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 Chandra Public Data Archive were co‐added and analysed. 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.. Using the emission measure derived by Raassen et al., 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 emission lines are identified first 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 Å to Si x (52.612 Å ), at 69.641 Å to the blending of Si vii (69.632 Å) and Si viii (69.664 Å) lines, as well as at 70.050 Å to Si vii (70.027 Å). The prediction reveals the large discrepancies between the 3s–2p line (63.715 Å) and 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.

R -MATRIX ELECTRON-IMPACT EXCITATION OF Fe 13+ AND ITS APPLICATION TO THE SOFT X-RAY AND EXTREME-ULTRAVIOLET SPECTROSCOPY OF CORONA-LIKE PLASMAS

“…In the present work, we extract the line flux as done in the work of Liang & Zhao (2008) at the wavelengths as listed in Table 4. Table 4 Prominent Soft X-ray Lines and their Intensity Ratios (Relative to that of the Line at 58.963 Å) Recorded in Solar (Acton et al 1985) and Procyon (Raassen et al 2002) Because of low count rates in the Procyon observations, errors are found to be relatively large.…”

Radiative decay probabilities of the(2s22p1/253s1/

“…Although FAC was developed only rather recently, it has already been used extensively for the calculation of atomic data [34][35][36]. The recent measurement of the radiative decay rate of the (2s 2 2p 5 3/2 3s 1/2 ) J =2 level [24] provided a first test of FAC calculations of radiative rates, and excellent agreement between the calculated value of 2.06 × 10 5 s −1 and the measured value of (2.04 +0.03 −0.09 ) × 10 5 s −1 was found.…”