The $6563 A^{\circ} H_2$ line emitted by hydrogen in a star is found to be red shifted by $15^{\circ}$ , Estimate the speed with which the star is reading from earth .

Question

$\begin{array}{1 1} 6.86 \times 10^{5} ms^{-1} \\ 6.86 \times 10^{6} ms^{-1} \\ - 6.86 \times 10^{5} ms^{-1} \\ -6.86 \times 10^{6} ms^{-1} \end{array} $