Galactic chemical evolution of the solar neighborhood, solar twins and exoplanet indicators

Galactic chemical evolution (GCE), solar analogues or twins, and peculiarities of<br> the solar composition with respect to the twins are inextricably related.<br> We examine GCE parameters from the literature and present newly derived values<br> using a quadratic fit that gives zero for a Solar age (i.e. 4.6 Gyr). <br> We show how the GCE parameters may be used not only to ``correct'' abundances<br> to the solar age, but to predict {\bf average} relative elemental <br> abundances as a function of age. <br> We address the question of whether the solar abundances<br> are depleted in refractories and enhanced in volatiles and<br> find that the answer is sensitive to the selection of a<br> representative standard. Our best quality data sets do<br> not support the notion that the Sun is depleted in refractories. <br> A simple model allows us to estimate<br> the amount of refractory-rich material missing from the sun<br> or alternately added to the average solar twin. The model<br> gives between zero and 1.4 earth masses. <br>