Of the first magnitude red stars Antares is the most deeply coloured, Betelgeux,.Aldebaran and Arcturus being successively less conspicuously red.
There is perhaps room for doubt as to the precise significance of the words used; but the fact that Ptolemy classes Sirius with Antares, Aldebaran, Arcturus, Betelgeux and Procyon as " fiery red " (inrorceppoc) as compared with all the other bright stars which are " yellow " (;av©oc) seems almost conclusive that Sirius was then a redstar.
Includes the " Solar " stars, as Capella, Arcturus, Procyon, Aldebaran, their spectra are similar to that of the sun, being crossed by very numerous fine lines, mostly due to vapours of metals.
From comparisons between the observed places of Arcturus, Aldebaran and Sirius and the places assigned to them by Alexandrian astronomers, he was led to the opinion that all three are moving towards the south (Phil.
Proctor found that between Aldebaran and the Pleiades most of the stars have a motion positive in right ascension and negative in declination, a phenomenon which he designated " star-drift."