Epsilon Librae

A faint fifth-magnitude star in the north central parts of the constellation Libra, Epsilon Librae lies some two degrees southeastward of the brighter blue star Zubeneschemali. This is a binary system some 94 light years from the Sun, in which a hot bright yellow star (Epsilon Librae A) is closely orbited by a much less massive dwarf (Epsilon Librae B). The dwarf's 227-day orbit has a semi-major axis of 0.85 AU and is significantly eccentric - compared against the orbits of planets in Solar System, Epsilon Librae B at times approaches its primary more closely than Mercury, and at times strays as far out as the orbit of Mars.

The primary Epsilon Librae A is a bright yellow F-type star, rather hotter and more massive than the Sun. Its diameter is estimated as more than twice the Sun's, and it is some nine times as luminous. This is an old star, close to the end of the its hydrogen-burning phase, and is variously categorised as a main-sequence star or a subgiant. By contrast, its companion Epsilon Librae B is much less massive than the primary, and is estimated to have less than half the mass of the Sun.