WARM AND FUZZY: TEMPERATURE AND DENSITY ANALYSIS OF AN Fe XV EUV IMAGING SPECTROMETER LOOP

Schmelz, J. T.; Rightmire, Lisa; Saar, Steven H.; Kimble, J. A.; Worley, B. T.; Pathak, S.

doi:10.1088/0004-637x/738/2/146

Cited by 20 publications

(14 citation statements)

References 28 publications

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“…[39]. Later results from EIS, which has better spatial and temporal resolution than CDS, were able to confirm the earlier results [40][41][42][43]. Finally, it was demonstrated that the flat temperature distributions described in §2 could be explained using the broad DEM distributions required to explain the CDS spectral line observations [44,45].…”

Section: Multi-thermalsupporting

confidence: 52%

What can observations tell us about coronal heating?

Schmelz

Winebarger

2015

Phil. Trans. R. Soc. A.

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The actual source of coronal heating is one of the longest standing unsolved mysteries in all of astrophysics, but it is only in recent years that observations have begun making significant contributions. Coronal loops, their structure and sub-structure, their temperature and density details, and their evolution with time, may hold the key to solving this mystery. Because spatial resolution of current observatories cannot resolve fundamental scale lengths, information about the heating of the corona must be inferred from indirect observations. Loops with unexpectedly high densities and multi-thermal cross-field temperatures were not consistent with results expected from steady uniform heating models. The hot ( T >5 MK) plasma component of loops may also be a key observation; a new sounding rocket instrument called the Marshall Grazing Incidence X-ray Spectrometer will specifically target this observable. Finally, a loop is likely to be a tangle of magnetic strands. The High Resolution Coronal Imager observed magnetic braids untwisting and reconnecting, dispersing enough energy to heat the surrounding plasma. The existence of multi-thermal, cooling loops and hot plasma provides observational constraints that all viable coronal heating models will need to explain.

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Section: Multi-thermalsupporting

confidence: 52%

What can observations tell us about coronal heating?

Schmelz

Winebarger

2015

Phil. Trans. R. Soc. A.

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“…Since the plasma is prohibited from moving across magnetic field lines, the energy released by magnetic reconnection is difficult to transfer into the CME LF. Therefore, during the magnetic reconnection, the CME flux rope is heated but the LF remains about the same temperature as the quiet coronal loops (e.g., T ∼ 1.0-3.0 MK; Schmelz et al 2010Schmelz et al , 2011aSchmelz et al , 2011b.…”

Section: Discussionmentioning

confidence: 99%

Differential Emission Measure Analysis of Multiple Structural Components of Coronal Mass Ejections in the Inner Corona

Cheng

Zhang

Saar

et al. 2012

ApJ

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In this paper, we study the temperature and density properties of multiple structural components of coronal mass ejections (CMEs) using differential emission measure (DEM) analysis. The DEM analysis is based on the sixpassband EUV observations of solar corona from the Atmospheric Imaging Assembly on board the Solar Dynamic Observatory. The structural components studied include the hot channel in the core region (presumably the magnetic flux rope of the CME), the bright loop-like leading front (LF), and coronal dimming in the wake of the CME. We find that the presumed flux rope has the highest average temperature (>8 MK) and density (∼1.0 × 10 9 cm −3 ), resulting in an enhanced emission measure over a broad temperature range (3 T(MK) 20). On the other hand, the CME LF has a relatively cool temperature (∼2 MK) and a narrow temperature distribution similar to the pre-eruption coronal temperature (1 T(MK) 3). The density in the LF, however, is increased by 2%-32% compared with that of the pre-eruption corona, depending on the event and location. In coronal dimmings, the temperature is more broadly distributed (1 T(MK) 4), but the density decreases by ∼35%-∼40%. These observational results show that: (1) CME core regions are significantly heated, presumably through magnetic reconnection; (2) CME LFs are a consequence of compression of ambient plasma caused by the expansion of the CME core region; and (3) the dimmings are largely caused by the plasma rarefaction associated with the eruption.

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“…They have the same spatial resolution and cover different but overlapping coronal temperature ranges. These properties make a combined data set ideal for multithermal analysis, where the EIS iron lines provide the best information on the cooler corona (log T < 6.5) and the XRT iron-dominated filters provide the best information on the hotter corona (log T > 6.5); see, e.g., Schmelz et al (2010Schmelz et al ( , 2011b and Winebarger et al (2011). Table 2 lists the EIS ions, the wavelengths in angstroms, and the log of the peak formation temperatures of the spectral lines used in this analysis.…”

Section: Discussionmentioning

confidence: 99%

“….12 density-sensitive pair. We then refined this estimate using the DEM-weighted density technique described by Schmelz et al (2011b); these values are listed in Table 1. We used this density, the EIS Fe ix-Fe xvi lines, and the XRT filter(s) to produce an EMD curve for each active region core area.…”

Section: The Intensity For Each Spectral Line Observed By Eis Is Propmentioning

confidence: 99%

The Cold Shoulder: Emission Measure Distributions of Active Region Cores

Schmelz

Pathak

2012

ApJ

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The coronal heating mechanism for active region core loops is difficult to determine because these loops are often not resolved and cannot be studied individually. Rather, we concentrate on the "inter-moss" areas between loop footpoints. We use observations from the Hinode EUV Imaging Spectrometer and the X-Ray Telescope to calculate the emission measure distributions of eight inter-moss areas in five different active regions. The combined data sets provide both high-and low-temperature constraints and ensure complete coverage in the temperature range appropriate for active regions. For AR 11113, the emission can be modeled with heating events that occur on timescales less than the cooling time. The loops in the core regions appear to be close to equilibrium and are consistent with steady heating. The other regions studied, however, appear to be dominated by nanoflare heating. Our results are consistent with the idea that active region age is an important parameter in determining whether steady or nanoflare heating is primarily responsible for the core emission, that is, older regions are more likely to be dominated by steady heating, while younger regions show more evidence of nanoflares.

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WARM AND FUZZY: TEMPERATURE AND DENSITY ANALYSIS OF AN Fe XV EUV IMAGING SPECTROMETER LOOP

Cited by 20 publications

References 28 publications

What can observations tell us about coronal heating?

What can observations tell us about coronal heating?

Differential Emission Measure Analysis of Multiple Structural Components of Coronal Mass Ejections in the Inner Corona

The Cold Shoulder: Emission Measure Distributions of Active Region Cores

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