Diagnostic application of highly ionized iron lines in the XUV spectrum of a solar flare

Mason, H. E.; Bhatia, A. K.; Kastner, S. O.; Neupert, W. M.; Swartz, M.

doi:10.1007/bf00157246

Cited by 41 publications

(48 citation statements)

References 26 publications

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“…This range was used by, e.g., Mewe et al (2001) and Ness et al (2002a) for an independent density analysis with Fe  line ratios (cf. Mason et al 1984).…”

Section: The Instrumentmentioning

confidence: 99%

Coronal density diagnostics with Helium-like triplets: CHANDRA–LETGS observations of Algol, Capella, Procyon,ϵ Eri,α Cen A&B, UX Ari, AD Leo, YY Gem, and HR 1099

Ness

Schmitt

Burwitz

et al. 2002

A&A

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Coronal density diagnostics with Helium-like triplets: CHANDRA-LETGS observations of Algol, Capella, Procyon, epsilon Eri, alpha Cen A&B, UX Ari, AD Leo, YY Gem, and HR 1099 Ness, J.-U.; Schmitt, J.H.M.M.; Burwitz, V.; Mewe, R.; Raassen, A.J.J.; van der Meer, R.L.J.; Predehl, P.; Brinkman, A.C. Disclaimer/Complaints regulationsIf you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: http://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. Abstract. We present an analysis of ten cool stars (Algol, Capella, Procyon, Eri, α Cen A&B, UX Ari, AD Leo, YY Gem, and HR 1099) observed with the Low Energy Transmission Grating Spectrometer (LETGS) on board the Chandra X-ray Observatory. This sample contains all cools stars observed with the LETGS presently available to us with integration times sufficiently long to warrant a meaningful spectral analysis. Our sample comprises inactive, moderately active, and hyperactive stars and samples the bulk part of activity levels encountered in coronal X-ray sources. We use the LETGS spectra to carry out density and temperature diagnostics with an emphasis on the H-like and the He-like ions. We find a correlation between line flux ratios of the Ly α and He-like resonance lines with the mean X-ray surface flux. We determine densities using the He-like triplets. For all stars we find no significant deviations from the low-density limit for the ions of Ne, Mg, and Si, while the measured line ratios for the ions of C, N, and O do show evidence for departures from the low-density limit in the active stars, but not in the inactive stars. Best measurements can be made for the O  triplet where we find significant deviations from the low-density limit for the stars Algol, Procyon, YY Gem, Eri, and HR 1099. We discuss the influence of radiation fields on the interpretation of the He-like triplet line ratios in the low-Z ions, which is relevant for Algol, and the influence of dielectronic satellite lines, which is relevant for Procyon. For the active stars YY Gem, Eri, and HR 1099 the low f /i ratios can unambiguously be attributed to high densties in the range 1-3× 10 10 cm −3 at O  temperatures. We find our LETGS spectra to be an extremely useful tool for plasma diagnostics of stellar coronae.

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“…This range was used by, e.g., Mewe et al (2001) and Ness et al (2002a) for an independent density analysis with Fe  line ratios (cf. Mason et al 1984).…”

Section: The Instrumentmentioning

confidence: 99%

Coronal density diagnostics with Helium-like triplets: CHANDRA–LETGS observations of Algol, Capella, Procyon,ϵ Eri,α Cen A&B, UX Ari, AD Leo, YY Gem, and HR 1099

Ness

Schmitt

Burwitz

et al. 2002

A&A

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“…The kernels of the loop footpoint were found to have high densities, and the profiles of lines formed around 3 MK were found to be strongly blue-shifted. The old Skylab X-ray observations of X-ray kernels (Kahler et al 1975(Kahler et al , 1976Mason et al 1984) were revisited, suggesting that those kernels were due to high densities at 6−8 MK (Fe xvii) caused by the chromospheric evaporation process.…”

Section: Introductionmentioning

confidence: 99%

“…These lines were observed for the first (and only) time by OSO 5, as described by Kastner et al (1974). They provide a range of diagnostic possibilities, mostly to measure temperatures and densities of the flare plasma (Mason et al 1984).…”

Section: Introductionmentioning

confidence: 99%

SDO AIA and EVE observations and modelling of solar flare loops

Petkaki

Zanna

Mason

et al. 2012

A&A

Self Cite

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We present imaging and spectroscopic observations of an isolated C1-class solar flare, obtained with the Atmospheric Imaging Assembly (AIA) and Extreme ultraviolet Variability Experiment (EVE) on the Solar Dynamics Observatory (SDO). We obtain excellent agreement between the peak flare temperatures estimated using the EVE spectra with those obtained from GOES and, most importantly, from the ratio of the 94 Å and 131 Å AIA channels, which are found to be dominated by Fe xviii and Fe xxi. These results confirm that these two AIA bands can be reliably used to provide temperature diagnostics for the peak and gradual phases of solar flares. The flare kernels, probable sources of chromospheric evaporation, are seen as strong localised emission in the AIA bands at the footpoints of flare loops. The flare loops are close to isothermal during the gradual phase. We have run several hydrodynamic simulations (using the HYDRAD code) to study the cooling of the flare loops. We find good overall agreement between observed and predicted electron temperatures and densities when a gradual increase and decrease of the heating is assumed.

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“…In this review paper we discuss the wavelength region 1 -200A giving a few specific examples. Mason et al (1979).…”

Section: Excited Levelmentioning

confidence: 99%

“…These data were obtained by Kastner et al (1974) with the OSO-5 satellite (figure 3 ) . This spectral range which has great diagnostic potential (see Mason et al, 1984) has been sadly neglected. In figure 4 is shown a spectrum of Capella obtained by the transmission grating spectrometer on EXOSAT.…”

Section: Highly Ionised Iron Ionsmentioning

confidence: 99%

Spectroscopic Diagnostics for Ions Observed in Solar and Cosmic Plasmas

Mason

1990

International Astronomical Union Colloquium

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ABSTRACT. The X-ray wavelength region (1-200A) is rich in spectral lines from highly ionised systems. Spectra from the solar atmosphere have been studied extensively with various instruments covering different wavelength regions. In this paper, we discuss the solar spectral line emission with particular reference to iron ions and helium like ions observed during solar flares. The atomic processes involved in the calculation of theoretical intensities for low density plasmas are outlined together with the diagnostic properties of the emission lines. Comparisons are made with available cosmic X-ray spectra and predicted spectra for future projects, such as AXAF.

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Diagnostic application of highly ionized iron lines in the XUV spectrum of a solar flare

Cited by 41 publications

References 26 publications

Coronal density diagnostics with Helium-like triplets: CHANDRA–LETGS observations of Algol, Capella, Procyon,ϵ Eri,α Cen A&B, UX Ari, AD Leo, YY Gem, and HR 1099

Coronal density diagnostics with Helium-like triplets: CHANDRA–LETGS observations of Algol, Capella, Procyon,ϵ Eri,α Cen A&B, UX Ari, AD Leo, YY Gem, and HR 1099

SDO AIA and EVE observations and modelling of solar flare loops

Spectroscopic Diagnostics for Ions Observed in Solar and Cosmic Plasmas

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