ARCTURUS, the brightest star in the northern hemisphere, situated in the constellation Bootes in an almost direct line with the tail Q' and rt) of the constellation Ursa Major (Great Bear); hence its derivation from the Gr.
The Greeks identified this constellation with the nymph Callisto, placed in the heavens by Zeus in the form of a bear together with her son Arcas as " bear-warder," or Arcturus; they named it Arctos, the she-bear, Helice, from its turning round the pole-star.
Arcturus has been supposed to be referred to in various passages of the Hebrew Bible; the Vulgate reads Arcturus for stars mentioned in Job ix.
In addition to Arcturus, the brightest in the group, the most interesting stars of this constellation are: e Bootis, a beautiful double star composed of a yellow star of magnitude 3, and a blue star of magnitude 62; Bootis, a double star composed of a yellow star, magnitude 41, and a purple star, magnitude 61-; and W.
This constellation has been known by many other names - Arcas, Arctophylax, Arcturus minor, Bubuleus, Bubulus, Canis latrans, Clamator, Icarus, Lycaon, Philometus, Plaustri custos, Plorans, Thegnis, Vociferator; the Arabs termed it Aramech or Archamech; Hesychius named it Orion; Jules Schiller, St Sylvester; Schickard, Nimrod; and Weigelius, the Three Swedish Crowns.
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.
Then follows a gradual absorption of first the helium and then the hydrogen, the photosphere grows continually cooler, and the star passes successively through the stages exemplified by Sirius, Procyon, the Sun, Arcturus and Antares.
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.
Jacques Cassini also proved that Arcturus had even since the time of Tycho Brahe shifted five minutes in latitude; for r l Bootis, which would have shared in the change, if it had been due to a motion of the ecliptic, had not moved appreciably.
Probably the velocity of Arcturus is also over 100 m.
It is virtually identical with a group known as the " yellow stars," of which the most prominent examples are Capella, Pollux and Arcturus; this is not the most numerous group, however; more than one half of all the stars whose spectra are known belong to a simpler type in which the metallic lines are faint or absent, excepting hydrogen and sometimes helium, which declare themselves with increased prominence.
The Sumerians and Accadians, the non-Semitic inhabitants of the Euphrates valley prior to the Babylonians, described the stars collectively as a " heavenly flock "; the sun was the " old sheep "; the seven planets were the " old-sheep stars "; the whole of the stars had certain " shepherds, " and Sibzianna (which, according to Sayce and Bosanquet, is the modern Arcturus, the brightest star in the northern sky) was the " star of the shepherds of the heavenly herds."