Adhab

Adhab is one of the small stars of Andromeda that carry an Arabic-derived name in the astrological catalogues without any accompanying interpretive tradition. Andromeda in the Greek scheme is the daughter of Cepheus and Cassiopeia, chained to the rock in expiation of her mother's boast and rescued by Perseus, and the constellation shares its brightest star, Alpheratz, with the Great Square of Pegasus. Only three or four stars of the figure, Alpheratz, Mirach and Almach, carry any settled traditional meaning; the rest, this one among them, appear in the lists as positions with names attached. Ptolemy assigned planetary natures only to the stars he thought worth describing, and where he is silent later astrology has generally either left the star alone or filled the gap by inference from the constellation as a whole, which is a much weaker basis.

That only Alpheratz, Mirach and Almach among Andromeda's stars carry any real weight in the tradition while the rest, Adhab included, sit unread is not unusual for a Ptolemaic-era constellation; the ancient magnitude catalogues generally recorded only a figure's brightest handful of stars with any care, and later compilers filling out a full constellation list for astrological use had comparatively bare source material to draw on for everything fainter.

The atlas records this star at Taurus 10 degrees 29 minutes, projected from a position in Andromeda well north of the ecliptic.

That figure is shared. Adhil is recorded at exactly the same sign, degree and minute, in the same constellation, and two distinct stars agreeing to the arcminute is not something that happens by chance in a list of fifty seven. The two entries are one star, entered twice under two spellings of a name, and the two records agreeing to the arcminute is what shows it. This is an ordinary hazard of the modern fixed-star lists, which were assembled by successive compilers copying one another and absorbing variant transliterations of the same Arabic name as though they were separate objects.

On precession, the longitude is a dated quantity: a fixed star gains about fifty seconds of arc a year, one degree in roughly seventy two years. Taking the value for epoch 2000, the star entered Taurus in the middle of the thirteenth century and will reach Gemini in about fourteen hundred years.

Neither the duplication nor the drift is a defect in the record so much as a property of it, and both are worth knowing before the entry is used.