Density sensitive C II lines in cool stars of low gravity

Measurements of radiative-decay rates of the 2s22p(2P°)-2s2Fang1, Kwong2, Wang3 et al. 1993Phys. Rev. A32081View full textAdd to dashboardCite

“…, the transition probabilities (A values), and thus the accuracies of the density and temperature diagnostic techniques depend strongly on the completeness and accuracy of the A-value data for the transitions involved. Until now, the A values for the lines of multiplet (UV 0.01) of C ii, N iii, and 0 iv were known only by theoretical means [12 -15] or, in the case of C ii, also by empirical estimates [10]. The present paper reports the first measurements of the values of the radiative lifetimes for the J = z,~, andl evels of the 2s2ps(4P) metastable term of C ii.…”

“…Because the rates for collisional excitation and deexcitation of ions in the diffuse atmospheres of these objects are comparable with the radiative-decay rates for intersystem and forbidden transitions, intensity ratios involving intersystem lines within the multiplet [9,10], or with forbidden or allowed lines [ll], can be applied to determine electron density and temperature.…”

Atomic data from the IRON Project

“…Zeippen A detailed table of the present transition probabilities is available in electronic form from the CDS via anonymous ftp 130.79.128.5 spectral lines are observed in a wide variety of astronomical sources where they are frequently used as temperature, density and abundance diagnostics (Peng & Pradhan 1995). For example, lines belonging to C II, N III and O IV have been identified in the spectrum of planetary nebulae (Stencel et al 1981), giant stars (Judge 1986a,b;Carpenter et al 1991), symbiotic stars (Nussbaumer & Schild 1981;Hayes & Nussbaumer 1986), in the solar chromosphere (Doschek et al 1977) and the solar transition region (Doschek et al 1976;Brekke et al 1991). Sandlin et al (1976) have observed the five components of the 2s 2 2p 2 P 0 − 2s2p 2 4 P multiplet of Fe XXII in solar-flare spectra.…”

PopRatio: A program to calculate atomic level populations in astrophysical plasmas

“…Intensities ratios of lines belonging to this multiplet may serve as a useful indicator of electronic densities in the range 10 7 ≤ n e ≤ 10 10 cm −3 [23,24]. These lines have been observed in the spectra of a variety of astronomical objects: planetary nebulae [25], giant stars [26,27], symbiotic stars [28] and in the solar chromosphere and transition region [29].…”