61 Virginis

Primary of Nahelennia.

61 Virginis (abbreviated 61 Vir) is a G5V class star slightly less massive than the Sun (G2V), located about 27.8 light-years away in the constellation of Virgo. The composition of this star is nearly identical to the Sun and there is only a low level of activity in the stellar chromosphere.

This star is rotating once every 29 days at the equator. The space velocity components of this star are U = –37.9, V = –35.3 and W = –24.7 km/s. 61 Vir is orbiting through the Milky Way galaxy at a distance of 6.9 kpc from the core, with an eccentricity of 0.15. It is believed to be a disk star with an estimated age of more than six billion years.

There was some evidence that it may have a jovian planet, but it seemed not to have a nearby massive companion. A subsequent study also failed to find the large substellar companion (with 20 to 80 times the mass of Jupiter) or a Jupiter-class planet, so it was a good candidate for possessing a family of terrestrial planets, with an orbit slightly smaller and a year slightly less than that of the Earth.

A survey of this star with the Spitzer Space Telescope revealed an excess of infrared radiation at a wavelength of 160 μm. This indicated the presence of a debris disk in orbit around the star. This disk was resolved at 70 μm, corresponding to an inner radius of 96 AU from the star. The outer radius is estimated as 195 AU and the total mass of the disk is 5 × 10−5 the mass of the Earth.

On 14 December 2009, scientists announced the discovery of three planets with masses between 5 and 25 times that of Earth orbiting around 61 Virginis. The three planets all orbit very near the star; when compared to the orbits of the planets in our solar system, all three would orbit inside the orbit of Venus. Additional data is needed to confirm the possibility of a fourth planet, although an Earth-mass planet in the star's habitable zone (which would still be too small to detect with current technology) remains possible.