Open AccessElectron density diagnostic potential of the Si x ion and its application in Procyon
Author(s) -
Liang G. Y.,
Zhao G.,
Shi J. R.
Publication year - 2006
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2006.10090.x
Subject(s) - physics , electron density , atomic physics , electron , line (geometry) , ion , electron temperature , excitation , emission spectrum , spectral line , geometry , mathematics , quantum mechanics , astronomy
ABSTRACT Theoretical electron density sensitive line ratios R 1 – R 6 of Si x soft X‐ray emission lines are presented. We found that these line ratios are sensitive to electron density n e , and the ratio R 1 is insensitive to electron temperature T e . For reliable determination of the electron density of laboratory and astrophysical plasmas, atomic data, such as electron impact excitation rates, are very important. Our results reveal that the discrepancy of the line ratios from different atomic data calculated with the distorted wave (DW) approximation and the R‐matrix method is up to 19 per cent at n e = 2 × 10 8 cm −3 . We applied the theoretical intensity ratio R 1 to the Low Energy Transmission Grating Spectrometer (LETGS) spectrum of the solar‐like star Procyon. By comparing the observed value (1.29) with the theoretical calculation, the derived electron density n e is 2.6 × 10 8 cm −3 , which is consistent with that derived from (C v < 8.3 × 10 8 cm −3 ) . When the temperature structure of the Procyon corona is taken into account, the derived electron density increases from n e = 2.6 × 10 8 to 2.8 × 10 8 cm −3 .