documentclass{standalone}
usepackage{tikz}
usetikzlibrary{positioning}
begin{document}
begin{tikzpicture}
node [align=left] (first) {long text\ $S_{000}$};
node [below=1em of first, align=left] (second) {long text\ $S_{ttt}$};
node [below=1em of second, align=right] (third) {long text\ $S_{000}$};
node [below=1em of third, align=right] (fourth) {long text\ $S_{ttt}$};
end{tikzpicture}
end{document}