Stellar coronal abundances. 2: The first ionization potential effect and its absence in the corona of procyon

Drake, J. J.; Laming, J. M.; Widing, K. G.

doi:10.1086/175533

Cited by 117 publications

(75 citation statements)

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“…41 We have used the emission measure distribution A . of Procyon (Drake et al 1995) and the line emissivities of Brickhouse et al (1995) and estimate that the Fe X line contributes D20% to the 180 feature. We next compare A the density-insensitive ratio to theory.…”

Section: Procyon Spectramentioning

confidence: 99%

“…They also used Fe X and Fe XIIÈFe XIV lines to constrain the density of Procyon to 109È1010 cm~3. Drake, Laming, & Widing (1995) presented a detailed study of element abundances in the corona of Procyon, and discussed the Ðrst ionization potential e †ect (or apparent lack of it). Schmitt et al (1996) measured density-sensitive line ratios from Fe XÈFe XIV in Procyon, and derived a coronal density consistent with solar active regions.…”

Section: Introductionmentioning

confidence: 99%

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Electron Densities in the Coronae of the Sun and Procyon from Extreme‐Ultraviolet Emission Line Ratios in Fexi

Pinfield

Keenan

Mathioudakis

et al. 2001

ApJ

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New R-matrix calculations of electron impact excitation rates for Fe XI are used to determine theoretical emission line ratios applicable to solar and stellar coronal observations. These are subsequently compared to solar spectra of the quiet Sun and an active region made by the Solar EUV Rocket Telescope and Spectrograph (SERTS-95), as well as Skylab observations of two Ñares. Line blending is identiÐed, and electron densities of 109.3, 109.7, º1010.8, and º1011.3 cm~3 are found for the quiet Sun, active region, and the two Ñares, respectively. Observations of the F5 IVÈV star Procyon, made with the Extreme Ultraviolet Explorer (EUV E) satellite, are compared and contrasted with the solar observations. It is conÐrmed that ProcyonÏs average coronal conditions are very similar to those seen in the quiet Sun, with cm~3. In addition, although the quiet Sun is the closest solar analog to Procyon, we N e \ 109.4 conclude that ProcyonÏs coronal temperatures are slightly hotter than solar. A Ðlling factor of 25~1 2 38% was derived for the corona of Procyon.

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Section: Procyon Spectramentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Electron Densities in the Coronae of the Sun and Procyon from Extreme‐Ultraviolet Emission Line Ratios in Fexi

Pinfield

Keenan

Mathioudakis

et al. 2001

ApJ

Self Cite

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“…5 Kelch et al (1978). Lemen et al (1989) using EXOSAT transmission grating data and Drake et al (1995) and Schrijver et al (1995) using EUVE data. Note that Schmitt et al (1996b) and Schrijver et al (1995) investigated the coronal density of Procyon using a variety of density sensitive lines from Fe x to Fe xiv in the EUV range and found Procyon's coronal density consistent with that of solar active region densities.…”

Section: Introductionmentioning

confidence: 99%

Helium-like triplet density diagnostics

Ness

Mewe

Schmitt

et al. 2001

A&A

101

137

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Abstract. Electron density diagnostics based on the triplets of helium-like C v, N vi, and O vii are applied to the X-ray spectra of Capella and Procyon measured with the Low Energy Transmission Grating Spectrometer (LETGS) on board the Chandra X-ray Observatory. New theoretical models for the calculation of the line ratios between the forbidden (f ), intercombination (i), and the resonance (r) lines of the helium-like triplets are used. The (logarithmic) electron densities (in cgs units) derived from the f/i ratios for Capella are < 9.38 cm −3 for O vii (2σ upper limit) (f/i = 4.0 ± 0.25), 9.86 ± 0.12 cm −3 for N vi (f/i = 1.78 ± 0.25), and 9.42 ± 0.21 cm −3 for C v (f/i = 1.48 ± 0.34), while for Procyon we obtain 9.28for N vi (f/i = 1.33 ± 0.28), and < 8.92 cm −3 for C v (f/i = 0.48 ± 0.12). These densities are quite typical of densities found in the solar active regions, and also pressures and temperatures in Procyon's and Capella's corona at a level of T ∼ 10 6 K are quite similar. We find no evidence for densities as high as measured in solar flares. Comparison of our Capella and Procyon measurements with the Sun shows little difference in the physical properties of the layers producing the C v, N vi, and O vii emission. Assuming the X-ray emitting plasma to be confined in magnetic loops, we obtain typical loop length scales of L Capella ≥ 8 LProcyon from the loop scaling laws, implying that the magnetic structures in Procyon and Capella are quite different. The total mean surface fluxes emitted in the helium-and hydrogen-like ions are quite similar for Capella and Procyon, but exceed typical solar values by one order of magnitude. We thus conclude that Procyon's and Capella's coronal filling factors are larger than corresponding solar values.

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“…Audard et al (2003) have merged the results from the solar analogs and the RS CVn binaries and showed a significant anti-correlation between the average coronal temperature of a star and its Fe/O abundance ratio; they also showed that the Ne/O ratio is, however, not temperature-sensitive. This scheme may be too simplistic: previous observations with EUVE showed that the old, inactive Procyon displays no FIP bias at all (Drake et al 1995), which is confirmed with XMM-Newton and Chandra LETG (Raassen et al, 2002), while a solar-like FIP effect could be expected. There is a clear need for a comprehensive study of the coronal composition in stars of all activity levels.…”

Section: The Elemental Composition Of Stellar Coronaementioning

confidence: 89%

Investigations of stellar coronae with XMM-Newton

Audard

2003

Advances in Space Research

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The XMM-Newton observatory has given a strong new impetus to the investigations of stellar coronae. It carries high-resolution X-ray spectroscopic instruments that give access to information on the physical conditions in coronal plasmas. Furthermore, its imaging detectors produce high-quality X-ray light curves and images with a large field of view. I review results on stellar coronae obtained with XMM-Newton between its launch in late 1999 and the present (late 2002). Among other topics, I discuss the elemental composition of stellar coronae and plasma electron densities in quiescence and during flares. I present evidence for various signatures of the Neupert effect in stars, which provides evidence of chromospheric and coronal heating by flares. Coronal structures based on eclipse mapping inferred from light curve inversion are shown.

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Stellar coronal abundances. 2: The first ionization potential effect and its absence in the corona of procyon

Cited by 117 publications

References 0 publications

Electron Densities in the Coronae of the Sun and Procyon from Extreme‐Ultraviolet Emission Line Ratios in Fexi

Electron Densities in the Coronae of the Sun and Procyon from Extreme‐Ultraviolet Emission Line Ratios in Fexi

Helium-like triplet density diagnostics

Investigations of stellar coronae with XMM-Newton

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