(both stars that are fascinating variable stars and colorful doubles).
These 'classical doubles', as I would describe them, often consist of reddish primaries accompanied by bluish-green companions, of which Albireo (Beta Cygni), Almaach (Gamma Andromedae), Rasalgethi
(Alpha Herculis) and 95 Herculis are prominent examples.
It contains a red giant variable star named Rasalgethi
which varies in brightness but also has a blue companion so is a double star as well.
Now we'll head over to Hercules where we'll meet the spectacular double Alpha ([alpha]) Herculis, Rasalgethi
, Hercules' brightest star, lies quite close to Rasalhague.
Indeed, in the early 3rd millennium BC when the north celestial pole was near Alpha Draconis, if you looked high in the north from Mesopotamian latitudes when the Kneeler's head (Alpha Herculis, Rasalgethi
) was near the zenith, you would have seen Draco curved out beneath his feet.
The proper name for Alpha Herculis is Rasalgethi
, which as a child learning the stars I pronounced rass-AL-guh-thi.
Hercules 3.5 5.4 Rasalgethi
. A little globe touching a bright red star, breathtaking!
Alpha ([alpha]) Herculis, also called Rasalgethi
, is a much easier supergiant double to split.
Third, Rey ignored the ancient, millennially accepted constellation figures--which remain on classical maps, in legendry, and in Arabicized star names everywhere: the Head of the Kneeler (Rasalgethi
), the Tail of the Sea Monster (Deneb Kaitos).
You could begin with Albireo (Beta Cygni) and Rasalgethi
(Alpha Herculis), two of the color-contrast pairs that are very high in this sky.
It must compete with the intensely hued showpiece double Rasalgethi
(Alpha Herculis) and the magnificent Hercules Cluster (Messier 13).