THERMAL DIAGNOSTICS WITH THE ATMOSPHERIC IMAGING ASSEMBLY ON BOARD THE SOLAR DYNAMICS OBSERVATORY: A VALIDATED METHOD FOR DIFFERENTIAL EMISSION MEASURE INVERSIONS

We study the thermal structure and energetics of the point-like extreme ultraviolet (EUV) brightenings within a system of fan loops observed in the active region AR 11520. These brightenings were simultaneously observed on 2012 July 11 by the High-resolution Coronal (Hi-C) imager and the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO). We identified 27 brightenings by automatically determining intensity enhancements in both Hi-C and AIA 193 Å light curves. The energetics of these brightenings were studied using the Differential Emission Measure (DEM) diagnostics. The DEM weighted temperatures of these transients are in the range log T(K) = 6.2−6.6 with radiative energies ≈1024−25 ergs and densities approximately equal to a few times 109 cm−3. To the best of our knowledge, these are the smallest brightenings in EUV ever detected. We used these results to determine the mechanism of energy loss in these brightenings. Our analysis reveals that the dominant mechanism of energy loss for all the identified brightenings is conduction rather than radiation.

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The 3D solar corona Cycle 24 rising phase from SDO/AIA tomography

Proceedings of the International Astronomical Union ◽

10.1017/s1743921312004905 ◽

2011 ◽

Vol 7 (S286) ◽

pp. 238-241

Author(s):

Federico A. Nuevo ◽

Alberto M. Vásquez ◽

Richard A. Frazin ◽

Zhenguang Huang ◽

Ward B. Manchester

Keyword(s):

Solar Corona ◽

Extreme Ultraviolet ◽

Emission Measure ◽

Source Surface ◽

Solar Dynamics Observatory ◽

Differential Emission Measure ◽

Height Range ◽

Field Source ◽

Solar Dynamics ◽

Cycle 24

AbstractWe recently extended the differential emission measure tomography (DEMT) technique to be applied to the six iron bands of the Atmospheric Imaging Assembly (AIA) instrument aboard the Solar Dynamics Observatory (SDO). DEMT products are the 3D reconstruction of the coronal emissivity in the instrument's bands, and the 3D distribution of the local differential emission measure, in the height range 1.0 to 1.25 R⊙. We show here derived maps of the electron density and temperature of the inner solar corona during the rising phase of solar Cycle 24. We discuss the distribution of our results in the context of open/closed magnetic regions, as derived from a global potential field source surface (PFSS) model of the same period. We also compare the results derived with SDO/AIA to those derived with the Extreme UltraViolet Imager (EUVI) instrument aboard the Solar TErrestrial RElations Observatory (STEREO).

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SITES: Solar Iterative Temperature Emission Solver for Differential Emission Measure Inversion of EUV Observations

Solar Physics ◽

10.1007/s11207-019-1525-4 ◽

2019 ◽

Vol 294 (10) ◽

Cited By ~ 4

Author(s):

Huw Morgan ◽

James Pickering

Keyword(s):

