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Tsiropoula, G.; Madi, Charbel S.; Schmieder, B.

doi:10.1023/a:1005139705994

Cited by 35 publications

(52 citation statements)

References 3 publications

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“…The dark emission from the surge corresponds to the Hα +350 mÅ and +700 mÅ, while the bright to Hα−350 and −700. With the available information from the Hα line, it is not possible to derive (for instance, via cloud model; see Alissandrakis et al 1990 andSchmieder 1997) the full meaning of the bright and dark features.…”

Section: Resultsmentioning

confidence: 99%

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: Resultsmentioning

confidence: 99%

Explosive Events Associated With a Surge

Madjarska

Doyle

Pontieu

2009

ApJ

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“…The cloud model inversion, i.e., fitting the contrast profiles from Eq. (2) with the parameters S , τ 0 , λ c (v LOS /c), and Δλ D to the observed contrasts, has been used extensively, e.g., by Tsiropoula & Schmieder (1997); Al et al (2004); ; Tziotziou et al (2004), see also the recent review by Tziotziou (2007). A more refined method was employed by Tsiropoula (2000).…”

Section: Physical Parametersmentioning

confidence: 99%

Fast events and waves in an active region of the Sun observed in H$\mathsf{\alpha}$ with high spatial resolution

Nuño

González

Rodríguez

et al. 2008

A&A

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Context. We study the chromosphere of an active region of the Sun in the Hα line. Aims. The development of new instrumentation and new methods of data analysis allows to scrutinize the dynamics of the solar chromosphere with high spatial, spectral, and temporal resolution. The observations we present shed light on some magneto-dynamic processes occurring above an active region in the chromosphere. Methods. We took a time series of 55 min in Hα from AR 10875 at ϑ ≈ 36• . We used the "Göttingen" Fabry-Perot spectrometer at the Vacuum Tower Telescope, Observatorio del Teide/Tenerife, to obtain two-dimensional spectrograms in Hα. Adaptive optics and image reconstruction yielded a spatial resolution better than 0. 5 throughout the time sequence. From the wealth of structures, we selected areas of interest to study further, in detail, some ongoing processes. Results. A small straight surge developed aside of a pore with upward phase speed of 100 km s −1 and line-of-sight (LOS) velocity of 15 km s −1 . The surge retreated rapidly with LOS velocity of 45 km s −1 at its mouth. It underwent a rebound and fell back again. Two sympathetic mini-flares were observed that lasted only approximately 40 s, but showed strong Hα emission. We found magnetoacoustic waves in long fibrils as mainly short wave trains, short packets or pulses, i.e., solitary waves consisting of small (1 −2 ) blobs. They start at either end of the fibrils and travel with phase speeds of 12−14 km s −1 , i.e., close to the tube speed and approximately the sound velocity for sufficiently large magnetic field strengths. Some waves speed up to reach velocities of the order of 30 km s −1 . This is much lower than the expected Alfvén velocity of ≥200 km s −1 for reasonable magnetic field strengths and mass densities. We suggest that slow waves are not purely longitudinal, but possess gas velocities perpendicular to the direction of propagation of few km s −1 . Also, fast waves travel along sinuous lines suggesting entangled magnetic fields. They spread out along the direction of propagation in the course of their evolution and often vanish. We discuss the implications.

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“…Mottles are often considered as the disk representation of chromospheric spicules (Hansteen et al 2006;Rouppe van der Voort et al 2009). The exact nature of mottles remains the subject of an ongoing debate, with the majority of solar researchers agreeing that mottles and spicules are related, in the sense that they have similar temperatures, density profiles, widths, lengths, and lifetimes (Tsiropoula & Schmieder 1997;Zachariadis et al 2001). Chromospheric small-scale jet-like structures, such as mottles, spicules, and fibrils, play an important role in the mass balance of the solar atmosphere.…”

Section: Introductionmentioning

confidence: 99%

Transverse Oscillations in Chromospheric Mottles

Kuridze

Morton

Erdélyi

et al. 2012

ApJ

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A number of recent investigations have revealed that transverse waves are ubiquitous in the solar chromosphere. The vast majority of these have been reported in limb spicules and active region fibrils. We investigate long-lived, quiet-Sun, on-disk features such as chromospheric mottles (jet-like features located at the boundaries of supergranular cells) and their transverse motions. The observations were obtained with the Rapid Oscillations in the Solar Atmosphere instrument at the Dunn Solar Telescope. The data set is comprised of simultaneous imaging in the Hα core, Ca ii K, and G band of an on-disk quiet-Sun region. Time-distance techniques are used to study the characteristics of the transverse oscillations. We detect over 40 transverse oscillations in both bright and dark mottles, with periods ranging from 70 to 280 s, with the most frequent occurrence at ∼165 s. The velocity amplitudes and transverse displacements exhibit characteristics similar to limb spicules. Neighboring mottles oscillating in-phase are also observed. The transverse oscillations of individual mottles are interpreted in terms of magnetohydrodynamic kink waves. Their estimated periods and damping times are consistent with phase mixing and resonant mode conversion.

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Cited by 35 publications

References 3 publications

Explosive Events Associated With a Surge

Explosive Events Associated With a Surge

Fast events and waves in an active region of the Sun observed in H$\mathsf{\alpha}$ with high spatial resolution

Transverse Oscillations in Chromospheric Mottles

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