Denebola

Denebola is Beta Leonis, apparent magnitude 2.11, at roughly 36 light years. It is a white main-sequence star, type A3, rotating rapidly and slightly variable, and it is young enough to retain a disc of debris detectable in the infrared, a system perhaps still forming or clearing planets. The Arabic name, from dhanab al-asad, means simply the tail of the lion, its position in the figure. It marks the eastern end of Leo, opposite the bright Regulus at the heart.

The debris disc around Denebola, detected through excess infrared radiation the dust re-emits after absorbing the star's light, marks it as a young system still possibly shedding material left over from planet formation; at only thirty-six light years it is close enough that the disc has been a useful nearby laboratory for studying how such systems evolve. Denebola's youth and rapid rotation together make it a star still settling into stable adulthood by stellar standards, a useful nearby example for astronomers studying how debris discs and planetary systems evolve around A-type stars generally. Denebola's proximity, among the nearer bright stars in this entire set of tables, makes its debris disc an unusually well-studied nearby example of the type.

Sources AstronomyAndrew Fraknoi, David Morrison, and Sidney C. Wolff (OpenStax) with Almagest (Mathematike Syntaxis)Claudius Ptolemy

Ptolemy gives the star in the lion's tail the nature of Saturn with Venus, and the later tradition turned this into one of the more ill-omened delineations in the catalogue: Robson reads Denebola for misfortune, disgrace, regret and reversal, and older Arabic material associated the region with sudden calamity. The chain from a bare Ptolemaic pairing to a full sentence of doom is the standard pattern with this material, and the doom is mostly late. The star itself is unremarkable in reputation's sense and remarkable in fact, a nearby, young, dusty A-type star of exactly the kind now searched for planets.

That Denebola's harsh reputation is "mostly late" can be checked directly against Ptolemy's own wording, which assigns Leo's stars a Saturn-and-Venus nature in general terms without singling out the tail star for any of the specific disasters, disgrace, or reversal that the Victorian compilers later attached to it by name. Robson's specific wording for Denebola draws heavily on earlier nineteenth-century compilations by authors such as Ebertin and the older Arabic-derived lists translated into English during the same period, part of the same broad chain of transmission visible throughout this catalogue.