Large Scale ◽

Extreme Ultraviolet ◽

Emission Measure ◽

Synthetic Data ◽

Temperature Response ◽

Solar Dynamics Observatory ◽

Differential Emission Measure ◽

Desktop Computer ◽

Temperature Regimes ◽

Solar Dynamics

Abstract Extreme ultraviolet (EUV) images of the optically-thin solar corona in multiple spectral channels give information on the emission as a function of temperature through differential emission measure (DEM) inversions. The aim of this paper is to describe, test, and apply a new DEM method named the Solar Iterative Temperature Emission Solver (SITES). The method creates an initial DEM estimate through a direct redistribution of observed intensities across temperatures according to the temperature response function of the measurement, and iteratively improves on this estimate through calculation of intensity residuals. It is simple in concept and implementation, is non-subjective in the sense that no prior constraints are placed on the solutions other than positivity and smoothness, and can process a thousand DEMs a second on a standard desktop computer. The resulting DEMs replicate model DEMs well in tests on Atmospheric Imaging Assembly/Solar Dynamics Observatory (AIA/SDO) synthetic data. The same tests show that SITES performs less well on very narrow DEM peaks, and should not be used for temperature diagnostics below ${\approx\,}0.5~\mbox{MK}$≈0.5MK in the case of AIA observations. The SITES accuracy of inversion compares well with two other established methods. A simple yet powerful new method to visualize DEM maps is introduced, based on a fractional emission measure (FEM). Applied to a set of AIA full-disk images, the SITES method and FEM visualization show very effectively the dominance of certain temperature regimes in different large-scale coronal structures. The method can easily be adapted for any multi-channel observations of optically-thin plasma and, given its simplicity and efficiency, will facilitate the processing of large existing and future datasets.

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Estimate of Plasma Temperatures Across a CME-Driven Shock from a Comparison Between EUV and Radio Data

Solar Physics ◽

10.1007/s11207-020-01686-0 ◽

2020 ◽

Vol 295 (9) ◽

Author(s):

Federica Frassati ◽

Salvatore Mancuso ◽

Alessandro Bemporad

Keyword(s):

Shock Wave ◽

Compression Ratio ◽

Emission Measure ◽

Type Ii ◽

Solar Dynamics Observatory ◽

Radio Data ◽

Shock Temperature ◽

Post Shock ◽

Dem Analysis ◽

Solar Dynamics

Abstract In this work, we analyze the evolution of an EUV wave front associated with a solar eruption that occurred on 30 October 2014, with the aim of investigating, through differential emission measure (DEM) analysis, the physical properties of the plasma compressed and heated by the accompanying shock wave. The EUV wave was observed by the Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory (SDO) and was accompanied by the detection of a metric Type II burst observed by ground-based radio spectrographs. The EUV signature of the shock wave was also detected in two of the AIA channels centered at 193 Å and 211 Å as an EUV intensity enhancement propagating ahead of the associated CME. The density compression ratio $X$ X of the shock as inferred from the analysis of the EUV data is $X \approx 1.23$ X ≈ 1.23 , in agreement with independent estimates obtained from the analysis of the Type II band-splitting of the radio data and inferred by adopting the upstream–downstream interpretation. By applying the Rankine–Hugoniot jump conditions under the hypothesis of a perpendicular shock, we also estimate the temperature ratio as $T_{\mathrm{D}}/T_{\mathrm{U}} \approx 1.55$ T D / T U ≈ 1.55 and the post-shock temperature as $T_{\mathrm{D}}\approx 2.75$ T D ≈ 2.75 MK. The modest compression ratio and temperature jump derived from the EUV analysis at the shock passage are typical of weak coronal shocks.

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Automated Temperature and Emission Measure Analysis of Coronal Loops and Active Regions Observed with the Atmospheric Imaging Assembly on the Solar Dynamics Observatory (SDO/AIA)

Solar Physics ◽

10.1007/s11207-011-9876-5 ◽

2011 ◽

Vol 283 (1) ◽

pp. 5-30 ◽

Cited By ~ 85

Author(s):

Markus J. Aschwanden ◽

Paul Boerner ◽

Carolus J. Schrijver ◽

Anna Malanushenko

Keyword(s):

Emission Measure ◽

Active Regions ◽

Coronal Loops ◽

Solar Dynamics Observatory ◽

Measure Analysis ◽

Solar Dynamics

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Differential Emission Measure Plasma Diagnostics of a Long-Lived Coronal Hole

Solar Physics ◽

10.1007/s11207-019-1570-z ◽

2020 ◽

Vol 295 (1) ◽

Cited By ~ 3

Author(s):

Jonas Saqri ◽

Astrid M. Veronig ◽

Stephan G. Heinemann ◽

Stefan J. Hofmeister ◽

Manuela Temmer ◽

...

