Soft X-ray emissions of highly charged Si VII--Si XII in cool star--Procyon

Abstract

Different observation data for cool star--Procyon (Obs\_IDs of 63, 1461 and 1224) available from {\it Chandra Data Public Archive} were co-added and analyzed. Emissivities of emission lines of highly charged silicon ions (Si VII--Si XII) were calculated over temperatures by adopting the published data of Liang et al. (2007, {\it Atom. Data and Nucl. Data Tables}, {\bf 93}, 375). Using the emission measure derived by Raassen et al. (2002, A&A, {\bf 389}, 228), the theoretical line fluxes are predicted, and the theoretical spectra are constructed by assuming the Gaussian profile with instrumental broadening (0.06 Å). By detailed comparison between observation and predictions, several emissions lines are identified firstly such as emissions at 43.663 Å(Si XI), 45.550 Å(Si XII), 46.179 Å(Si VIII), 50.874 Å(Si X), 64.668 Å(Si IX), and 73.189 Å(Si VII) etc. Several emission lines are re-assigned in this work, such as the emission line at 52.594 Åto Si X (52.612 Å), at 69.641 Åto the blending of Si VII (69.632 Å) and Si VIII (69.664 Å) lines, as well as at 70.050 Åto Si VII (70.027 Å). The prediction reveals the large discrepancies between the $3s$--$2p$ line (63.715 Å) {\it versus} 3d--$2p$ line (61.012 Å) again for lower charge stage Si VIII. Solar flare observation is also added for the assessment of present calculation. Different assignments for some lines between Procyon and solar flare, have been found to be due to the hotter emitter in Sun than in Procyon coronae.

arXiv comment9 pages, 3 figures, Accepted by MNRAS

References in corpus (14)

• First Light Measurements with the XMM-Newton Reflection Grating Spectrometers: Evidence for an Inverse First Ionisation Potential Effect and Anomalous Ne A bundance in the Coronae of HR 1099
• First Light Measurements of Capella with the Low Energy Transmission Grating Spectrometer aboard the Chandra X-ray Observatory
• High Resolution X-Ray Spectra of Capella: Initial Results from the Chandra High Energy Transmission Grating Spectrometer
• High-resolution X-ray spectroscopy of Procyon by Chandra and XMM-Newton
• The Chandra Iron-L X-Ray Line Spectrum of Capella
• Helium-like triplet density diagnostics: Applications to CHANDRA--LETGS X-ray observations of Capella and Procyon
• 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
• The X-ray spectrum of Fe XVII revisited with a multi-ion model
• Chandra High-Resolution X-Ray Spectrum of Supernova Remnant 1E0102.2-7219
• Are stellar coronae optically thin in X-rays? - A systematic investigation of opacity effects
• Coronal density diagnostics with Si X: CHANDRA/LETGS observations of Procyon, $\alpha$ Cen A$&$B, Capella and $\epsilon$ Eri
• Electron impact collision strengths in Si IX, Si X and Si XI
• 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