Eta Virginis

Eta Virginis (η Vir, η Virginis) is a multiple star system in the zodiac constellation of Virgo. It has the traditional name Zaniah /zəˈnaɪ.ə/. From parallax measurements, the distance to this star was found to be roughly 265 light-years (81 parsecs). It has an apparent visual magnitude of 3.89, which is bright enough for the system to be seen with the naked eye in dark skies.

Although the star looks single in any telescope, lunar occultations have shown this star to be a very close triple star system consisting of two stars only 0.5 AU apart with a third slightly more distant star. The inner pair is a spectroscopic binary that completes an orbit with a period of 72 days. The inclination of this orbit was determined through interferometer observations to be 45.5°, which allowed the individual masses of the two stars to be estimated. The primary star, η Vir Aa, has a mass of about 2.5 times the Sun's mass, while the secondary, η Vir Ab, has 1.9 solar masses. The faint tertiary star, η Vir B, orbits the inner group in a wider orbit over a period of 13.1 years.

Because Zaniah is near the ecliptic, it can be occulted by the Moon and (very rarely) by planets. On October 12, 272 BC, the ancient Greek astronomer Timocharis observed a conjunction of the star with Venus. The last occultation by a planet took place on September 27, 1843, also by Venus, which will occult it again on November 19, 2445.