method  number  orbital_period   mass  distance  year
0  Radial Velocity       1          269.30   7.10     77.40  2006
2  Radial Velocity       1          763.00   2.60     19.84  2011
3  Radial Velocity       1          326.03  19.40    110.62  2007
6  Radial Velocity       1         1773.40   4.64     18.15  2002
7  Radial Velocity       1          798.50    NaN     21.41  1996