科研之友
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摘要
We derive the abundance of 19 elements in a sample of 64 stars with fundamental parameters very similar to solar, which minimizes the impact of systematic errors in our spectroscopic 1D-LTE differential analysis, using high-resolution (R similar or equal to 60 000), high signalto- noise ratio (S/N similar or equal to 200) spectra. The estimated errors in the elemental abundances relative to solar are as small as similar or equal to 0.025 dex. The abundance ratios [X/Fe] as a function of [Fe/H] agree closely with previously established patterns of Galactic thin-disk chemical evolution. Interestingly, the majority of our stars show a significant correlation between [X/Fe] and condensation temperature (T(C)). In the sample of 22 stars with parameters closest to solar, we find that, on average, low T(C) elements are depleted with respect to high T(C) elements in the solar twins relative to the Sun by about 0.08 dex (similar or equal to 20%). An increasing trend is observed for the abundances as a function of T(C) for 900 < T(C) < 1800K, while abundances of lower T(C) elements appear to be roughly constant. We speculate that this is a signature of the planet formation that occurred around the Sun but not in the majority of solar twins. If this hypothesis is correct, stars with planetary systems like ours, although rare (frequency of similar or equal to 15%), may be identified through a very detailed inspection of the chemical compositions of their host stars.
- 出版日期2009-12
