MinXSS and RHESSI measure flare spectra over 1-15 keV
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m (→Introduction: Minor editorial changes. Added the number of RHESSI flares) |
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Figure 1 (from Ref. [1]) demonstrates the MinXSS-RHESSI cohesion with observations | Figure 1 (from Ref. [1]) demonstrates the MinXSS-RHESSI cohesion with observations | ||
| - | of [http://www.swpc.noaa.gov/products/goes-x-ray-flux GOES] | + | of two [http://www.swpc.noaa.gov/products/goes-x-ray-flux GOES] M-class flares - |
| - | + | the M1.2 flare, SOL2016-07-21, and the M5.0 flare, SOL2016-07-23. | |
| - | + | It shows the combined MinXSS spectrum measured between 1 and 7 keV with the overlapping | |
| - | RHESSI | + | RHESSI spectrum from 6 to 15 keV for the M1.2 flare, and a similar |
| - | overlay of MinXSS | + | overlay of the MinXSS spectrum from 1 to 9 keV with the RHESSI |
| - | + | spectrum from 6 to 20 keV for the M5.0 flare. | |
[[Image:316f1.png|500px|thumb|center| | [[Image:316f1.png|500px|thumb|center| | ||
Figure 1: | Figure 1: | ||
MinXSS-1 M1.2 and M5.0 flare photon flux spectra with overlaid | MinXSS-1 M1.2 and M5.0 flare photon flux spectra with overlaid | ||
| - | RHESSI spectra (Ref. [1]). | + | RHESSI spectra (Ref. [1]).]] |
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| - | ]] | + | |
| - | Note the presence of spectral line features in the low-energy (MinXSS) | + | The near-simultaneous measurements shown in Figure 1 provide complete |
| + | spectral coverage from 1 keV to the minimum detected flux from | ||
| + | RHESSI and spans eight orders of magnitude in photon flux. The main overlap | ||
| + | between the two instruments for flares is near the most prominent peak at 6.7 keV from the complex of lines from highly ionized iron near that energy. Note the presence of other significant spectral line features in the low-energy (MinXSS) | ||
spectral range. | spectral range. | ||
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| + | This comparison of X-ray spectra for two solar flares measured simultaneously | ||
| + | with both RHESSI and MinXSS-1 helps validate the MinXSS observations. | ||
=== Conclusions === | === Conclusions === | ||
Revision as of 23:21, 5 February 2018
| Nugget | |
|---|---|
| Number: | 316 |
| 1st Author: | Chris Moore |
| 2nd Author: | Brian Dennis and MinXSS |
| Published: | 5 February 2018 |
| Next Nugget: | Non-Maxwellian Diagnostics from SDO/EVE Spectra of an X-class Flare |
| Previous Nugget: | Parameterized Flare Models with Chromospheric Compressions |
| List all | |
Contents |
Introduction
RHESSI has been performing high-quality X-ray and gamma-ray solar measurements from 3 keV - 17 MeV with a best energy resolution of order 1 keV FWHM over the range from 3 to >100 keV. It has measured well over 100,000 solar flares since its launch in 2002, and has proven to be a reliable NASA Small Explorer Mission (SMEX). But to achieve this wide spectral range - including hard-to-detect gamma rays - RHESSI had to compromise in some ways. In particular, there are systematic response limitations below about 6 keV. The Miniature X-ray Solar Spectrometer (MinXSS) CubeSat (ref. [2]) is designed to thrive in this spectral region. MinXSS thus nicely complements RHESSI's observations of solar flares with high-resolution spectral coverage from ~1 to >15 keV.
Joint observations of solar flares
Figure 1 (from Ref. [1]) demonstrates the MinXSS-RHESSI cohesion with observations of two GOES M-class flares - the M1.2 flare, SOL2016-07-21, and the M5.0 flare, SOL2016-07-23. It shows the combined MinXSS spectrum measured between 1 and 7 keV with the overlapping RHESSI spectrum from 6 to 15 keV for the M1.2 flare, and a similar overlay of the MinXSS spectrum from 1 to 9 keV with the RHESSI spectrum from 6 to 20 keV for the M5.0 flare.
The near-simultaneous measurements shown in Figure 1 provide complete spectral coverage from 1 keV to the minimum detected flux from RHESSI and spans eight orders of magnitude in photon flux. The main overlap between the two instruments for flares is near the most prominent peak at 6.7 keV from the complex of lines from highly ionized iron near that energy. Note the presence of other significant spectral line features in the low-energy (MinXSS) spectral range.
This comparison of X-ray spectra for two solar flares measured simultaneously with both RHESSI and MinXSS-1 helps validate the MinXSS observations.
Conclusions
The combined measurements of MinXSS and RHESSI open new parameter space and context to understanding solar flare processes, evolution and abundance variations. The effective spectral resolution of the MinXSS-1 X-ray spectrometer (X123) is roughly 0.240 keV across the whole 0.8-12 keV bandpass which allows for the improved access to emission-line diagnostics. The consistency in the spectral shape between the RHESSI and MinXSS simultaneous observations affirms the quality of the MinXSS data. Cross-calibration between the two will be conducted in the near future to quantify and understand the subtle differences in the spectra. MinXSS spectra can be used to infer flare plasma temperature, emission measure, thermal energy, elemental abundance variations during the flare (see one of the MinXSS Nuggets for a discussion of elemental abundances. RHESSI spectra provide flare spatial information, non-thermal accelerated electron energy flux, thermal energy, plasma temperature and emission measure. Future temporal analysis following the electron beam target model, can map the non-thermal accelerated electron distribution during early phases of the flare (deduced by RHESSI) to the thermal evolution and abundance variations in the later phases of the flare (inferred by MinXSS and RHESSI).
References
[1] "The Reuven Ramaty High-Energy Solar Spectroscopic Imager (RHESSI)"
[2] "The Instruments and Capabilities of the Miniature X-ray Solar Spectrometer (MinXSS) CubeSats"
| RHESSI Nugget Date | 5 February 2018 + |
| RHESSI Nugget First Author | Chris Moore + |
| RHESSI Nugget Index | 316 + |
| RHESSI Nugget Second Author | Brian Dennis and MinXSS + |
