Benchmark Test of Differential Emission Measure Codes and Multi-thermal Energies in Solar Active Regions

Aschwanden, Markus J.; Boerner, P.; Caspi, Amir; McTiernan, J.; Ryan, Daniel; Warren, H. P.

doi:10.1007/s11207-015-0790-0

Cited by 42 publications

(30 citation statements)

References 55 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Caspi et al 2014Caspi et al , 2015Ryan et al 2014). (4) A suitably accurate DEM method is the spatial synthesis method (Aschwanden 2013;Aschwanden et al 2015a), which fits a Gaussian DEM in each spatial (macro)pixel of AIA images in all coronal wavelengths and synthesizes the DEM distribution by summing the partial DEMs over all (macro)pixels. (5) The flare volume can be estimated from the geometric relationship » V A 3 2 , where the flare area A is measured above some suitable threshold in the emission measure per (macro)pixel (assuming a filling factor of unity for subpixel features).…”

Section: Thermal Energiesmentioning

confidence: 99%

Global Energetics of Solar Flares. V. Energy Closure in Flares and Coronal Mass Ejections

Aschwanden

Caspi

Cohen

et al. 2017

ApJ

Self Cite

138

View full text Add to dashboard Cite

In this study we synthesize the results of four previous studies on the global energetics of solar flares and associated coronal mass ejections (CMEs), which include magnetic, thermal, nonthermal, and CME energies in 399 solar Mand X-class flare events observed during the first 3.5 yr of the Solar Dynamics Observatory (SDO) mission. Our findings are as follows. (1) The sum of the mean nonthermal energy of flare-accelerated particles (E nt ), the energy of direct heating (E dir ), and the energy in CMEs (E CME ), which are the primary energy dissipation processes in a flare, is found to have a ratio of ( ), compared with the dissipated magnetic free energy E mag , which confirms energy closure within the measurement uncertainties and corroborates the magnetic origin of flares and CMEs. (2) The energy partition of the dissipated magnetic free energy is: 0.51±0.17 in nonthermal energy of 6 keV electrons, 0.17±0.17 in nonthermal 1 MeV ions, 0.07±0.14 in CMEs, and 0.07±0.17 in direct heating. (3) The thermal energy is almost always less than the nonthermal energy, which is consistent with the thick-target model. (4) The bolometric luminosity in white-light flares is comparable to the thermal energy in soft X-rays (SXR). (5) Solar energetic particle events carry a fraction »0.03 of the CME energy, which is consistent with CME-driven shock acceleration. (6) The warm-target model predicts a lower limit of the low-energy cutoff at » e 6 keV c , based on the mean peak temperature of the differential emission measure of T e =8.6 MK during flares. This work represents the first statistical study that establishes energy closure in solar flare/CME events.

show abstract

Section: Thermal Energiesmentioning

confidence: 99%

Global Energetics of Solar Flares. V. Energy Closure in Flares and Coronal Mass Ejections

Aschwanden

Caspi

Cohen

et al. 2017

ApJ

Self Cite

138

View full text Add to dashboard Cite

show abstract

“…Additionally, the EIS calibration corrections introduce different wavelength dependences that can also affect the resulting DEMs. Finally, even if we apply the same inversion method to the data (Hannah & Kontar 2012), a narrowband instrument with few channels like AIA is expected to produce a more rough DEM (especially in the higher temperatures where the response function coverage is not dense, Aschwanden et al 2015) in comparison to the DEM produced using EIS. The latter uses many spectral lines and is therefore more sensitive to the details of the plasma thermal distribution.…”

Section: East Regionmentioning

confidence: 99%

The spectroscopic imprint of the pre-eruptive configuration resulting into two major coronal mass ejections

Syntelis

Gontikakis

Patsourakos

et al. 2016

A&A

View full text Add to dashboard Cite

Aims. We present a spectroscopic analysis of the pre-eruptive configuration of active region NOAA 11429, prior to two very fast coronal mass ejections (CMEs) on March 7, 2012 that are associated with this active region. We study the thermal components and the dynamics associated with the ejected flux ropes. Methods. Using differential emission measure (DEM) analysis of Hinode/EIS and SDO/AIA observations, we identify the emission components of both the flux rope and the host active region. We then follow the time evolution of the flux rope emission components by using AIA observations. The plasma density and the Doppler and non-thermal velocities associated with the flux ropes are also calculated from the EIS data. Results. The eastern and western parts of the active region, in which the two different fast CMEs originated during two X-class flares, were studied separately. In both regions we identified an emission component in the temperature range of log T = 6.8−7.1 associated with the presence of flux ropes. The time evolution of the eastern region showed an increase in the mean DEM in this temperature range by an order of magnitude, 5 h prior to the first CME. This was associated with a gradual rise and heating of the flux rope as manifested by blue-shifts and increased non-thermal velocities in Ca xv 200.97 Å, respectively. An overall upward motion of the flux ropes was measured (relative blue-shifts of ∼12 km s −1 ). The measured electron density was found to be 4 × 10 9 −2 × 10 10 cm −3 (using the ratio of Ca xv 181.90 Å over Ca xv 200.97 Å). We compare our findings with other works on the same AR to provide a unified picture of its evolution.

show abstract

“…The shift of the emitting material toward lower temperature below 10 6 K is also roughly consistent with Figure 6. However, see Aschwanden et al (2015) about the uncertainties in DEM inversions. Figure 9 shows the temporal evolution of the "effective temperature" (T eff ) calculated from the EM:…”

Section: Coronal Propertiesmentioning

confidence: 99%

Correlation of Coronal Plasma Properties and Solar Magnetic Field in a Decaying Active Region

Young

Muglach

et al. 2016

ApJ

View full text Add to dashboard Cite

We present the analysis of a decaying active region observed by the EUV Imaging Spectrometer on Hinode during 2009 December 7-11. We investigated the temporal evolution of its structure exhibited by plasma at temperatures from 300,000 to 2.8 million degrees, and derived the electron density, differential emission measure, effective electron temperature, and elemental abundance ratios of Si/S and Fe/S (as a measure of the First Ionization Potential (FIP) Effect). We compared these coronal properties to the temporal evolution of the photospheric magnetic field strength obtained from the Solar and Heliospheric Observatory Michelson Doppler Imager magnetograms. We find that, while these coronal properties all decreased with time during this decay phase, the largest change was at plasma above 1.5 million degrees. The photospheric magnetic field strength also decreased with time but mainly for field strengths lower than about 70 Gauss. The effective electron temperature and the FIP bias seem to reach a "basal" state (at 1.5 × 10 6 K and 1.5, respectively) into the quiet Sun when the mean photospheric magnetic field (excluding all areas <10 G) weakened to below 35 G, while the electron density continued to decrease with the weakening field. These physical properties are all positively correlated with each other and the correlation is the strongest in the high-temperature plasma. Such correlation properties should be considered in the quest for our understanding of how the corona is heated. The variations in the elemental abundance should especially be considered together with the electron temperature and density.

show abstract

Benchmark Test of Differential Emission Measure Codes and Multi-thermal Energies in Solar Active Regions

Cited by 42 publications

References 55 publications

Global Energetics of Solar Flares. V. Energy Closure in Flares and Coronal Mass Ejections

Global Energetics of Solar Flares. V. Energy Closure in Flares and Coronal Mass Ejections

The spectroscopic imprint of the pre-eruptive configuration resulting into two major coronal mass ejections

Correlation of Coronal Plasma Properties and Solar Magnetic Field in a Decaying Active Region

Contact Info

Product

Resources

About