Linear regression fit coefficients

During their final stages of evolution, stars experience nucleosynthesis several times, each at different timescales and producing different chemical elements. Finding abundance ratios that have simple variations across cosmic times therefore remains a challenge.

Using the sample of 80 solar twins for which ages and abundances of 30 elements have been measured with high precision, we searched for all possible abundance ratio combinations that show linear trends with age. We found 55 such ratios, all combining an n-capture element and another element produced by different nucleosynthesis channels. We recovered the ratios of [Y/Mg], [Ba/Mg], and [Al/Y] that have been reported previously in the literature, and found that [C/Ba] depends most strongly on age, with a slope of 0.049+/-0.003dex/Gyr.