Predicting the corona for the 21 August 2017 total solar eclipse

Mikić, Z.; Downs, Cooper; Linker, J. A.; Caplan, Ronald M.; Mackay, D. H.; Upton, Lisa; Riley, Pete; Lionello, R.; Török, Tibor; Titov, V. S.; Wijaya, Janvier; Druckmüller, Miloslav; Pasachoff, Jay M.; Carlos, Wendy

doi:10.1038/s41550-018-0562-5

Cited by 131 publications

(151 citation statements)

References 100 publications

(129 reference statements)

Supporting

Mentioning

137

Contrasting

Order By: Relevance

“…3.1 and 3.2 show that the WTD model described in Sec. 2 cannot reproduce the charge states of ions in the solar wind, we have looked for possible improvements that may also be implemented in the 3D model of Mikić et al (2018). One possible reason why the charge states in our model are too low is that we do not include the effect of a suprathermal electron tail in the corona that would increase the ionization coefficients (Ko et al, 1996;Esser, Edgar, and Brickhouse, 1998;Cranmer, 2014).…”

Section: Correcting the Ion Outflow Speedmentioning

confidence: 99%

“…Oran et al (2015) pioneered in this effort by using an external code to evaluate charge states in the solar wind calculation obtained with the Alfvén Wave Solar Model (AWSoM), and comparing them with in situ measurements from Ulysses. Recently we incorporated a Wave-Turbulence-Driven (WTD) formulation for coronal heating and solar wind acceleration by Alfvénic turbulence into a 3D MHD model of the global solar corona (Mikić et al, 2018). In this effort, we constrained the model by forward modeling EUV, X-Ray, and white-light coronal emission and comparing directly to observations.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Ion Charge States in a Time-Dependent Wave-Turbulence-Driven Model of the Solar Wind

et al. 2019

Self Cite

View full text Add to dashboard Cite

Ion fractional charge states, measured in situ in the heliosphere, depend on the properties of the plasma in the inner corona. As the ions travel outward in the solar wind and the electron density drops, the charge states remain essentially unaltered or "frozen in". Thus they can provide a powerful constraint on heating models of the corona and acceleration of the solar wind. We have implemented non-equilibrium ionization calculations into a 1D wave-turbulence-driven (WTD) hydrodynamic solar wind model and compared modeled charge states with the Ulysses 1994-5 in situ measurements. We have found that modeled charge state ratios of C 6+ /C 5+ and O 7+ /O 6+ , among others, were too low compared with Ulysses measurements. However, a heuristic reduction of the plasma flow speed has been able to bring the modeled results in line with observations, though other ideas have been proposed to address this discrepancy. We discuss implications of our results and the prospect of including ion charge state calculations into our 3D MHD model of the inner heliosphere.

show abstract

Section: Correcting the Ion Outflow Speedmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Ion Charge States in a Time-Dependent Wave-Turbulence-Driven Model of the Solar Wind

et al. 2019

Self Cite

View full text Add to dashboard Cite

show abstract

“…Since we are dealing with a corona close to the minimum of solar activity, two main parts around the Sun are prominent: first, equatorial regions with big loops and arches of the extended streamers, and second, the polar regions with coronal holes (see Fig. 3 and Mikić et al 2018, dealing with the modeling of coronal structures). Intermediate regions can also be discussed, such as the eastern active region and the edges of streamers or edges of CHs.…”

