2008/03/14 by G. Y. Liang, Guiyun Liang, Gang Zhao
Physics and Astronomy · #Atomic and Molecular Physics #Solar and Space Plasma Dynamics #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1088/0004-6256/135/6/2291
15 pagess, 5 figures and 4 tables, accepted for publication on AJ
arxiv created 2008/03/14 · openalex publication_date 2008/05/13 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/31
A line ratio of 3d–2p transition lines in boron-like spectra of Si x , S xii , Ar xiv , and Fe xxii has been investigated. Collisional-radiative model calculations reveal that the line ratio is sensitive to the electron density in ranges of n e = 4.0 × 10 7 –3.0 × 10 10 cm −3 , 4.0 × 10 8 –3.0 × 10 11 cm −3 , 3.0 × 10 9 –4.0 × 10 12 cm −3 , and 2.0 × 10 12 –3.0 × 10 15 cm −3 , respectively. This complements the K-shell diagnostics of helium-like ions. By a comparison between the predicted and the measured values, effective electron densities in the electron beam ion trap (EBIT) plasmas, performed by Lepson and collaborators at the Lawrence Livermore EBIT, are estimated to be n e = 3.4 +0.8 −0.6 × 10 10 cm −3 and 5.6 +1.0 −1.1 × 10 10 cm −3 for sulfur and argon plasmas, respectively. In the case of argon, a good agreement is shown with the actual electron density derived from an N vi K-shell spectrum. We further explore the 3d–2p transition lines of Si x and S xii in the stellar coronal spectra measured with the low energy transmission grating spectrometer combined with a high resolution camera on board the Chandra X-Ray Observatory . The constrained electron densities show a good agreement with those determined from C v and O vii K-shell spectra.