High-resolution X-ray spectroscopy of Procyon by Chandra   and XMM-Newton

Raassen, A. J. J.; Mewe, R.; Audard, M.; Güdel, M.; Behar, E.; Kaastra, J. S.; Meer, R. L. J. van der; Foley, C. R.; Ness, J. U.

doi:10.1051/0004-6361:20020529

Cited by 109 publications

(212 citation statements)

References 30 publications

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“…Correcting for this, we determine a revised I(86.84 Å)/I(87.02 Å) ratio of ∼1.5 which implies N e 10 9 cm −3 , in better agreement with the density derived from other diagnostics by Schmitt et al (1996). Raassen et al (2002) and Werner & Drake (2005). (b) Lines identified in solar spectra by Behring et al (1972), Malinovsky & Heroux (1973) and Acton et al (1985).…”

Section: The Soft X-ray Regionsupporting

confidence: 76%

“…9. Raassen et al (2002) found an experimental value for this ratio of 1.2 from the Chandra spectrum of Procyon. From Fig.…”

Section: The Soft X-ray Regionmentioning

confidence: 89%

“…The I(86.84 Å)/I(87.02 Å) line intensity ratio plotted as a function of logarithmic electron density (N e in cm −3 ) at logarithmic electron temperatures (T e in K) of log T e = 5.7, 5.9 and 6.1. The experimental ratio of 1.2 from the Chandra spectrum of Procyon (Raassen et al 2002) is plotted as a dashed line, while the ratio corrected for the presence of an Fe  blend in the 87.02 Å feature (1.5) is shown as a dashed-dot line.…”

Section: Discussionmentioning

confidence: 99%

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Electron impact excitation of Mg VIII

Grieve

Ramsbottom

Keenan

2013

A&A

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Context. Mg  emission lines are observed in a range of astronomical objects such as the Sun, other cool stars and in the coronal line region of Seyfert galaxies. Under coronal conditions Mg  emits strongly in the extreme ultraviolet (EUV) and soft X-ray spectral regions which makes it an ideal ion for plasma diagnostics. Aims. Two theoretical atomic models, consisting of 125 fine structure levels, are developed for the Mg  ion. The 125 levels arise from the 2s 2 2p, 2s2p 2 , 2p 3 , 2s 2 3s, 2s 2 3p, 2s 2 3d, 2s2p3s, 2s2p3p, 2s2p3d, 2p 2 3s, 2p 2 3p and 2p 2 3d configurations. Electron impact excitation collision strengths and radiative transition probabilities are calculated for both Mg  models, compared with existing data, and the best model selected to generate a set of theoretical emission line intensities. The EUV lines, covering 312-790 Å, are compared with existing solar spectra (SERTS-89 and SUMER), while the soft X-ray transitions (69-97 Å) are examined for potential density diagnostic line ratios and also compared with the limited available solar and stellar observational data. Methods. The R-matrix codes Breit-Pauli RMATRXI and RMATRXII are utilised, along with the PSTGF code, to calculate the collision strengths for two Mg  models. Collision strengths are averaged over a Maxwellian distribution to produce the corresponding effective collision strengths for use in astrophysical applications. Transition probabilities are also calculated using the CIV3 atomic structure code. The best data are then incorporated into the modelling code CLOUDY and line intensities generated for a range of electron temperatures and densities appropriate to solar and stellar coronal plasmas.Results. The present effective collision strengths are compared with two previous calculations. Good levels of agreement are found with the most recent, but there are large differences with the other for forbidden transitions. The resulting line intensities compare favourably with the observed values from the SERTS-89 and SUMER spectra. Theoretical soft X-ray emission lines are presented and several density diagnostic line ratios examined, which are in reasonable agreement with the limited observational data available.

