High-Resolution X-Ray Spectra of Capella: Initial Results from the [ITAL]Chandra[/ITAL] High-Energy Transmission Grating Spectrometer

Canizares, C. R.; Huenemoerder, David P.; Davis, David; Dewey, Daniel; Flanagan, Kathryn A.; Houck, J. C.; Markert, T. H.; Marshall, Herman L.; Schattenburg, Mark L.; Schulz, Norbert S.; Wise, Michael; Drake, J. J.; Brickhouse, N. S.

doi:10.1086/312823

Cited by 177 publications

(104 citation statements)

References 19 publications

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“…Ne , O , and Fe Lshell lines dominate the RGS spectra. In contrast to the other RS CVn binaries in our sample, the Capella X-ray spectrum is softer and dominated by bright Fe  and Fe  lines as previously observed (e.g., Brinkman et al 2000;Canizares et al 2000;Audard et al 2001b;Behar et al 2001;Mewe et al 2001). We provide the high-energy EPIC MOS2 spectra in Fig.…”

Section: Resultsmentioning

confidence: 73%

A study of coronal abundances in RS CVn binaries

Audard

Güdel

Sres

et al. 2003

A&A

106

129

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Abstract. We present XMM-Newton data of several RS CVn binary systems. High-resolution X-ray spectra obtained with the Reflection Grating Spectrometers have been interpreted simultaneously with the European Photon Imaging Camera spectra. Highly active stars show a depletion of elements with a low first ionization potential (FIP) relative to high-FIP elements, whereas intermediately active binaries show either no FIP bias or a possible solar-like FIP effect. We find that the low-FIP abundance ratios to oxygen vary with the coronal average temperature whereas the ratios for high-FIP elements stay constant. Since we observe that the absolute Fe (low-FIP) abundance increases with decreasing activity, this suggests that the abundances of elements with low FIP vary with the coronal activity level. Compared with laboratory measurements of the intensity ratios of the Fe  λλ 15.01 and 15.26 Å lines, the coronal plasmas are in the optically thin regime.

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Section: Resultsmentioning

confidence: 73%

A study of coronal abundances in RS CVn binaries

Audard

Güdel

Sres

et al. 2003

A&A

106

129

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“…On top of the graph are densities given assuming φ/φ c = 0 and using the atomic parameters listed in Table 6. that no meaningful conclusions can be drawn, while in one case (Capella) our measurement agrees perfectly with the lowdensity limit. This low-density for Capella is consistent with the XMM-Newton RGS results, but inconsistent with the measurements obtained with the Chandra MEG (cf., e.g., Canizares et al 2000;Ayres et al 2001;Phillips et al 2001). …”

Section: Discussionmentioning

confidence: 99%

“…Measurements with the MEG on board Chandra were presented by, e.g., Canizares et al (2000), Ayres et al (2001), and Phillips et al (2001). The MEG and HEG provide the highest resolution at energies >1 keV and Brickhouse et al (2001) report the measurements of orbit related line shifts in 44 Boo, thus eventually opening up the road to X-Ray Doppler imaging of stellar coronae.…”

Section: Introductionmentioning

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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“…When this is done the resulting HRMA−HETG−ACIS-S configuration is the high-energy transmission grating spectrometer (HETGS, often used interchangeably with just HETG). The HETG and its operation are described as a part of Chandra (Weisskopf et al 2000(Weisskopf et al , 2002 and in HETG-specific publications (Canizares et al 2000(Canizares et al , 2005.…”

Section: Instrumentsmentioning

confidence: 99%

SNR 1E 0102.2-7219 as an X-ray calibration standard in the 0.5−1.0 keV bandpass and its application to the CCD instruments aboardChandra,Suzaku,SwiftandXMM-Newton

Plucinsky

Beardmore

Foster

et al. 2016

A&A

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Context. The flight calibration of the spectral response of charge-coupled device (CCD) instruments below 1.5 keV is difficult in general because of the lack of strong lines in the on-board calibration sources typically available. This calibration is also a function of time due to the effects of radiation damage on the CCDs and/or the accumulation of a contamination layer on the filters or CCDs. Aims. We desire a simple comparison of the absolute effective areas of the current generation of CCD instruments onboard the following observatories: Chandra ACIS-S3, XMM-Newton (EPIC-MOS and EPIC-pn), Suzaku XIS, and Swift XRT and a straightforward comparison of the time-dependent response of these instruments across their respective mission lifetimes. Methods. We have been using 1E 0102.2-7219, the brightest supernova remnant in the Small Magellanic Cloud, to evaluate and modify the response models of these instruments. 1E 0102.2-7219 has strong lines of O, Ne, and Mg below 1.5 keV and little or no Fe emission to complicate the spectrum. The spectrum of 1E 0102.2-7219 has been well-characterized using the RGS gratings instrument on XMM-Newton and the HETG gratings instrument on Chandra. As part of the activities of the International Astronomical Consortium for High Energy Calibration (IACHEC), we have developed a standard spectral model for 1E 0102.2-7219 and fit this model to the spectra extracted from the CCD instruments. The model is empirical in that it includes Gaussians for the identified lines, an absorption component in the Galaxy, another absorption component in the SMC, and two thermal continuum components with different temperatures. In our fits, the model is highly constrained in that only the normalizations of the four brightest lines/line complexes (the O vii Heα triplet, O viii Lyα line, the Ne ix Heα triplet, and the Ne x Lyα line) and an overall normalization are allowed to vary, while all other components are fixed. We adopted this approach to provide a straightforward comparison of the measured line fluxes at these four energies. We have examined these measured line fluxes as a function of time for each instrument after applying the most recent calibrations that account for the time-dependent response of each instrument. Results. We performed our effective area comparison with representative, early mission data when the radiation damage and contamination layers were at a minimum, except for the XMM-Newton EPIC-pn instrument which is stable in time. We found that the measured fluxes of the O vii Heα r line, the O viii Lyα line, the Ne ix Heα r line, and the Ne x Lyα line generally agree to within ±10% for all instruments, with 38 of our 48 fitted normalizations within ±10% of the IACHEC model value. We then fit all available observations of 1E 0102.2-7219 for the CCD instruments close to the on-axis position to characterize the time dependence in the 0.5−1.0 keV band. We present the measured line normalizations as a function of time for each CCD instrument so that the users may estimate the un...

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High-Resolution X-Ray Spectra of Capella: Initial Results from the [ITAL]Chandra[/ITAL] High-Energy Transmission Grating Spectrometer

Cited by 177 publications

References 19 publications

A study of coronal abundances in RS CVn binaries

A study of coronal abundances in RS CVn binaries

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

SNR 1E 0102.2-7219 as an X-ray calibration standard in the 0.5−1.0 keV bandpass and its application to the CCD instruments aboardChandra,Suzaku,SwiftandXMM-Newton

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