A Solar Spectroscopic Absolute Abundance of Argon From Resik

Sylwester, J.; Sylwester, B.; Phillips, K. J. H.; Кузнецов, В. Д.

doi:10.1088/0004-637x/720/2/1721

Cited by 17 publications

(38 citation statements)

References 29 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Sterling et al (1993) found that the calcium abundance in 25 events was on average about a factor of two greater than photospheric, indicating a coronal flare abundance. Sylwester et al (2010Sylwester et al ( , 2015 found argon abundances that are nearly the same as the Lodders (2008) argon abundance that we used in Doschek et al (2015). A photospheric argon abundance is expected if the low-FIP elements are enhanced in the corona.…”

Section: Introductionsupporting

confidence: 61%

“…We used the same abundance sources as given in Doschek et al (2015): the calcium abundance is from Caffau et al (2011), and the argon abundance is from Lodders (2008). As mentioned, the Lodders (2008) argon abundance is nearly the same as found in flares by Sylwester et al (2010Sylwester et al ( , 2015. The photospheric line ratio is about unity.…”

Section: Eis Argon Spectramentioning

confidence: 99%

See 1 more Smart Citation

The Mysterious Case of the Solar Argon Abundance Near Sunspots in Flares

Doschek

Warren

2016

ApJ

View full text Add to dashboard Cite

Recently we discussed an enhancement of the abundance of Ar XIV relative to Ca XIV near a sunspot during a flare, observed in spectra recorded by the Extreme-ultraviolet Imaging Spectrometer (EIS) on the Hinode spacecraft. The observed Ar XIV/Ca XIV ratio yields an argon/calcium abundance ratio seven times greater than expected from the photospheric abundance. Such a large abundance anomaly is unprecedented in the solar atmosphere. We interpreted this result as being due to an inverse first ionization potential (FIP) effect. In the published work, two lines of Ar XIV were observed, and one line was tentatively identified as an Ar XI line. In this paper, we report observing a similar enhancement in a full-CCD EIS flare spectrum in 13 argon lines that lie within the EIS wavelength ranges. The observed lines include two Ar XI lines, four Ar XIII lines, six Ar XIV lines, and one Ar XV line. The enhancement is far less than reported in Doschek et al. but exhibits similar morphology. The argon abundance is close to a photospheric abundance in the enhanced area, and the abundance could be photospheric. This enhancement occurs in association with a sunspot in a small area only a few arcseconds (1″ = about 700 km) in size. There is no enhancement effect observed in the normally high-FIP sulfur and oxygen line ratios relative to lines of low-FIP elements available to EIS. Calculations of path lengths in the strongest enhanced area in Doschek et al. indicate a depletion of low-FIP elements.

show abstract

Section: Introductionsupporting

confidence: 61%

Section: Eis Argon Spectramentioning

confidence: 99%

The Mysterious Case of the Solar Argon Abundance Near Sunspots in Flares

Doschek

Warren

2016

ApJ

View full text Add to dashboard Cite

show abstract

“…Here, for consistency with calculations of satellites of lower ionization stages, apart from a few exceptions we used the Cowan Hartree-Fock atomic code (Cowan 1981) to calculate the necessary data. This code was run previously in studies we made of X-ray dielectronic satellites of Li-like K and Cl seen with the RESIK instrument (Sylwester et al 2010b(Sylwester et al , 2011. The code 1 , outlined in Cowan (1981) (3) and (4) with g 1 = 2 for Ca XVII satellites (excitation from the ground level 1s 2 2s 2 S 1/2 of Ca +17 with statistical weight 2), 1 for Ca XVI (excitation from 1s 2 2s 2 1 S 0 of Ca +16 ), and 2 for Ca XV (excitation from 1s 2 2s 2 2p 2 P 1/2 of Ca +15 ).…”

