set term   pdf
set out    "plot.pdf"
set title  "equatorial motion of a planet around a star"
set xlabel "x"
set ylabel "y"
set grid
set key left
plot \
 "data" using (1/$2)*sin($1):(1/$2)*cos($1) with lines notitle \
,"-" with points pt 5 title "star"
0 0
e