Helium-like triplet density diagnostics: Applications to CHANDRA--LETGS X-ray observations of Capella and Procyon

Abstract

Electron density diagnostics based on the triplets of Helium-like CV, NVI, and OVII 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 derived 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=10^6K 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 CV, NVI, and OVII emission. Assuming the X-ray emitting plasma to be confined in magnetic loops, we obtain typical loop length scales of L_Capella > 8 L_Procyon 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.

arXiv comment13 pages, Latex, fitting program Cora available at http://www.hs.uni-hamburg.de/german/persons/Ness/Software/cora-1.0.tar.gz accepted at A&A under MS10283

References in corpus (2)

• X-ray photoionized plasma diagnostics with Helium-like ions. Application to Warm Absorber-Emitter in Active Galactic Nuclei
• First Light Measurements of Capella with the Low Energy Transmission Grating Spectrometer aboard the Chandra X-ray Observatory

Cited by in corpus (44)

• Optimal binning of X-ray spectra and response matrix design
• X-Ray Spectroscopy of Stars
• Line ratios for Helium-like ions: Applications to collision-dominated plasmas
• X-ray emission from a metal depleted accretion shock onto the classical T Tauri star TW Hya
• Flares from small to large: X-ray spectroscopy of Proxima Centauri with XMM-Newton
• On the sizes of stellar X-ray coronae
• Ultra-Wideband Detection of 22 Coherent Radio Bursts on M Dwarfs
• High-resolution X-ray spectroscopy of Procyon by Chandra and XMM-Newton
• The Density of Coronal Plasma in Active Stellar Coronae
• Stellar coronal astronomy - a review
• Coronal density diagnostics with Helium-like triplets: CHANDRA--LETGS observations of Algol, Capella, Procyon, Eps Eri, Alpha Cen A&B, UX Ari, AD Leo, YY Gem, and HR1099
• Modeling the NeIX Triplet Spectral Region of Capella with the Chandra and XMM-Newton Gratings
• The X-ray spectrum of Fe XVII revisited with a multi-ion model
• The first high-resolution X-ray spectrum of a Herbig Star: The case of AB Aurigae
• Are stellar coronae optically thin in X-rays? - A systematic investigation of opacity effects
• High-resolution X-ray spectroscopy of the evolving shock in the 2006 outburst of RS Ophiuchi
• Simultaneous X-ray spectroscopy of YY Gem with Chandra and XMM-Newton
• From X-ray dips to eclipse: Witnessing disk reformation in the recurrent nova USco
• Chandra LETGS Observation of the Active Binary Algol
• Thomson Scattering and Collisional Ionization in the X-rays Grating Spectra of the Recurrent Nova U Scorpii
• The weak-line T Tauri star V410Tau I. A multi-wavelength study of variability
• An X-ray emission line spectrum of Nova V382 Velorum 1999
• X-ray Spectroscopy of the Contact Binary VW Cephei
• X-ray absorption via K-alpha resonance complexes in oxygen ions
• On the nature of the X-ray source in GK Per
• X-ray spectra of the Fe-L complex II: atomic data constraints from EBIT experiment and X-ray grating observations of Capella
• X-ray warm absorption and emission in the polar scattered Seyfert 1 galaxy MRK 704
• XMM-Newton observations of Zeta Orionis (O9.7 Ib): A Collisional Ionization Equilibrium model
• The corona and upper transition region of epsilon Eridani
• The various accretion modes of AM Herculis: Clues from multi-wavelength observations in high accretion states
• X-ray spectra of the Fe-L complex III: systematic uncertainties in the atomic data
• Electron density diagnostic potential of Ar XIV soft X-ray emission lines
• An R-matrix with pseudo-state (RMPS) approach to the single photon double ionization and excitation of the He-like Li${}^{+}$ ion
• Castor A and Castor B resolved in a simultaneous Chandra and XMM-Newton observation
• Electron density diagnostic for hot plasmas in coronal regime by using B-like ions
• Coronal density diagnostics with Si X: CHANDRA/LETGS observations of Procyon, $\alpha$ Cen A$&$B, Capella and $\epsilon$ Eri
• Soft X-ray emissions of highly charged Si VII--Si XII in cool star--Procyon
• X-ray variability of cool stars: Magnetic activity and accretion
• Soft X-ray spectroscopy of highly charged silicon ions in dense plasmas
• Analysis of Solar-like X-Class Flare on Wolf 359 Observed Simultaneously with TESS and XMM-Newton
• Soft X-ray emissions of Si IX in Procyon
• Determinations of temperature and density for solar-like Stars using Si XI soft X-ray emission lines
• Analytical approximations to numerical solutions of theoretical emission measure distributions
• A benchmark of the He-like triplet for ions with $6\le Z\le 14$ in Maxwellian and non-Maxwellian plasmas