Astronomy & Astrophysics

All Tables

Table 1: The configurations used to calculate the radiative data.
Table 2: Energy levels for the main three configurations in Fe XII, plus a few significant ones from the 3s 3p³ 3d configuration. The percentage of level mixing (>10%) is indicated in second column. $E_{\rm best}$ indicates the best energies (cm^-1) which we propose in this work. The uncertainties in the energies reflect the estimated errors in the wavelength measurements. Levels with uncertain identification are assigned an uncertainty of 500 cm^-1. The following columns indicate the differences between our $E_{\rm best}$ and the energies from NIST $E_{\rm NIST}$ , the collisional calculations $E_{\rm CC}$ , and the adjusted SS values $E_{\rm SS}$ . Levels are ordered according to the energies $E_{\rm CC}$ from the collisional calculations.
Table 3: Results for the brightest lines in Fe XII. The lines are grouped in different transition arrays, and are displayed in decreasing order of intensity. Columns 2, 3 show the relative line intensities (photons) $Int=N_{j} A_{ji}/N_{\rm e}$ calculated at log T[K] = 6.15 and 10⁸, 10¹² cm^-3, normalised to the intensity of the brightest line. Columns 4, 5 show the gf and A values calculated in this work. Column 6 shows, for comparison, the NIST A values. The last two columns show the wavelengths corresponding to the best energies $E_{\rm best}$ of Table 2 and the NIST vacuum wavelengths. The uncertainties on the proposed wavelengths are derived from the uncertainties assigned to the energies.
Table 4: Measured and predicted lifetimes for some of the levels in Fe XII. Measured values from M01: Moehs et al. (2001); T02: Träbert et al. (2002). The predicted values have been calculated here with SUPERSTRUCTURE and adjusted energies. Note the excellent agreement.
Table 5: Summary of the line identifications for Fe XII. The columns indicate: 1) the indices corresponding to Table 2; 2) the relative intensity (at 10⁸, 10¹² cm^-3, and log T[K] = 6.15), scaled to the brightest line; 3) the wavelengths calculated from our best energies $E_{\rm best}$ ; 4) observed wavelengths $\lambda _{\rm observed}$ (unless specified otherwise values are from Behring et al. 1976); some details are indicated (bl = blend; bl-mr = blend in medium-resolution spectra; bl-w = blend with a weak line; U = previously unpublished); lines with no or a tentative identification have a question mark; 5 and 6) previous original identifications consistent or not with ours (with observed wavelengths in Å; note that observed and calculated wavelengths in the cited literature can differ from the values reported here). The last column indicates new (N) or revised (R) identifications, and if a spectral line is only visible in high-density plasmas (H). Legenda: BRW67: Burton et al. (1967); B78: Bromage et al. (1978); D99: Del Zanna (1999); F67: Fawcett et al. (1967); F70: Fawcett (1970); F71: Fawcett (1971); G66: Gabriel et al. (1966); G71: Gabriel et al. (1971); Je71: Jefferies et al. (1971); J71: Jordan (1971); J93: Jupen et al. (1993); S71: Svensson (1971); SBT77: Sandlin et al. (1977); T98: Trabert (1998).
Table 6: Intensity ratios (ergs) of the 1242 and 1349.4 Å lines and electron densities $N_{\rm e}$ (cm^-3) for different sources. SBT77: Skylab NRL-ATM off-limb observations reported by Sandlin et al. (1977); FD77: Skylab NRL-ATM off-limb observations reported by Feldman & Doschek (1977); VR78: Skylab Harvard-ATM off-limb observations reported by Vernazza & Reeves (1978); S86: HRTS and Skylab NRL-ATM observations of an active region (plage), a sunspot (umbra) and at the solar limb, reported by Sandlin et al. (1986); C94: active regions (AR) and flare on-disc/limb observations with the Skylab NRL-ATM reported by Cook et al. (1994); S: SOHO/SUMER off-limb observations (see text); J01: HST/STIS stellar observations reported by Jordan et al. (2001).