A Solar cycle correlation of coronal element abundances in Sun-as-a-star observations

Brooks, David H.; Baker, D.; Driel‐Gesztelyi, L. van; Warren, Harry P.

doi:10.1038/s41467-017-00328-7

Cited by 38 publications

(62 citation statements)

References 50 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Note that Brooks et al (2017) found a strong correlation between FIP-bias, measured from low-and high-FIP elements, and F10.7 cm flux, but the anti-correlation we find between the A(Ne)/A(O) ratios and the 27 day running averaged F10.7 cm flux is slightly weaker during this period. This suggests that the correlation found by Brooks et al (2017) is driven by the behavior of the low-FIP elements with the solar cycle.…”

Section: Neon/oxygen Abundancesmentioning

confidence: 60%

“…Furthermore, the post-revision of Asplund et al (2009) was inferred from EUV spectroscopic measurements of the solar transition region between the photosphere and corona by Young (2005), where no elemental fractionation is observed. Note, however, that very recent measurements by Brooks et al (2017) show evidence of fractionation even at temperatures associated with the upper transition region (∼0.5 MK).…”

Section: Introductionmentioning

confidence: 96%

“…Blending lines within 1.5 Å of the line positions mostly produce a contribution that is comparable to the assumed uncertainties. See Brooks et al (2017) for details and exceptions.…”

Section: Methodsmentioning

confidence: 99%

“…To achieve this, we integrated the intensities between pre-defined wavelength limits chosen to minimize the impact of surrounding blends. We assessed the likely impact of blends in our previous work (Brooks et al 2017) using much higher spectral resolution observations of quiet and active regions from the EUV Imaging Spectrometer on the Hinode satellite (Brown et al 2008). Blending lines within 1.5 Å of the line positions mostly produce a contribution that is comparable to the assumed uncertainties.…”

Section: Methodsmentioning

confidence: 99%

“…Recently, Brooks et al (2017) detected a solar cyclic variation in the magnitude of the FIP effect in full disk integrated Sun-as-a-star spectra obtained by the Solar Dynamics Observatory. Motivated by this finding, the detections of solar cyclic variations in the Ne/O abundance ratio in the slow wind and detailed atmospheric structures, and the continuing controversy of the solar abundance problem, we decided to investigate whether the Ne/O abundance ratio depends on the solar cycle in Sun-as-a-star data.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Solar Cycle Observations of the Neon Abundance in the Sun-as-a-star

Brooks

Baker

Driel-Gesztelyi

et al. 2018

ApJ

Self Cite

View full text Add to dashboard Cite

Properties of the Sun's interior can be determined accurately from helioseismological measurements of solar oscillations. These measurements, however, are in conflict with photospheric elemental abundances derived using 3D hydrodynamic models of the solar atmosphere. This divergence of theory and helioseismology is known as the "solar modeling problem." One possible solution is that the photospheric neon abundance, which is deduced indirectly by combining the coronal Ne/O ratio with the photospheric O abundance, is larger than generally accepted. There is some support for this idea from observations of cool stars. The Ne/O abundance ratio has also been found to vary with the solar cycle in the slowest solar wind streams and coronal streamers, and the variation from solar maximum to minimum in streamers (∼0.1-0.25) is large enough to potentially bring some of the solar models into agreement with the seismic data. Here we use daily sampled observations from the EUV Variability Experiment on the Solar Dynamics Observatory taken in 2010-2014, to investigate whether the coronal Ne/O abundance ratio shows a variation with the solar cycle when the Sun is viewed as a star. We find only a weak dependence on, and moderate anti-correlation with, the solar cycle with the ratio measured around 0.2-0.3 MK falling from 0.17 at solar minimum to 0.11 at solar maximum. The effect is amplified at higher temperatures (0.3-0.6 MK) with a stronger anti-correlation and the ratio falling from 0.16 at solar minimum to 0.08 at solar maximum. The values we find at solar minimum are too low to solve the solar modeling problem.

show abstract

Section: Neon/oxygen Abundancesmentioning

confidence: 60%

Section: Introductionmentioning

confidence: 96%

“…Blending lines within 1.5 Å of the line positions mostly produce a contribution that is comparable to the assumed uncertainties. See Brooks et al (2017) for details and exceptions.…”

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Solar Cycle Observations of the Neon Abundance in the Sun-as-a-star

Brooks

Baker

Driel-Gesztelyi

et al. 2018

ApJ

Self Cite

View full text Add to dashboard Cite

show abstract

Coronal Elemental Abundance: New Results from Soft X-Ray Spectroscopy of the Sun

et al. 2020

View full text Add to dashboard Cite

Elemental abundances in the solar corona are known to be different from those observed in the solar photosphere. The ratio of coronal to photospheric abundance shows a dependence on the first ionisation potential (FIP) of the element. We estimate FIP bias from direct measurements of elemental abundances from soft X-ray spectra using data from multiple space missions covering a range of solar activity levels. This comprehensive analysis shows clear evidence for a decrease in FIP bias around maximum intensity of the X-ray flare with coronal abundances briefly tending to photospheric values and a slow recovery as the flare decays. The departure from coronal abundances are larger for the low FIP elements Ca, Fe and Si than for S which have a mid FIP value. These changes in the degree of fractionation might provide inputs to model wave propagation through the chromosphere during flares.

show abstract

Coronal Elemental Abundances During A-Class Solar Flares Observed by Chandrayaan-2 XSM

et al. 2023

View full text Add to dashboard Cite

The abundances of low First Ionisation Potential (FIP) elements are three to four times higher (FIP bias) in the closed loop active corona than in the photosphere, known as the FIP effect. Observations suggest that the abundances vary in different coronal structures. Here, we use the soft X-ray spectroscopic measurements from the Solar X-ray Monitor (XSM) on board the Chandrayaan-2 orbiter to study the FIP effect in multiple A-class flares observed during the minimum of solar cycle 24. Using time-integrated spectral analysis, we derive the average temperature, emission measure, and the abundances of four elements -Mg, Al, Si, and S. We find that the temperature and emission measure scales with the flares sub-class while the measured abundances show an intermediate FIP bias for the lower A-flares (e.g., A1), while for the higher A-flares, the FIP bias is near unity. To investigate it further, we perform a time-resolved spectral analysis for a sample of the A-class flares and examine the evolution of temperature, emission measure, and abundances. We find that the abundances drop from the coronal values towards their photospheric values in the impulsive phase of the flares, and after the impulsive phase, they quickly return to the usual coronal values. The transition of the abundances from the coronal to photospheric values in the impulsive phase of the flares indicates the injection of fresh unfractionated material from the lower solar atmosphere to the corona due to chromospheric evaporation. However, explaining the quick recovery of the abundances from the photospheric to coronal values in the decay phase of the flare is challenging.

show abstract

A Solar cycle correlation of coronal element abundances in Sun-as-a-star observations

Cited by 38 publications

References 50 publications

Solar Cycle Observations of the Neon Abundance in the Sun-as-a-star

Solar Cycle Observations of the Neon Abundance in the Sun-as-a-star

Coronal Elemental Abundance: New Results from Soft X-Ray Spectroscopy of the Sun

Coronal Elemental Abundances During A-Class Solar Flares Observed by Chandrayaan-2 XSM

Contact Info

Product

Resources

About