Nu³ Canis Majoris

Southwestward from Sirius in Canis Major lies an elongated triangle of relatively faint stars, all designated Nu Canis Majoris. Nu³ Canis Majoris is the northernmost of these three, and appears closest to Sirius in the sky. Though the three stars lie on a very approximate line of sight from Earth, they are entirely unrelated, and lie a considerable distance apart from one another in space.

Nu³ is the most distant of these three stars. It was formerly estimated to be some 420 light years from the Sun, but the recent GAIA measurements suggest that it is actually somewhat farther away, at a distance of some 479 light years. (By comparison, the nearest of the three 'Nu' stars, Nu² Canis Majoris, lies just 64 light years from the Solar System, roughly one quarter of the distance to Nu³.)

This is a binary system, of which the primary star is an orange giant (more precisely, lies on the border between giants and the more luminous class of stars known as bright giants). It has a diameter some thirty times that of the Sun, and generates several hundred times as much light energy. This massive star has a companion in orbit, designated Nu³ Canis Majoris B.