Issue |
A&A
Volume 499, Number 3, June I 2009
|
|
---|---|---|
Page(s) | 943 - 954 | |
Section | Atomic, molecular, and nuclear data | |
DOI | https://doi.org/10.1051/0004-6361/200811423 | |
Published online | 16 April 2009 |
R-matrix electron-impact excitation data for B-like Si and its application in cool stars
Department of Physics, University of Strathclyde, Glasgow, G4 0NG, UK e-mail: guiyun.liang@strath.ac.uk
Received:
26
November
2008
Accepted:
2
April
2009
We present the results of an intermediate coupling frame-transformation R-matrix calculation for the electron-impact excitation of Si9+. The target and close-coupling expansions are both taken to be the 125 fine-structure levels (58 LS terms) belonging to the
configurations 2sx2py () and 2s
2p
3l (α+β = 2, l = s, p, and d). Due to the additional resonances included in our calculation, we find significant differences at low temperatures with the widely used n = 2
2 excitation rates, also obtained with the R-matrix method, as well as with the n = 2
3 excitation
rates calculated by using the distorted wave (DW) approximation.
We present a list of prominent transition lines and comparisons with SERTS and Hinode/EIS EUV spectra of the solar corona, SUMER observations for the quiet sun, as well as Chandra LETG and
Rocket soft X-ray spectra of the Procyon corona and solar flares, respectively. Line emissivities of some transitions are enhanced up to 40% when compared with those obtained from using the
previous atomic data at the same electron density (1.6
109 cm-3) and temperature (1.3
106 K). The comparison with Chandra LETG observation of Procyon reveals that the 3s-2p line flux was significantly underestimated (by a factor of 4-5) in previous analyses. Some EUV and soft X-ray emission line ratios are
-sensitive and
-insensitive. Estimated electron densities from them shift downwards due to the new resonant-enhanced excitation data used in the present modelling.
Key words: atomic data / atomic processes / plasmas / stars: coronae / X-rays: stars / ultraviolet: solar system
© ESO, 2009
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.