A Differential Abundance Analysis of the Wide Binary Pair HD 219542 A and B

Abstract

The abundances of 22 elements (Li through Zr) in the A and B components of the visual pair HD 219542 were determined and compared using a differential analysis technique. Both components were found to be metal rich, $[\mathrm{Fe/H}] = +0.13$, in the brighter component (A) and $[\mathrm{Fe/H}] = +0.08$ in the fainter component (B). The abundances of three elements (Sc, Ti, and Fe) are definitely higher (by 0.05 dex) in component A than in component B. On the other hand, both components have nearly identical abundances of the light element Si. No evidence has been found for differences in the abundances for C, O, Na, Mg, Al, S, Ca, V, Cr, Mn, Co, Ni, Cu, Zn, Sr, Y, and Zr. No clear correlation has been found between the differences in the abundance between the two components and the condensation temperature ($T_\mathrm{c}$).

Abundance difference between components of wide binaries

“…They found (T eff , log g, ξ, 5830, 4.45, 0.95, 0.13) and (5600, 4.40, 0.90, 0.08) for HD 219542A and B respectively. Our parameters for the primary are fairly similar to their values, while their temperature differences is larger by 62 K. However, we note that the statistical error quoted by Sadakane et al (2003) for the temperature difference is 42 K (30 K for each star). Furthermore, we note some inconsistencies in the parameters they derived.…”

“…As a check that the discrepancy is not due to EW measurements, we analyzed our data using the Sadakane et al (2003) atmospheric parameters, and found very similar abundance differences than obtained by them, and the Sadakane et al (2003) EW using our technique. The latter test gives a temperature difference 27 K larger than ours (195 vs. 168 K) and an abundance difference of 0.012 dex.…”

“…The continuum level and the EWs were re-measured on the same spectra of Paper I to be fully consistent with the other stars studied in this paper, but without significant differences in the EWs with respect to Paper I. We also compared our EWs with those of Sadakane et al (2003). We obtain a mean difference of −0.050 ± 0.074 mÅ and −0.051 ± 0.069 mÅ with an rms of 3.65 and 3.36 mÅ (24 lines) for HD 219542A and B respectively.…”

“…We also compared our results with those of Sadakane et al (2003). They used spectra with a higher signal to noise ratio than ours (about 500) but measured a lower number of spectral lines (46 Fe I and 7 Fe II lines respectively).…”

Precise Differential Analysis of Stellar Metallicities: Application to Solar Analogs Including 16 Cyg A and B

“…Such a slightly metal-rich nature of HD 219542 A compared to B has also recently been confirmed by Sadakane et al (2003), who concluded [Fe/H] A − [Fe/H] B = + 0.05 dex. From a quantitative point of view, however, the extent of the difference is discrepant ( + 0.09 and + 0.05) between these two studies, and the discordance is larger than their estimated errors, 2 which makes us wonder which is more reliable and whether an accuracy on the order of 2 Although Sadakane et al (2003) presented only the standard deviation values and did not discuss in sufficient detail about the error involved in the mean difference of + 0.05 dex they derived, the random error for the mean abundance difference from Fe I lines may be estimated as σ √ N = 0.032/ √ 46 0.005, which is comparable to that of Gratton et al (2001) (i.e., pure random error of 0.006 without including the effect of parameter uncertainties). However, the actual uncertainties may be much larger, when ambiguities in the atmospheric parameters are taken into account, as discussed in section 5.…”