Coronal Heat: Solar Loop Temperatures from
                    <i>TRACE</i>
                    Triple-Filter Data

Schmelz, J. T.; Kashyap, Vinay; Weber, Mark

doi:10.1086/518363

Cited by 18 publications

(13 citation statements)

References 23 publications

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“…The lofty goals mentioned above might appear to be out of reach. These results seem reminiscent of the DEM work described by Schmelz et al (2007) for TRACE. TRACE and AIA have similar spatial resolution, but TRACE has only three coronal filters.…”

Section: Discussionsupporting

confidence: 72%

“…Most of these studies assumed that the plasma was isothermal, but see Aschwanden & Nightingale (2005) for a different case. Schmelz et al (2007) found, however, that even these triple-filter data were insufficient to constrain the loop plasma temperature. They showed this explicitly by constructing DEMs with a Markov Chain Monte Carlo based reconstruction algorithm (Kashyap & Drake 1998).…”

Section: Discussionmentioning

confidence: 98%

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Isothermal and Multithermal Analysis of Coronal Loops Observed With Atmospheric Imaging Assembly. Ii. 211 Å Selected Loops

Schmelz

Worley

Anderson

et al. 2011

ApJ

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An important component of coronal loop analysis involves conflicting results on the cross-field temperature distribution. Are loops isothermal or multithermal? The Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory was designed in part to answer this question. AIA has a series of coronal filters that peak at different temperatures and cover the entire active region temperature range. These properties should make AIA ideal for multithermal analysis, but recent results have shown that the response functions of two of the filters, AIA 94 and 131 Å, are missing a significant number of low-temperature emission lines. Here we analyze coronal loops from several active regions that were chosen in the 211 Å channel of AIA, which has a peak response temperature of log T = 6.3. The differential emission measure (DEM) analysis of the 12 loops in our sample reveals that using data from the 131 Å AIA filter distorts the results, and we have no choice but to do the analysis without these data. The 94 Å data do not appear to be as important, simply because the chosen loops are not visible in this channel. If we eliminate the 131 Å data, however, we find that our DEM analysis is not well constrained on the cool temperature end of six of our loops. The information revealed by our 211 selected loops indicates that additional atomic data are required in order to pin down the cross-field temperature distribution.

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Section: Discussionsupporting

confidence: 72%

Section: Discussionmentioning

confidence: 98%

Isothermal and Multithermal Analysis of Coronal Loops Observed With Atmospheric Imaging Assembly. Ii. 211 Å Selected Loops

Schmelz

Worley

Anderson

et al. 2011

ApJ

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“…In that work the temperature map was derived from the multiwavelength observations by the EIT on SOHO. However, the interpretation of EUV images in terms of temperatures is complicated and not unique (e.g., Schmelz et al 2007;Frazin et al 2005b).…”

Section: Discussionmentioning

confidence: 99%

Validation of Two MHD Models of the Solar Corona with Rotational Tomography

Vásquez

Frazin

Hayashi

et al. 2008

ApJ

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We demonstrate a validation of two 3D MHD models of the corona by comparing density values from solar rotational tomography (SRT) to densities and morphological properties of the two MHD solutions for CR 2029 (2005 April 21YMay 18). The two MHD models are given by the Stanford and Michigan models, and both use the same synoptic magnetogram from MDI as a lower boundary condition. The SRT reconstructions are based on polarized white-light images MLSO Mk IV data for the region between 1.1 and 1.5 R (solar radii) and LASCO C2 for the region between 2.3 and 6.0 R . While the Stanford MHD model reasonably reproduces the tomographic density over the south pole, it fares less well over the north pole, and the Michigan MHD model underestimates the density over both poles. At lower latitudes, we find that while the MHD models have better agreement with the tomographic densities in the region below 3.5 R , at larger heights the agreement is more problematic. Our interpretation is that the base densities and temperatures of the models need to be improved, as well as their radial density gradients.

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“…The effects of plasma multithermality are discussed in Reale et al (2007) and for TRACE in e.g. Weber et al (2005) and Schmelz et al (2007b). We return to the assumption of isothermal plasma in Sect.…”

Section: Temperature Diagnostic Using Cifrmentioning

confidence: 99%

Is it possible to model observed active region coronal emission simultaneously in EUV and X-ray filters?

Dudík

Dzifčáková

Karlický

et al. 2011

A&A

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Aims. We investigate the possibility of modeling the active region coronal emission in the EUV and X-ray filters using one, universal, steady heating function, tied to the properties of the magnetic field. Methods. We employ a simple, static model to compute the temperature and density distributions in the active region corona. The model allows us to explore a wide range of parameters of the heating function. The predicted EUV and X-ray emission in the filters of EIT/SOHO and XRT/Hinode are calculated and compared with observations. Using the combined improved filter-ratio (CIFR) method, a temperature diagnostic is employed to compare the modeled temperature structure of the active region with the temperature structure derived from the observations. Results. The global properties of the observations are most closely matched for heating functions scaling as B 0.7−0.8 0 /L 0.5 0 that depend on the spatially variable heating scale-length. The modeled X-ray emission originates from locations where large heating scale-lengths are found. However, the majority of the loops observed in the 171 and 195 filters can be modeled only by loops with very short heating scale-lengths. These loops are known to be thermally unstable. We are unable to find a model that both matches the observations in all EUV and X-ray filters, and contains only stable loops. As a result, although our model with a steady heating function can explain some of the emission properties of the 171 and 195 loops, it cannot explain their observed lifetimes. Thus, the model does not lead to a self-consistent solution. The performance of the CIFR method is evaluated and we find that the diagnosed temperature can be approximated with a geometric mean of the emission-measure weighted and maximum temperature along the line of sight. Conclusions. We conclude that if one universal heating function exists, it should be at least partially time-dependent.

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Coronal Heat: Solar Loop Temperatures from TRACE Triple-Filter Data

Cited by 18 publications

References 23 publications

Isothermal and Multithermal Analysis of Coronal Loops Observed With Atmospheric Imaging Assembly. Ii. 211 Å Selected Loops

Isothermal and Multithermal Analysis of Coronal Loops Observed With Atmospheric Imaging Assembly. Ii. 211 Å Selected Loops

Validation of Two MHD Models of the Solar Corona with Rotational Tomography

Is it possible to model observed active region coronal emission simultaneously in EUV and X-ray filters?

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