61 Virginis

(The Planet Project)

61 Virginis has a remarkable three-planet system with a "super- earth" and two others similar in projected mass to Uranus or Neptune.


The circle shows the location of the sunlike class G6 star 61 Virginis (in the constellation Virgo) to the east of Corvus. Three planet are now known to orbit, at respective distances of 0.05, 0.22, and 0.48 Astronomical Units, with periods of 4.21, 38, and 123 days and masses of at least 5.1, 18.2, and 22.9 times that of the Earth. Note the especially small mass of the innermost planet. Orbital eccentricities are fairly low for the inner two at 12 and 14 percent, though that of the outer one is more than twice as great, which carries it between 0.94 and 0.31 AU from the star. Unfortunately, the planets do not transit the star, so the orbital tilts, and thus the actual masses, are not known.


61 Virginis is an easily-seen fifth magnitude (4.74) G6 (or G5) dwarf located at a precisely-known distance of 27.9 light years in southern Virgo to the east of Corvus with a surface temperature of 5560 Kelvin, just a bit cooler than that of the Sun. Its luminosity of 0.82 Suns gives a radius 0.98 solar, and suggests a mass 90 percent that of our own star, with an age that could be as high as 12 billion years. Other studies suggest a mass of 96 percent solar and a notably smaller age of 6 to 9 billion years, the star still clearly older than the Sun. Its metal content is normal. There is some evidence for a debris disk. The star's high velocity of 62 kilometers per second relative to the Sun suggests that it is a visitor from another part of the Galaxy. (Planetary and some stellar data from S. R. Vogt et al. in the Astrophysical Journal, vol, 708, p. 1366, 2010.)

70 Virginis also has a star with an orbiting planet.
Written by Jim Kaler. Return to The Planet Project or go to STARS.