Keyword(s):

Coronal Hole ◽

Scattered Light ◽

Emission Measure ◽

Stray Light ◽

Lunar Eclipse ◽

Solar Dynamics Observatory ◽

Differential Emission Measure ◽

Plasma Properties ◽

Evolutionary Pattern ◽

Dominant Component

AbstractWe use Solar Dynamics Observatory (SDO)/Atmospheric Imaging Assembly (AIA) data to reconstruct the plasma properties from differential emission measure (DEM) analysis for a previously studied long-lived, low-latitude coronal hole (CH) over its lifetime of ten solar rotations. We initially obtain a non-isothermal DEM distribution with a dominant component centered around 0.9 MK and a secondary smaller component at 1.5 – 2.0 MK. We find that deconvolving the data with the instrument point spread function (PSF) to account for long-range scattered light reduces the secondary hot component. Using the 2012 Venus transit and a 2013 lunar eclipse to test the efficiency of this deconvolution, significant amounts of residual stray light are found for the occulted areas. Accounting for this stray light in the error budget of the different AIA filters further reduces the secondary hot emission, yielding CH DEM distributions that are close to isothermal with the main contribution centered around 0.9 MK. Based on these DEMs, we analyze the evolution of the emission measure (EM), density, and averaged temperature during the CH’s lifetime. We find that once the CH is clearly observed in EUV images, the bulk of the CH plasma reveals a quite constant state, i.e. temperature and density reveal no major changes, whereas the total CH area and the photospheric magnetic fine structure inside the CH show a distinct evolutionary pattern. These findings suggest that CH plasma properties are mostly “set” at the CH formation or/and that all CHs have similar plasma properties.

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A deep learning virtual instrument for monitoring extreme UV solar spectral irradiance

Science Advances ◽

10.1126/sciadv.aaw6548 ◽

2019 ◽

Vol 5 (10) ◽

pp. eaaw6548

Author(s):

Alexandre Szenicer ◽

David F. Fouhey ◽

Andres Munoz-Jaramillo ◽

Paul J. Wright ◽

Rajat Thomas ◽

...

Keyword(s):

Virtual Instrument ◽

Extreme Ultraviolet ◽

Aerodynamic Drag ◽

Emission Measure ◽

Maximum Error ◽

Spectral Irradiance ◽

Solar Dynamics Observatory ◽

Solar Spectral Irradiance ◽

Solar Dynamics ◽

Using Data

Measurements of the extreme ultraviolet (EUV) solar spectral irradiance (SSI) are essential for understanding drivers of space weather effects, such as radio blackouts, and aerodynamic drag on satellites during periods of enhanced solar activity. In this paper, we show how to learn a mapping from EUV narrowband images to spectral irradiance measurements using data from NASA’s Solar Dynamics Observatory obtained between 2010 to 2014. We describe a protocol and baselines for measuring the performance of models. Our best performing machine learning (ML) model based on convolutional neural networks (CNNs) outperforms other ML models, and a differential emission measure (DEM) based approach, yielding average relative errors of under 4.6% (maximum error over emission lines) and more typically 1.6% (median). We also provide evidence that the proposed method is solving this mapping in a way that makes physical sense and by paying attention to magnetic structures known to drive EUV SSI variability.

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Estimation of Plasma Properties and Magnetic Field in a Prominence-like Structure as Observed by SDO/AIA

Proceedings of the International Astronomical Union ◽

10.1017/s1743921313011290 ◽

2013 ◽

Vol 8 (S300) ◽

pp. 405-407

Author(s):

B. N. Dwivedi ◽

A. K. Srivastava ◽

Anita Mohan

Keyword(s):

