Untitled

Kjeldseth-Moe, O.; Brekke, P.

doi:10.1023/a:1005031711233

Cited by 72 publications

(47 citation statements)

References 26 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Moreover, when the pulses are less concentrated near the loop's footpoints, the evolution produces hotter loops and progressively less flat temperature profiles in the upper parts of the loop along with an appreciably reduced number of the temperature depressions. This latter feature is consistent with the observational lack of strong variability at very high coronal temperatures (Kjeldseth-Moe & Brekke 1998;Schrijver 2001).…”

Section: Resultssupporting

confidence: 90%

“…These depressions may involve strong temperature variations, most of them from $1:5 ; 10 6 down to $10 4 K, which may last from about 3 to 10 minutes, and their number may be sensitive to the details of the spatiotemporal distribution of the microscale heating. MSE05 concluded that this behavior may be related to the observed rapid time variability of coronal loops inferred from SOHO Coronal Diagnostic Spectrometer observations in active regions of the solar atmosphere (Kjeldseth-Moe & Brekke 1998;Schrijver 2001). Moreover, when the pulses are less concentrated near the loop's footpoints, the evolution produces hotter loops and progressively less flat temperature profiles in the upper parts of the loop along with an appreciably reduced number of the temperature depressions.…”

Section: Resultsmentioning

confidence: 97%

See 1 more Smart Citation

Intermittent Coronal Loop Oscillations by Random Energy Releases

Mendoza-Briceño

Erdélyi

2006

ApJ

View full text Add to dashboard Cite

High-resolution observations by the SOHO and TRACE spacecraft have confirmed the existence of coronal loop oscillations and waves. In a recent work, Mendoza-Briceño et al. studied the heating response of coronal plasma to energy pulses randomly distributed in time and space along coronal loops. In this paper we focus on the oscillatory patterns and other features, such as cool gas blobs traveling along the loop, during the evolution of spatiotemporal randomly heated flux tubes in the corona. The nature of these oscillatory patterns is investigated using wavelet analysis. Periodic features, such as wave packets, with periods of 150 Y220, 500 Y 600, and 800 Y1000 s are found. It is also found that the periods increase with the loop length and decrease with the length of the loop segments along which the pulses are injected. On the other hand, the randomly driven intermittent cool plasma blobs that propagate from one footpoint to the other are analyzed. Although plenty of coronal loop oscillations are detected by the cohort of the current high-resolution satellites, there are more controversial observational evidences about the predicted cold plasma blobs.

show abstract

Section: Resultssupporting

confidence: 90%

Section: Resultsmentioning

confidence: 97%

Intermittent Coronal Loop Oscillations by Random Energy Releases

Mendoza-Briceño

Erdélyi

2006

ApJ

View full text Add to dashboard Cite

show abstract

“…One is the contribution of dynamically evolving structures to transition region emission. Recent observations with high spatial and temporal resolutions indicate that dynamically evolving structures provide a nonnegligible contribution to transition region emission (Korendyke et al 1995 ;Yun et al 1998 ;Kjeldseth-Moe & Brekke 1998 ;Pike & Mason 1998 ;Chae et al 1998 ;Berghmans et al 1998 ;Benz & Krucker 1998). Transition region emission lines have also been observed to show pervasive redshifts through several temperature regimes (Dere 1982 ;Gebbie et al 1981).…”

Section: Heating the L Ower T Ransition Regionmentioning

confidence: 99%

“…In lines emitted from ions with temperatures ranging from the lower transition region (20,000 K) through the corona (106 K), loops have been directly observed, or inferred to exist, above photospheric magnetic bipoles (Pre s & Phillips 1999 ;Kankelborg et al 1996Kankelborg et al , 1997Falconer et al 1996Falconer et al , 1998Dowdy 1993 ;Fontenla et al 1989 ;Mariska 1986 ;Bonnet 1980) for a wide range of size scales. Recent observations with high temporal and spatial resolution show that many of these loop structures are transient, dynamically evolving structures (see, for example, Kjeldseth-Moe & Brekke 1998 ;Yun et al 1998 ;Wang et al 1997 ;Korendyke et al 1995 ;Strong 1994). Nevertheless, a large number of loop structures have been observed to persist for periods of time that are long, compared to radiative and conductive cooling timescales for a fully ionized plasma, without undergoing dramatic changes in either their luminosities or structures (see, for example, Craig & McClymont 1981 ;Veseckey, Antiochos, & Underwood 1979 ;Gerassimenko et al 1978).…”

