61 Vir and Its Three Planets

61 Vir is a G-type dwarf 27.7 light-years away, and its spectral type G5V marks it as Sun-like. The star is 8.96 billion years old, holds 0.94 solar masses, spans 0.98 solar radii, and has a temperature of 5570 K. Its reported mass and radius estimates are smaller than the Sun's, and its reported temperature is cooler than the Sun's. Three planets are known to orbit this host.

All three were found by the radial velocity method, which measures the wobble a planet's gravity induces in its star's motion; repeating wobbles reveal the planet and its orbital period. 61 Vir b, discovered in 2009, has a minimum mass of 5.1 Earth masses, larger than Earth's, and an orbital period of 4.22 days, the shortest among the listed planets.

61 Vir c, also discovered in 2009, has a minimum mass of 18.2 Earth masses, larger than Earth's, and an orbital period of 38 days, the second-shortest among the listed planets. 61 Vir d, likewise discovered in 2009, has a minimum mass of 22.9 Earth masses, larger than Earth's, and an orbital period of 123 days, the longest among the listed planets. Among the listed planets, 61 Vir b has the smallest minimum mass, 61 Vir c the second-smallest minimum mass, and 61 Vir d the largest minimum mass. Each of these minimum masses is a lower bound on the planet's true mass.