Transition region small-scale dynamics as seen by SUMER on SOHO

Teriaca, L.; Banerjee, D.; Falchi, A.; Doyle, J. G.; Madjarska, M. S.

doi:10.1051/0004-6361:20040503

Cited by 82 publications

(87 citation statements)

References 51 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…From the examples shown as EE1 and EE2, which are much smaller than the macrospicule, we estimate a value of a c = 7 km s −2 assuming v = ± 40 km s −1 and r as about the slit size of 0.3 . Similar values can be expected if we adopt the typical parameters mentioned by Teriaca et al (2004), namely a diameter of 2 and a velocity of 150 km s −1 . These violent motions could contribute to the solar wind acceleration (Pasachoff et al 1968).…”

Section: Discussionsupporting

confidence: 84%

“…Typical EEs were found to be short-lived (60 s to 200 s), small-scale (1500 km to 2500 km), high-velocity (±50 km s −1 to ±150 km s −1 ) flows that occur very frequently, sometimes in bursts. Teriaca et al (2004) estimated an average size of 1800 km, a birth rate of 2500 s −1 , and 30 000 events at any one time on the entire Sun. In the classical view EEs are seen as bidirectional jets that are generated by a Petschek-type reconnection event (Innes et al 1997) high up in the TR with a collimated upflowing component -blueshifted in TR emissionand with a downflowing, redshifted component at some angle to the line-of-sight (LOS).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Spectroscopic evidence for helicity in explosive events

Curdt

Tian

2011

A&A

View full text Add to dashboard Cite

Aims. We report spectroscopic observations in support of a novel view of transition region explosive events, observations that lend empirical evidence that at least in some cases explosive events may be nothing else but spinning narrow spicule-like structures. Methods. Our spectra of textbook explosive events with simultaneous Doppler flow of a red and a blue component are extreme cases of high spectroscopic velocities that lack apparent motion, to be expected if interpreted as a pair of collimated, linearly moving jets. The awareness of this conflict led us to the alternative interpretation of redshift and blueshift as a spinning motion of a small plasma volume. In contrast to the bidirectional jet scenario, a small volume of spinning plasma would be fully compatible with the observation of flows without detectable apparent motion. We suspect that these small volumes could be spicule-like structures and try to find evidence for this. We show observations of helical motion in macrospicules and argue that these features -if scaled down to a radius comparable to the slit size of a spectrometer -should have a spectroscopic signature similar to that observed in explosive events, which is admittedly not easily detectable by imagers. Despite of this difficulty, evidence of helicity in spicules has been reported in the literature. This led us to the new insight that the same narrow spinning structures may be the drivers in both cases, structures that imagers observe as spicules and that in spectrometers cross the slit and are seen as explosive events. Results. We arrive at a concept that supports the idea that explosive events and spicules are different manifestations of the same helicity-driven scenario. In contrast to the conventional view of explosive events as linear bidirectional jets that are triggered by a reconnection event in the transition region, this new interpretation is compatible with the observational results. Consequently, in this case a photospheric or subphotospheric trigger has to be assumed. Conclusions. We suggest that explosive events/spicules are to be compared to the unwinding of a loaded torsional spring.

show abstract

Section: Discussionsupporting

confidence: 84%

Section: Introductionmentioning

confidence: 99%

Spectroscopic evidence for helicity in explosive events

Curdt

Tian

2011

A&A

View full text Add to dashboard Cite

show abstract

“…The conclusion from this observation is that explosive events do not contribute significantly to the energy balance of the corona. The same conclusion was reached by Teriaca et al (2002bTeriaca et al ( , 2004.…”

Section: Explosive Eventssupporting

confidence: 78%

“…Further investigations with the help of the 17.1 nm and 19.5 nm passbands of TRACE and model calculations yielded consistent density and temperature values in coronal loops. Evidence was provided that hot (≈5 MK) and cold (≈2 × 10 5 K) fibrils together form a loop (Testa et al 2002). A disturbance observed by TRACE at one footpoint of a cold loop led to a strong red-shifted emission of N V at 123.8 nm emission at the other footpoint (Doyle et al 2006a).…”

Section: The Equatorial Corona Coronal Loops and The Slow Solar Windmentioning

confidence: 99%

Observations of the Sun at Vacuum-Ultraviolet Wavelengths from Space. Part II: Results and Interpretations

et al. 2007

View full text Add to dashboard Cite

In Part I of this review, the concepts of solar vacuum-ultraviolet (VUV) observations were outlined together with a discussion of the space instrumentation used for the investigations. A section on spectroradiometry provided some quantitative results on the solar VUV radiation without considering any details of the solar phenomena leading to the radiation. Here, in Part II, we present solar VUV observations over the last decades and their interpretations in terms of the plasma processes and the parameters of the solar atmosphere, with emphasis on the spatial and thermal structures of the chromosphere, transition region and corona of the quiet Sun. In addition, observations of active regions, solar flares and prominences are included as well as of small-scale events. Special sections are devoted to the elemental composition of the solar atmosphere and theoretical considerations on the heating of the corona and the generation of the solar wind.

show abstract

“…Teriaca, Madjarska, and Doyle (2002) analysed spectral lines to determine whether or not transition region explosive events have coronal counterparts. Teriaca et al (2004) found cases where supersonic flows in small loops were associated with non-Gaussian line profiles. More recently, Madjarska, Doyle, and de Pontieu (2009) have demonstrated that explosive events and other transient phenomena may be the same processes, but observed in different ways.…”

Section: Introductionmentioning

confidence: 95%

Forward Modelling of a Brightening Observed by AIA

et al. 2015

View full text Add to dashboard Cite

A comprehensive understanding of the different transient events is necessary for any eventual solution of the coronal heating problem. We present a cold loop whose heating caused a short-lived small-scale brightening that was observed by AIA. The loop was simulated using an adaptive hydrodynamic radiation code that considers the ions to be in a state of non-equilibrium. Forward modelling was used to create synthetic AIA intensity plots, which were tested against the observational data to confirm the simulated properties of the event. The hydrodynamic properties of the loop were determined. We found that the energy released by the heating event is within the canonical energy range of a nanoflare.

show abstract

Transition region small-scale dynamics as seen by SUMER on SOHO

Cited by 82 publications

References 51 publications

Spectroscopic evidence for helicity in explosive events

Spectroscopic evidence for helicity in explosive events

Observations of the Sun at Vacuum-Ultraviolet Wavelengths from Space. Part II: Results and Interpretations

Forward Modelling of a Brightening Observed by AIA

Contact Info

Product

Resources

About