Section: Introductionmentioning

confidence: 99%

Observation and Modeling of the Solar Transition Region. II. Identification of New Classes of Solutions of Coronal Loop Models

Oluseyi

Walker

Santiago

et al. 1999

ApJ

View full text Add to dashboard Cite

In the present work we undertake a study of the quasi-static loop model and the observational consequences of the various solutions found. We obtain the most general solutions consistent with certain initial conditions. Great care is exercised in choosing these conditions to be physically plausible (motivated by observations). We show that the assumptions of previous quasi-static loop models, such as the models of Rosner, Tucker, & Vaiana (RTV) and Veseckey, Antiochos, & Underwood, (VAU) are not necessarily valid for small loops at transition region temperatures. We Ðnd three general classes of solutions for the quasi-static loop model, which we denote radiation-dominated loops, conduction-dominated loops, and classical loops. These solutions are then compared with observations. Departures from the classical scaling law of RTV are found for the solutions obtained. It is shown that loops of the type that we model here can make a signiÐcant contribution to lower transition regions emission via thermal conduction from the upper transition region.

show abstract

“…They argue these disturbances are not caused by mass-flows along the loops because that would require velocity values considerably larger than the measured values. Kjeldseth-Moe & Brekke (1998) Robbrecht et al (1999) and which will also be studied in this report. Also more recently De Moortel et al (2000) reported on similar propagating oscillations in large diffuse coronal loops, using TRACE data.…”

Section: Introductionmentioning

confidence: 99%

Slow magnetoacoustic waves in coronal loops: EIT and TRACE

Robbrecht

Verwichte

Berghmans

et al. 2001

A&A

151

113

View full text Add to dashboard Cite

Abstract. On May 13, 1998 the EIT (Extreme ultraviolet Imaging Telescope) on board of SoHO (Solar and Heliospheric Observatory) and TRACE (Transition Region And Coronal Explorer) instruments produced simultaneous high cadence image sequences of the same active region (AR 8218). TRACE achieved a 25 s cadence in the Fe ix (171Å) bandpass while EIT achieved a 15 s cadence (operating in "shutterless mode", SoHO JOP 80) in the Fe xii (195Å) bandpass. These high cadence observations in two complementary wavelengths have revealed the existence of weak transient disturbances in an extended coronal loop system. These propagating disturbances (PDs) seem to be a common phenomenon in this part of the active region. The disturbances originate from small scale brightenings at the footpoints of the loops and propagate along the loops. The projected propagation speeds roughly vary between 65 and 150 km s −1 for both instruments which is close to and below the expected sound speed in the coronal loops. The measured slow magnetoacoustic propagation speeds seem to suggest that the transients are sound (or slow) wave disturbances. This work differs from previous studies in the sense that it is based on a multi-wavelength observation of an entire loop bundle at high cadence by two EUV imagers. The observation of sound waves along the same path shows that they propagate along the same loop, suggesting that loops contain sharp temperature gradients and consist of either concentric shells or thin loop threads, at different temperatures.

show abstract

Untitled

Cited by 72 publications

References 26 publications

Intermittent Coronal Loop Oscillations by Random Energy Releases

Intermittent Coronal Loop Oscillations by Random Energy Releases

Observation and Modeling of the Solar Transition Region. II. Identification of New Classes of Solutions of Coronal Loop Models

Slow magnetoacoustic waves in coronal loops: EIT and TRACE

Contact Info

Product

Resources

About