Section: Ca XVIII -Ca Xv Dielectronic Satellitesmentioning

confidence: 99%

Highly Ionized Calcium and Argon X-Ray Spectra from a Large Solar Flare

Phillips

Sylwester

et al. 2018

ApJ

Self Cite

View full text Add to dashboard Cite

X-ray lines of helium-like calcium (Ca XIX) between 3.17 Å and 3.21 Å and associated Ca XVIII dielectronic satellites have previously been observed in solar flare spectra, and their excitation mechanisms are well established. Dielectronic satellites of lower ionization stages (Ca XVII -Ca XV) are not as well characterized. Several spectra during a large solar flare in 2001 by the DIOGENESS X-ray spectrometer on the CORONAS-F spacecraft show the Ca XVII and Ca XVI satellites as well as lines of ionized argon (Ar XVII, Ar XVI) including dielectronic satellites. The DIOGENESS spectra are compared with spectra from a synthesis code developed here based on an isothermal assumption with various atomic sources including dielectronic satellite data from the Cowan Hartree-Fock code. Best-fit comparisons are made by varying the temperature as the code's input (Ar/Ca abundance ratio fixed at 0.33); close agreement is achieved although with adjustments to some ion fractions. The derived temperature is close to that derived from the two GOES X-ray channels, T GOES . Some lines are identified for the first time. Similar spectra from the P78-1 spacecraft and the Alcator C-Mod tokamak have also been analyzed and similar agreement obtained. The importance of blends of calcium and argon lines is emphasized, affecting line ratios used for temperature diagnostics. This analysis will be applied to the Solar Maximum Mission Bent Crystal Spectrometer archive and to X-ray spectra expected from the ChemiX instrument on the Sun-orbiting Interhelioprobe spacecraft, while the relevance to X-ray spectra from non-solar sources is indicated.

show abstract

“…Figure 2 shows RESIK channel 1 spectra extracted from the new data set and summed over narrow regions of temperature T GOES , taken to be that estimated from the flux ratio of the two X-ray channels of the Geostationary Operational Environmental Satellites (GOES). Our previous work has indicated that T GOES is an accurate representation of temperature for the K XVIII lines as well as Ar XVII lines seen in channel 2 (Sylwester et al 2010a where N e = electron density and V = emitting volume) for each RESIK spectrum were estimated from the ratio of the observed spectral flux to the theoretical spectral flux from the CHIANTI code at the temperature T GOES . The vertical scale in Figure 2 is flux (photon cm −2 s −1 keV −1 ) normalized to a volume emission measure of 10 48 cm −3 .…”

Section: Observationsmentioning

confidence: 99%

THE X-RAY LINE FEATURE AT 3.5 KeV IN GALAXY CLUSTER SPECTRA

Phillips

Sylwester

2015

ApJ

Self Cite

View full text Add to dashboard Cite

Recent work by Bulbul et al. and Boyarsky et al. has suggested that a line feature at ∼3.5 keV in the X-ray spectra of galaxy clusters and individual galaxies seen with XMM-Newton is due to the decay of sterile neutrinos, a dark matter candidate. This identification has been criticized by Jeltema & Profumo on the grounds that model spectra suggest that atomic transitions in helium-like potassium (K XVIII) and chlorine (Cl XVI) are more likely to be the emitters. Here it is pointed out that the K XVIII lines have been observed in numerous solar flare spectra at high spectral resolution with the RESIK crystal spectrometer and also appear in Chandra HETG spectra of the coronally active star σ Gem. In addition, the solar flare spectra at least indicate a mean coronal potassium abundance, which is a factor between 9 and 11 higher than the solar photospheric abundance. This fact, together with the low statistical quality of the XMM-Newton spectra, completely account for the ∼3.5 keV feature and there is therefore no need to invoke a sterile neutrino interpretation of the observed line feature at ∼3.5 keV.

show abstract

A Solar Spectroscopic Absolute Abundance of Argon From Resik

Cited by 17 publications

References 29 publications

The Mysterious Case of the Solar Argon Abundance Near Sunspots in Flares

The Mysterious Case of the Solar Argon Abundance Near Sunspots in Flares

Highly Ionized Calcium and Argon X-Ray Spectra from a Large Solar Flare

THE X-RAY LINE FEATURE AT 3.5 KeV IN GALAXY CLUSTER SPECTRA

Contact Info

Product

Resources

About