Coronal loops: Isothermal OR multithermal?

Schmelz, J. T.; Cirtain, Jonathan; Beene, J. E.; Blevins, H. T.; Ellis, Donald W.; Medlin, Drew; Nasraoui, K.; Nevels, C. R.

doi:10.1016/s0273-1177(03)00314-4

Cited by 7 publications

(5 citation statements)

References 46 publications

(33 reference statements)

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“…Moreover it has also been suggested that the coronal magnetic loops are in fact collections of very thin magnetic ropes bundled together (e.g. Martens et al 2002;Schmelz et al 2003Schmelz et al , 2005Aschwanden 2005;Aschwanden & Nightingale 2005). It is therefore important to understand how the interaction of these neighbouring loops affects the oscillations and damping of coronal loops.…”

Section: Introductionmentioning

confidence: 99%

Resonantly damped oscillations of two coronal loops

Robertson

2010

A&A

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Transverse oscillations of coronal magnetic loops are routinely observed during the space missions. Since the first observation these oscillations were interpreted in terms of kink oscillations of magnetic tubes. Sometimes collective oscillations of two or more coronal loops are observed. This makes the development of theory of collective oscillations of a few parallel magnetic tubes desirable. Another reason for the development of this theory is that there are evidences that at least some coronal loops are not monolithic but consist of many thin magnetic threads. In this paper the linear theory of resonant damping of kink oscillations of two parallel magnetic tubes is developed. Two small parameters, the ratio of the distance between the tubes to the tube length and the ratio of thickness of regions with varying density to the tube radius, are used to obtain the asymptotic expression for the decrement. This expression is calculated explicitly in a particular case of two identical tubes. The dependence of damping time on the separation distance between the tubes and on the density contrast is investigated. In particular, we obtained that the interaction between the tubes reduces the efficiency of resonant absorption.

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Section: Introductionmentioning

confidence: 99%

Resonantly damped oscillations of two coronal loops

Robertson

2010

A&A

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“…There is evidence from analysis of solar loops seen in the Transition Region and Coronal Explorer (TRACE; Aschwanden et al 2001) that such loops might be more isothermal than those in the RTV model. However, Schmelz et al (2003) suggested that the apparent uniform temperature loops derived from this method may be a by-product of the filter ratio method used in the analysis. Comparisons of EM distributions for the UMa and those from the active Sun show that the morphology is very similar to that for the brightest solar active regions .…”

Section: Discussionmentioning

confidence: 99%

Stellar Coronal Abundances at Intermediate‐Activity Levels: ξ UMa

Ball

Drake

Lin

et al. 2005

ApJ

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We present an analysis of Chandra High Energy Transmission Grating (HETG) spectra of the corona of the critical intermediate-activity, quadruple stellar system UMa. Using the maximum A/B subsystem separation in 2001, we attempted to resolve for the first time in X-rays the two components using the HETG Medium Energy Grating (MEG). We found the Aa component of the system to be at least 2 orders of magnitude fainter than the Bb component. We used the Markov Chain Monte Carlo method to reconstruct differential emission measures (DEMs) and abundances and discuss first ionization potential (FIP) issues. The reconstructed DEMs showed two pronounced peaks at log T % 6:5 and log T % 7:0 K, respectively, similar to brighter solar active regions. A plot of coronal abundances, with respect to stellar photospheric, versus FIP reveals that the FIP behavior of UMa is intermediate between less and more active stars, commensurate with its X-ray luminosity. The abundances of Mg, Fe, and Si are just subsolar, with Fe having the lowest abundance of these. The low-FIP elements Na and Al have similar abundances, and they are both higher than the Mg, Fe, and Si group. The abundances show a minimum at S, rising gradually to Ne, which is higher than photospheric, as has been seen by other authors on similar stars. Some of the FIP behavior seen here is predicted by the new ponderomotive force model of Laming.

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“…研究表明太阳耀斑、太阳风、日冕物质抛射、日冕振荡等很多太阳活动都和日冕磁场存在着密不可分、息息相关的紧密联系 [2,3] . 然而目前探测日冕磁场还存在一定的难度, 这就使得太阳物理学家通过分析冕环的动力学特征来推动对日冕磁场的探究, 进而促进日冕加热 [1,4,5] ;…”

Section: 基于引导滤波和小波变换的太阳冕环结构自动识别算法研究unclassified