New and improved experimental oscillator strengths in Zr II and the solar abundance of zirconium

Abstract

Using the Fourier Transform Spectrometer at Lund Observatory, intensity calibrated spectra of singly ionized zirconium have been recorded and analyzed. Oscillator strengths for 263 Zr ii spectral lines in the region 2500-5400 Å have been derived by combining new experimental branching fractions with previously measured radiative lifetimes. The transitions combine 34 odd parity levels with 29 low metastable levels between 0 and 2.4 eV. The experimental branching fractions have been compared with theoretical values and the oscillator strengths with previously published data when available. The oscillator strengths have been employed to derive the solar photospheric Zr abundance based on both 1D and 3D model atmospheres. Based on the seven best and least perturbed Zr ii lines in the solar disk-center spectrum, we determine the solar Zr abundance to log ε Zr = 2.58 ± 0.02 when using a 3D hydrodynamical solar model atmosphere. The new value is in excellent agreement with the meteoritic Zr abundance.

The solar photospheric abundance of zirconium

“…We compared the new log gf values determined by Ljung et al (2006) with those by Biemont et al (1981). There is a good agreement for most of the lines, with a few exceptions (see Table 2).…”

“…When we look only at the seven lines from Ljung et al (2006), we find that the line-to-line scatter is reduced with respect to the sample of 15 lines. The 3D abundance we find is 2.653 ± 0.022 and 2.623 ± 0.031 for disc-centre and disc-integrated data, respectively.…”

“…Gratton & Sneden (1994) used the same line list as Biemont et al (1981). Ljung et al (2006) derived new oscillator strengths for 263 Zr II lines and studied 7 lines, the lines that they judged to be the best and unperturbed in the photospheric spectrum, to derive the solar Zr abundance based on both 1D and 3D model atmospheres.…”

“…We picked up all the Zr II lines of Biemont et al (1981) and the line at 402.4 nm analysed in Ljung et al (2006). Our In addition, the equivalent width contribution functions (lower, roughly Gaussian-shaped curves) for the 405.0 nm Zr II line are plotted on the same optical depth scale for disc-centre (solid line) and disc-integrated spectra (dashed line).…”

“…After analysis, we discarded four other lines that also Biemont et al (1981) rejected because they provided a too high abundance. Our final sample is formed by the seven lines of Ljung et al (2006), that we discuss one by one in the next section, and 10 lines that are used for the abundance analysis in Biemont et al (1981).…”