Magnetic Field ◽

Flux Tube ◽

Emission Measure ◽

Solar Dynamics Observatory ◽

Plasma Parameters ◽

Plasma Properties ◽

Plasma Dynamics ◽

Cool Plasma ◽

Kink Waves ◽

Solar Dynamics

AbstractWe analyze a prominence-like cool plasma structure as observed by Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory (SDO). We perform the Differential Emission Measure (DEM) analysis using various filters of AIA, and also deduce the temperature and density structure in and around the observed flux-tube. In addition to deducing plasma parameters, we also find an evidence of multiple harmonics of fast magnetoacoustic kink waves in the observed prominence-like magnetic structure. Making use of estimated plasma parameters and observed wave parameters, under the baseline of MHD seismology, we deduce magnetic field in the flux-tube. The wave period ratio P1/P2 = 2.18 is also observed in the flux-tube, which carries the signature of magnetic field divergence where we estimate the tube expansion factor as 1.27. We discuss constraints in the estimation of plasma and magnetic field properties in such a structure in the current observational perspective, which may shed new light on the localized plasma dynamics and heating scenario in the solar atmosphere.

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The EUV spectrum of the Sun: Quiet- and active-Sun irradiances and chemical composition

Astronomy and Astrophysics ◽

10.1051/0004-6361/201834842 ◽

2019 ◽

Vol 624 ◽

pp. A36 ◽

Cited By ~ 5

Author(s):

G. Del Zanna

Keyword(s):

Excellent Agreement ◽

Extreme Ultraviolet ◽

Emission Measure ◽

Active Regions ◽

Atomic Data ◽

Solar Dynamics Observatory ◽

Chemical Abundances ◽

Temperature Plasma ◽

Medium Resolution ◽

Solar Dynamics

We benchmark new atomic data against a selection of irradiances obtained from medium-resolution quiet-Sun spectra in the extreme ultraviolet (EUV), from 60 to 1040 Å. We used as a baseline the irradiances measured during solar minimum on 2008 April 14 by the prototype (PEVE) of the Solar Dynamics Observatory Extreme ultraviolet Variability Experiment (EVE). We took into account some inconsistencies in the PEVE data, using flight EVE data and irradiances we obtained from Solar and Heliospheric Observatory (SoHO) Coronal Diagnostics Spectrometer (CDS) data. We performed a differential emission measure and find overall excellent agreement (to within the accuracy of the observations, about 20%) between predicted and measured irradiances in most cases, although we point out several problems with the currently available ion charge-state distributions. We used the photospheric chemical abundances of Asplund et al. (2009, ARA&A, 47, 481). The new atomic data are nearly complete in this spectral range for medium-resolution irradiance spectra. Finally, we used observations of the active Sun in 1969 to show that the composition of the solar corona up to 1 MK is nearly photospheric in this case as well. Variations of a factor of 2 are present for higher-temperature plasma, which is emitted within active regions. These results are in excellent agreement with our previous findings.

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Temperature of Source Regions of 3He-Rich Impulsive Solar Energetic Particle Events

Proceedings of the International Astronomical Union ◽

10.1017/s1743921317007980 ◽

2017 ◽

Vol 13 (S335) ◽

pp. 14-16 ◽

Cited By ~ 1

Author(s):

N.-H. Chen ◽

R. Bučík ◽

R.-S. Kim

Keyword(s):

Energetic Particle ◽

Emission Measure ◽

Solar Energetic Particle ◽

Heavy Ion ◽

Solar Dynamics Observatory ◽

Dissipation Process ◽

Solar Source ◽

Source Regions ◽

Dem Analysis ◽

Solar Dynamics

AbstractImpulsive solar energetic particle (SEP) events originate from the energy dissipation process in small solar flares. Anomalous abundances in impulsive SEP events provide an evidence on unique, yet unclear, acceleration mechanism. The pattern of heavy-ion enhancements indicates that the temperature of the source plasma that is accelerated is low and not flare-like. We examine the solar source of the 3He-rich SEP event of 2012 November 20 using Solar Dynamics Observatory (SDO)/ Atmospheric Imaging Assembly (AIA) images and investigate its thermal variation. The examined event is associated with recurrent coronal jets. The Differential Emission Measure (DEM) analysis is applied to study the temperature evolution/distribution of the source regions. Preliminary results show that the temperature of the associated solar source is ranged between 1.2-3.1 MK.

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