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New CubeSat Solar Observations in Soft X-rays (Originally: A Comparison of Flares as Observed in SXR and EUV Spectra)

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Abstract

The Miniature X-ray Solar Spectrometer (MinXSS) CubeSat (Mason et al., 2016) was deployed from the International Space Station on 2016 May 16 and has been taking routine soft x-ray (SXR) measurements of the sun since 2016 June 9. Since that time, >386 flares have occurred (see histogram). Using the methods outlined in Woods, et al. (2016), we can estimate abundance through the mission and compare to the expectations for coronal and photospheric abundances. In particular, we compare abundance during confined versus eruptive flares. The hypothesis is that the chromospheric evaporation common in eruptive flares should result in some photospheric/chromospheric abundance levels appearing in the corona, while confined flares should only show coronal abundances. The analysis presented here confirms this expectation, with the interesting caveat that eruptive active regions tend to show photospheric abundances rather than being restricted to single flare events. We also show how MinXSS data, despite originating from a low-cost CubeSat, can be combined with other high quality solar measurements. In this case, we plot EUV spectral data from SDO/EVE/MEGS-B along with the MinXSS/X123 data.
CubeSat: MinXSS is tiny: 34 cm x10cm x10cm
(think of a loaf of bread) and only 3.5 kg (7.7 lbs).
You’ll still find all the components of bigger satellites
inside, just miniaturized. It’s the first CubeSat launched
for NASA Science Mission Directorate’s new CubeSat
Initiative.
Flare observations:Two MinXSS CubeSats were built.
The first one only has a 3-month comprehensive
success criteria and a ~10 month expected lifetime.It’s
now been running for 7 months and has been very
fortunate to observe lots of flares that are small enough
not to hit the high side of the MinXSS-1/X123’s
dynamic range. It starts to see decent amounts of pile up
in the mid-M range.
Results
We would like to thank the reviewer of our recent ApJ paper that included some of this abundance
analysis for helpful feedback and the Heliophysics Event Knowledgebase for their great services, which
were used extensively to do this analysis.
Dennis, B. R., Phillips, K. J. H., Schwartz, R. A., et al. 2015, ApJ,803, 67
Fludra, A., & Schmelz, J. T. 1999, A&A,348, 286
Mason, J. P., Woods, T. N., Caspi, A., et al. 2016, J. Spacecraft Rockets,53, 328
Moore, C., et al., 2017, in prep
Phillips, K. J. H. 2004, ApJ,605, 921
Schmelz, J. T. 1993, ApJ,408, 373
Sylwester, J., Lemen, J. R., & Mewe, R. 1984, Nature, 310, 665
Warren, H. P. 2014, ApJL,786, L2
Woods, T. N., et al. 2016, ApJ, in press
Method
1. Start with a MinXSS/X123 spectrum:
2. Fit CHIANTI synthetic spectra – two multi-isothermal temperature models to
generate synthetic spectra. Fit a hot component (>10 MK) to X123
measurements. If any residual at low energies, add in cooler component (~few
MK) to synthetic spectrum. (Woods et al. 2016)
3. Derive abundance from abundance-sensitive emission line (Fe XXV 6.7 keV,
Phillips, 2004) - Coronal / photospheric ratio of low-first-ionization potential
(FIP) abundance for reference CHIANTI spectra is 2.138. (Woods et al. 2016)
4. Determine if flares are eruptive or confined – Manual determination for 214
flares in SDO/AIA cutout movies for a variety of EUV wavelengths.
The Miniature X-ray Solar Spectrometer (MinXSS)
CubeSat (Mason et al., 2016) was deployed from the
International Space Station on 2016 May 16 and has
been taking routine soft x-ray (SXR) measurements of
the sun since 2016 June 9. Since that time, >386 flares
have occurred (see histogram). Using the methods
outlined in Woods, et al. (2016), we can estimate
abundance through the mission and compare to the
expectations for coronal and photospheric abundances.
In particular, we compare abundance during confined
versus eruptive flares.The hypothesis is that the
chromospheric evaporation common in eruptive flares
should result in some photospheric/chromospheric
abundance levels appearing in the corona, while
confined flares should only show coronal abundances.