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Section: The Soft X-ray Regionsupporting

confidence: 76%

“…9. Raassen et al (2002) found an experimental value for this ratio of 1.2 from the Chandra spectrum of Procyon. From Fig.…”

Section: The Soft X-ray Regionmentioning

confidence: 89%

Section: Discussionmentioning

confidence: 99%

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Electron impact excitation of Mg VIII

Grieve

Ramsbottom

Keenan

2013

A&A

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“…Audard et al (2003) showed a similar transitions from an inverse FIP effect to the absence of an obvious FIP effect for RS CVn binary stars with decreasing activity. Only one star studied in detail to date on the basis of high-resolution spectra appears to have a coronal composition demonstrably similar to that of its underlying photosphere: the subgiant Procyon (F5 IV; Drake et al 1995;Raassen et al 2002).…”

Section: Introductionmentioning

confidence: 99%

The Coronae of AB Doradus and V471 Tauri: Primordial Angular Momentum versus Tidal Spin‐up

García-Álvarez

Drake

Lin

et al. 2005

ApJ

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The zero-age main-sequence star AB Dor and the K dwarf component of the V471 Tau close binary have essentially identical rotation rates and spectral types. An analysis of their high-resolution Chandra X-ray spectra reveals remarkably similar coronal characteristics in terms of both temperature structure and element abundances. Both stars show depletions of low first ionization potential (FIP) elements by factors of $3, with higher FIP elements showing more mild depletions. No evidence for enhancements of very low FIP (<7 eV) elements, such as Na, Al, and Ca, as compared to other low-FIP elements, was found. The abundance anomaly pattern for AB Dor and V471 Tau is similar to, although less extreme than, the abundance anomalies exhibited by active RS CVn-type binaries. While we find statistically significant structure in the underlying differential emission measure distributions of these stars over narrow temperature intervals, this structure is strongly dependent on the lines used in the analysis and is probably spurious. On the basis of their X-ray similarities, we conclude that the exact evolutionary state of a star has little effect on coronal characteristics and that the parameters that dominate coronal structure and composition are simply the rotation rate and spectral type.

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“…The authors also propose that Alfvén waves, combined with pondermotive forces, would explain the observed FIP effect on the Sun, pointing towards the disappearance of any Article published by EDP Sciences , BR00 (Brickhouse et al 2000), FE00 (Feldman & Laming 2000), HU01 (Huenemoerder et al 2001), HU03 (Huenemoerder et al 2003), RA02 (Raassen et al 2002), SF04 (Sanz-Forcada et al 2004), SF03 (Sanz-Forcada et al 2003b). …”

Section: Introductionmentioning

confidence: 99%

No first ionization potential fractionation in the active stars AR Piscium and AY Ceti

Sanz-Forcada

Affer

Micela

2009

A&A

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Context. The comparison of coronal and photospheric abundances in cool stars is an essential question to resolve. In the Sun an enhancement of the elements with low first ionization potential (FIP) is observed in the corona with respect to the photosphere. Stars with high levels of activity seem to show a depletion of elements with low FIP when compared to solar standard values; however, the few cases of active stars in which photospheric values are available for comparison lead to confusing results, and an enlargement of the sample is mandatory for solving this longstanding problem. Aims. We calculate in this paper the photospheric and coronal abundances of two well known active binary systems, AR Psc and AY Cet, to get further insight into the complications of coronal abundances. Methods. Coronal abundances of 9 elements were calculated by means of the reconstruction of a detailed emission measure distribution, using a line-based method that considers the lines from different elements separately. Photospheric abundances of 8 elements were calculated using high-resolution optical spectra of the stars. Results. The results once again show a lack of any FIP-related effect in the coronal abundances of the stars. The presence of metal abundance depletion (MAD) or inverse FIP effects in some stars could stem from a mistaken comparison to solar photospheric values or from a deficient calculation of photospheric abundances in fast-rotating stars. Conclusions. The lack of FIP fractionation seems to confirm that Alfvén waves combined with pondermotive forces are dominant in the corona of active stars.

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High-resolution X-ray spectroscopy of Procyon by Chandra and XMM-Newton

Cited by 109 publications

References 30 publications

Electron impact excitation of Mg VIII

Electron impact excitation of Mg VIII

The Coronae of AB Doradus and V471 Tauri: Primordial Angular Momentum versus Tidal Spin‐up

No first ionization potential fractionation in the active stars AR Piscium and AY Ceti

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