Jacobi coordinates are R=m1Mx1+m2Mx2{\displaystyle {\boldsymbol {R}}={\frac {m_{1}}{M}}{\boldsymbol {x}}_{1}+{\frac {m_{2}}{M}}{\boldsymbol {x}}_{2}} and r=x1−x2{\displaystyle {\boldsymbol {r}}={\boldsymbol {x}}_{1}-{\boldsymbol {x}}_{2}} with M=m1+m2 {\displaystyle M=m_{1}+m_{2}\ }
Own work
CWitte, from JPG by Brews ohare