in the Hα line center of the ground-based telescope in the Big Bear Solar Observatory. Results. The jets that had lifetimes of 20−30 min recurred at the same place for three times with an interval of 40−45 min. Interestingly, each of the jets intermittently experienced several upward eruptions at the speed of 120−450 km s −1 . After reaching the maximum heights, they returned back to the solar surface, showing near-parabolic trajectories. The falling phases were more evident in the low-T filters than in the high-T filters, indicating that the jets experienced cooling after the onset of eruptions. We identified bright and compact blobs in the jets during their rising phases. The simultaneous presence of blobs in all the EUV filters were consistent with the broad ranges of the DEM profiles of the blobs (5.5 ≤ log T ≤ 7.5), indicating their multi-thermal nature. The median temperatures of the blobs were ∼2.3 MK. The blobs that were ∼3 Mm in diameter had lifetimes of 24−60 s. Conclusions. To our knowledge, this is the first report of blobs in coronal jets. We propose that these blobs are plasmoids created by the magnetic reconnection as a result of tearing-mode instability and are ejected out along the jets.

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The H_αsurges and EUV jets from magnetic flux emergences and cancellations

Cited by 132 publications

References 33 publications

Explosive Events Associated With a Surge

Explosive Events Associated With a Surge

Dynamics and plasma properties of an X-ray jet from SUMER, EIS, XRT, and EUVI A & B simultaneous observations

Blobs in recurring extreme-ultraviolet jets

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The Hαsurges and EUV jets from magnetic flux emergences and cancellations

Cited by 132 publications

References 33 publications

Explosive Events Associated With a Surge

Explosive Events Associated With a Surge

Dynamics and plasma properties of an X-ray jet from SUMER, EIS, XRT, and EUVI A & B simultaneous observations

Blobs in recurring extreme-ultraviolet jets

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Product

Resources

About

The H_αsurges and EUV jets from magnetic flux emergences and cancellations