The analysis presented here confirms this expectation,
with the interesting caveat that eruptive active regions
tend to show photospheric abundances rather than being
restricted to single flare events.
We also show how MinXSS data, despite originating
from a low-cost CubeSat, can be combined with other
high quality solar measurements. In this case, we plot
EUV spectral data from SDO/EVE/MEGS-B along with
the MinXSS/X123 data.
MinXSS/X123 data analysis has provided a preliminary indication that eruptive
flares have plasma flow from the chromosphere/photosphere into the corona, but
confined flares (or active regions that only produced confined flares) do not. We
need to perform a more robust abundance calculation that is not so strongly tied
to high temperatures (>6.8 MK). Historically, abundance factors during flares
have been interesting but conflicted: some say coronal abundance, some say
photospheric, some say a mixture (Sylwester et al.,1984; Schmelz, 1993;
Warren, 2014; Fludra & Schmelz, 1999; Dennis et al., 2015). MinXSS data can
be used to test a hypotheses about coronal plasma during flares. Non-flare data
can be used to track active region evolution (Moore, 2017, in prep). MinXSS
data can also be used for joint observations with other established observatories.
SOLAR ABUNDANCE DURING ERUPTIVE VS. CONFINED FLARES
MINXSS AND FRIENDS – JOINT OBSERVATIONS
ABSTRACT
CONCLUSIONS
NEW CUBESAT SOLAR OBSERVATIONS IN SOFT X-RAYS
JAMES PAUL MASON1, THOMAS N. WOODS1, AMIR CASPI2, CHRISTOPHER MOORE1
1LABORATORY FOR ATMOSPHERIC AND SPACE PHYSICS, UNIVERSITY OF COLORADO AT BOULDER, 2SOUTHWEST RESEARCH INSTITUTE
JAMES.MASON@LASP.COLORADO.EDU SH13A-2287
ACKNOWLEDGEMENTS, REFERENCES
Great pairings:
SDO/EVE (EUV spectra)
Hinode XRT (SXR images)
GOES/XRS (SXR broadband)
NuStar (SXR high sensitivity)
MINXSS AND FLARE LUCK
Eruptive example
SDO/AIA 131 Å
2016-07-09 ~15:11
C2.6
Confined example
SDO/AIA 171 Å
2016-06-09 ~12:28
C1.5
Typical eruptive flare: widely varying
abundance
Typical confined flare: only coronal
abundance
Confined flare from eruptive active region
(NAR 12567): widely varying abundance
Eruptive flare from NOAA Active Region
(NAR) 12567: widely varying abundance
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Article
Full-text available
Variations in chemical composition during solar flares have been inferred from elemental abundance changes in cosmic ray fluxes, but have so far not been detected spectroscopically. The first spectroscopic evidence for the variation of the coronal calcium abundance in high-temperature solar flare plasmas is presented. The analyzed data consist of the high-resolution X-ray flare spectra observed with the Bent Crystal Spectrometer on board the Solar Maximum Mission satellite and described in detail by Acton et al. (1980). The observed abundance variation has important consequences for the analysis and interpretation of XUV and X-ray spectra.
  • B R Dennis
  • K J H Phillips
  • R A Schwartz
Dennis, B. R., Phillips, K. J. H., Schwartz, R. A., et al. 2015, ApJ, 803, 67
  • A Fludra
  • J T Schmelz
Fludra, A., & Schmelz, J. T. 1999, A&A, 348, 286
  • J P Mason
  • T N Woods
  • A Caspi
Mason, J. P., Woods, T. N., Caspi, A., et al. 2016, J. Spacecraft Rockets, 53, 328
  • C Moore
Moore, C., et al., 2017, in prep Phillips, K. J. H. 2004, ApJ, 605, 921
  • J T Schmelz
Schmelz, J. T. 1993, ApJ, 408, 373
  • H P Warren
Warren, H. P. 2014, ApJL, 786, L2
  • T N Woods
Woods, T. N., et al. 2016, ApJ, in press