Section: The K and F Spectramentioning

confidence: 99%

New deep coronal spectra from the 2017 total solar eclipse

Koutchmy

Baudin

Abdi

et al. 2019

A&A

View full text Add to dashboard Cite

Context. The origin of the high temperature of the solar corona, in both the inner bright parts and the more outer parts showing flows toward the solar wind, is not understood well yet. Total eclipses permit a deep analysis of both the inner and the outer parts of the corona using the continuum white-light (W-L) radiations from electrons (K-corona), the superposed spectrum of forbidden emission lines from ions (E-corona), and the dust component with F-lines (F-corona). Aims. By sufficiently dispersing the W-L spectrum, the Fraunhofer (F) spectrum of the dust component of the corona appears and the continuum Thomson radiation can be evaluated. The superposed emission lines of ions with different degrees of ionization are studied to allow the measurement of temperatures, non-thermal velocities, Doppler shifts, and abundances to constrain the proposed heating mechanisms and understand the origin of flows that lead to solar wind. Methods. We describe a slit spectroscopic experiment of high spectral resolution to provide an analysis of the most typical parts of the quasi-minimum type corona observed during the total solar eclipse of Aug 21, 2017 from Idaho, USA. Streamers, active region enhancements, and polar coronal holes (CHs) are measured well using deep spectra. Results. Sixty spectra are obtained during the totality with a long slit, covering ±3 solar radii in the range of 510 nm to 590 nm. The K+F continuum corona is exposed well up to two solar radii. The F-corona can be measured even at the solar limb. New weak emission lines were discovered or confirmed. The rarely observed Ar X line is detected almost everywhere; the Fe XIV and Ni XIII lines are clearly detected everywhere. For the first time hot lines are also measured inside the CH regions. The radial variations of the non-thermal turbulent velocities of the lines do not show a great departure from the average values. No significantly large Doppler shifts are seen anywhere in the inner or the middle corona. The wings of the Fe XIV line show some non-Gaussianity. Conclusions. Deep slit coronal spectra offered an opportunity for diagnosing several aspects of coronal physics during a well observed total eclipse without extended investments. The analysis of the ionic emission line profiles offers several powerful diagnostics of the coronal dynamics; the precise measurement of the F-continuum component provides insight into the ubiquitous dust corona at the solar limb.1

show abstract

“…Mikić et al 1999;Lionello et al 2009;Downs et al 2013;Caplan et al 2017), which was used to predict the structure of the global corona during the 21 August 2017 total solar eclipse. Described in detail by Mikić et al (2018), this calculation employed high-fidelity magnetic field observations at the inner boundary, a new Wave-Turbulence-Driven (WTD) coronal heating model (Downs et al 2016), and a method to energize large-scale magnetic flux-systems in the low corona. Forward modeled observables, including SDO/AIA EUV images, temperature maps from DEM inversions, and broadband visible light images, compared favorably with observations, making this an ideal model to use here.…”

Section: Description Of the Modelmentioning

confidence: 99%

Unfolding Overlapped Slitless Imaging Spectrometer Data for Extended Sources

Winebarger

Weber

Bethge

et al. 2019

ApJ

Self Cite

View full text Add to dashboard Cite

Slitless spectrometers can provide simultaneous imaging and spectral data over an extended field of view, thereby allowing rapid data acquisition for extended sources. In some instances, when the object is greatly extended or the spectral dispersion is too small, there may be locations in the focal plane where emission lines at different wavelengths contribute. It is then desirable to unfold the overlapped regions in order to isolate the contributions from the individual wavelengths. In this paper, we describe a method for such an unfolding, using an inversion technique developed for an extreme ultraviolet imaging spectrometer and coronagraph named the COronal Spectroscopic Imager in the EUV (COSIE). The COSIE spectrometer wavelength range (18.6 -20.5 nm) contains a number of strong coronal emission lines and several density sensitive lines. We focus on optimizing the unfolding process to retrieve emission measure maps at constant temperature, maps of spectrally pure intensity in the Fe XII and Fe XIII lines and density maps based on both Fe XII and Fe XIII diagnostics.

show abstract

Predicting the corona for the 21 August 2017 total solar eclipse

Cited by 131 publications

References 100 publications

Ion Charge States in a Time-Dependent Wave-Turbulence-Driven Model of the Solar Wind

Ion Charge States in a Time-Dependent Wave-Turbulence-Driven Model of the Solar Wind

New deep coronal spectra from the 2017 total solar eclipse

Unfolding Overlapped Slitless Imaging Spectrometer Data for Extended Sources

Contact Info

Product

Resources

About