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Christopoulou, E. B.; Georgakilas, A.; Koutchmy, S.

doi:10.1023/a:1010338927151

Cited by 35 publications

(41 citation statements)

References 14 publications

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“…2, bottom panel). In addition, Christopoulou et al (2001) observe limb spicules with clear parabolic paths with decelerations and maximum velocities similar to those for mottles and DFs.…”

Section: Discussionsupporting

confidence: 56%

Dynamic Fibrils Are Driven by Magnetoacoustic Shocks

Hansteen

Pontieu

Voort

et al. 2006

ApJ

278

342

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The formation of jets such as dynamic fibrils, mottles, and spicules in the solar chromosphere is one of the most important, but also most poorly understood, phenomena of the Sun's magnetized outer atmosphere. We use extremely high resolution observations from the Swedish 1 m Solar Telescope combined with advanced numerical modeling to show that in active regions these jets are a natural consequence of upwardly propagating slow-mode magnetoacoustic shocks. These shocks form when waves generated by convective flows and global p-mode oscillations in the lower lying photosphere leak upward into the magnetized chromosphere. We find excellent agreement between observed and simulated jet velocities, decelerations, lifetimes, and lengths. Our findings suggest that previous observations of quiet-Sun spicules and mottles may also be interpreted in light of a shockdriven mechanism.

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“…2, bottom panel). In addition, Christopoulou et al (2001) observe limb spicules with clear parabolic paths with decelerations and maximum velocities similar to those for mottles and DFs.…”

Section: Discussionsupporting

confidence: 56%

Dynamic Fibrils Are Driven by Magnetoacoustic Shocks

Hansteen

Pontieu

Voort

et al. 2006

ApJ

278

342

View full text Add to dashboard Cite

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“…Figure 1 and its associated movie reveal that these structures are associated with the regions of network magnetic fields which appear at the edges of granular cells (Nordlund et al 2009). It is now generally believed that the dark mottles are the disk counterparts of Type I spicules (Tsiropoula et al 1994a(Tsiropoula et al , 1994bTsiropoula & Schmieder 1997;Christopoulou et al 2001) and the RBEs are the disk counterparts of Type II spicules (Langangen et al 2008;De Pontieu et al 2011;Pereira et al 2012;Kuridze et al 2015). The mottles seen in the Hα line have mean velocities of the order of 20-40 km s −1 and lifetimes of 3-15 minutes (Tsiropoula et al 2012).…”

Section: Discussionmentioning

confidence: 99%

The Effects of Transients on Photospheric and Chromospheric Power Distributions

Samanta

Henriques

Banerjee

et al. 2016

ApJ

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We have observed a quiet-Sun region with the Swedish 1 m Solar Telescope equipped with the CRISP Imaging SpectroPolarimeter. High-resolution, high-cadence, Hα line scanning images were taken to observe different layers of the solar atmosphere from the photosphere to upper chromosphere. We study the distribution of power in different period bands at different heights. Power maps of the upper photosphere and the lower chromosphere show suppressed power surrounding the magnetic-network elements, known as "magnetic shadows." These also show enhanced power close to the photosphere, traditionally referred to as "power halos." The interaction between acoustic waves and inclined magnetic fields is generally believed to be responsible for these two effects. In this study we explore whether small-scale transients can influence the distribution of power at different heights. We show that the presence of transients, like mottles, Rapid Blueshifted Excursions (RBEs), and Rapid Redshifted Excursions (RREs), can strongly influence the power maps. The short and finite lifetime of these events strongly affects all power maps, potentially influencing the observed power distribution. We show that Doppler-shifted transients like RBEs and RREs that occur ubiquitously can have a dominant effect on the formation of the power halos in the quiet Sun. For magnetic shadows, transients like mottles do not seem to have a significant effect on the power suppression around 3 minutes, and wave interaction may play a key role here. Our high-cadence observations reveal that flows, waves, and shocks manifest in the presence of magnetic fields to form a nonlinear magnetohydrodynamic system.

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“…Several studies report that these phenomena fall back along the same trajectory or fade out (Beckers 1972;Suematsu 1998). Many on-disk filament-like features were identified as the counterpart of the limb spicules due to the similarities in their properties (Christopoulou et al 2001;Rouppe van der Voort et al 2007), and some were named "mottles" (Tsiropoula & Schmieder 1997). Coronal hole spicules are found to be taller than quiet Sun spicules, probably owing to the different configuration of the magnetic field of the two regions (Beckers 1972).…”

Section: Introductionmentioning

confidence: 99%

Can coronal hole spicules reach coronal temperatures?

Madjarska

Vanninathan

Doyle

2011

A&A

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Aims. The present study aims to provide observational evidence of whether coronal hole spicules reach coronal temperatures. Methods. We combine multi-instrument co-observations obtained with the SUMER/SoHO and with the EIS/SOT/XRT/Hinode. Results. The analysed three large spicules were found to be comprised of numerous thin spicules that rise, rotate, and descend simultaneously forming a bush-like feature. Their rotation resembles the untwisting of a large flux rope. They show velocities ranging from 50 to 250 km s −1 . We clearly associated the red-and blue-shifted emissions in transition region lines not only with rotating but also with rising and descending plasmas. Our main result is that these spicules although very large and dynamic, are not present in the spectral lines formed at temperatures above 300 000 K.Conclusions. In this paper we present the analysis of three Ca ii H large spicules that are composed of numerous dynamic thin spicules but appear as macrospicules in lower resolution EUV images. We found no coronal counterpart of these and smaller spicules. We believe that the identification of phenomena that have very different origins as macrospicules is due to the interpretation of the transition region emission, and especially the He ii emission, wherein both chromospheric large spicules and coronal X-ray jets are present. We suggest that the recent observation of spicules in the coronal AIA/SDO 171 Å and 211 Å channels probably comes from the existence of transition region emission there.

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Untitled

Cited by 35 publications

References 14 publications

Dynamic Fibrils Are Driven by Magnetoacoustic Shocks

Dynamic Fibrils Are Driven by Magnetoacoustic Shocks

The Effects of Transients on Photospheric and Chromospheric Power Distributions

Can coronal hole spicules reach coronal temperatures?

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