Implications of the spectroscopic abundances in α Centauri A and B

Abstract

Regardless of their close proximity, abundance measurements for both stars in α Centauri by different groups have led to varying results. We have chosen to combine the abundance ratios from five similar data sets in order to reduce systematic effects that may have caused inconsistencies. With these collated relative abundance measurements, we find that the α Cen system and the Sun were likely formed from the same material, despite the [Fe/H] enrichment observed in the α Cen binaries: 0.28 and 0.31 dex, respectively. Both α Centauri A and B exhibit relative abundance ratios that are generally solar, with the mean at 0.002 and 0.03 dex, respectively. The refractory elements (condensation temperature ≳ 900 K) in each have a mean of −0.02 and 0.01 dex and a 1σ uncertainty of 0.09 and 0.11 dex, respectively. Given the trends seen when analysing the refractory abundances [X/Fe] with condensation temperature, we find it possible that α Centauri A may host a yet undiscovered planet.

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