2001A&A...376.1113P


C.D.S. - SIMBAD4 rel 1.7 - 2021.04.19CEST11:00:08

2001A&A...376.1113P - Astronomy and Astrophysics, volume 376, 1113-1122 (2001/9-4)

Line ratios for helium-like ions: Applications to collision-dominated plasmas.

PORQUET D., MEWE R., DUBAU J., RAASSEN A.J.J. and KAASTRA J.S.

Abstract (from CDS):

The line ratios R and G of the three main lines of He-like ions (triplet: resonance, intercombination, forbidden lines) are calculated for CV, NVI, OVII, NeIX, MgXI, and SiXIII. These ratios can be used to derive electron density ne and temperature Te of hot late-type stellar coronae and O, B stars from high-resolution spectra obtained with Chandra (LETGS, HETGS) and XMM-Newton (RGS). All excitation and radiative processes between the levels and the effect of upper-level cascades from collisional electronic excitation and from dielectronic and radiative recombination have been considered. When possible the best experimental values for radiative transition probabilities are used. For the higher-Z ions (i.e. NeIX, MgXI, SiXIII) possible contributions from blended dielectronic satellite lines to each line of the triplets were included in the calculations of the line ratios R and G for four specific spectral resolutions: RGS, LETGS, HETGS-MEG, HETGS-HEG. The influence of an external stellar radiation field on the coupling of the 23S (upper level of the forbidden line) and 23P levels (upper levels of the intercombination lines) is taken into account. This process is mainly important for the lower-Z ions (i.e. CV, NVI, OVII) at moderate radiation temperature (Trad). These improved calculations were done for plasmas in collisional ionization equilibrium, but will be later extended to photo-ionized plasmas and to transient ionization plasmas. The values for R and G are given in extensive tables, for a large range of parameters, which could be used directly to compare to the observations.

Abstract Copyright:

Journal keyword(s): X-rays: stars - atomic processes - stars: coronae - stars: late-type - stars: activity - early-type stars: activity

VizieR on-line data: <Available at CDS (J/A+A/376/1113): gline.dat rline.dat taba1-3.dat taba4-6.dat>

Simbad objects: 8

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Number of rows : 8

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 * alf Aur SB* 05 16 41.35871 +45 59 52.7693 1.33 0.88 0.08 -0.52 -0.96 G3III: 1146 0
2 Mrk 3 Sy2 06 15 36.458 +71 02 15.24 14.21 14.03 12.97     ~ 862 3
3 * alf CMi SB* 07 39 18.11950 +05 13 29.9552 0.82 0.79 0.37 -0.05 -0.28 F5IV-V+DQZ 1781 0
4 * zet Pup BY* 08 03 35.04754 -40 00 11.3321 0.89 1.98 2.25 2.36 2.58 O4I(n)fp 1108 1
5 NGC 4051 Sy1 12 03 09.6098828919 +44 31 52.693714606   11.08 12.92 9.94   ~ 2035 1
6 NGC 4151 Sy1 12 10 32.5771747733 +39 24 21.057727323   12.18 11.48     ~ 3442 2
7 NGC 5548 Sy1 14 17 59.5401093128 +25 08 12.600227883   14.35 13.73     ~ 2451 0
8 * alf Cen ** 14 39 29.71993 -60 49 55.9990   0.4 -0.1     G2V+K1V 850 0

    Equat.    Gal    SGal    Ecl

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2021.04.19-11:00:08

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