Adhil

A faint star that lies on the fringes of the Milky Way as it passes across the northern edge of Andromeda. Despite a magnitude of just +4.9, placing it barely on the limits of naked eye visibility, this star carries the traditional proper name of Adhil, from the Arabic for 'train' or 'tail'. This is usually taken to refer to the train of Andromeda's robe, though in its literal sense of 'tail' it may go back to an older Arabic tradition of seeing the stars of central Andromeda as a southward-swimming fish (Adhil and its flanking stars Phi and Omega Andromedae do indeed form something like the shallow 'V' of a fish's tail).

Adhil is a giant orange star some fifteen times the diameter of the Sun, belonging to a branch of stars known as the 'red clump'. Stars of this kind have consumed the hyrdrogen in their cores, and now shine by fusing helium into carbon and oxygen. A notable feature of these red clump stars is the fact that they shine with a closely consistent luminosity, making precise calculations of their distance possible. From the absolute magnitude of Adhil, +0.77, it is therefore possible to determine its distance with considerable confidence: it lies some 223 light years (or 68.5 parsecs) from the Solar System.