Rasalgethi

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Rasalgethi

(ras-al-jee -th'ee) (α Her) A visual binary in the constellation Hercules. The primary (A) is a red supergiant that varies irregularly in magnitude from 2.7 to 4.0, the 5th-magnitude yellow giant companion (B) appearing green by contrast. B is a spectroscopic binary, period 51.6 days. Spectral type: M5 I (A), G5 III + F2 (B); distance: 193 pc.
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Caption: The multiple-star system Alpha Herculis, popularly known as Rasalgethi, marks the head of Hercules, who kneels upside down in our night sky.
Caption: HERCULES The color contrast makes Alpha Herculis an attractive split.
Near it is the dimmer head of Hercules: Alpha Herculis or Rasalgethi--a fine orange-and-yellow telescopic double star.
I drew up a double-star list and one by one began to bag its targets: Alpha Ursae Majoris, Epsilon Bootis, Alpha Canum Venaticorum, Gamma Leonis, Beta Cygni, Alpha Herculis, Epsilon Lyrae.
The proper name for Alpha Herculis is Rasalgethi, which as a child learning the stars I pronounced rass-AL-guh-thi.
In fact, Alpha Herculis is at the lower end of the supergiant class, sometimes categorized as a "bright giant" instead.
As with most such stars, Alpha Herculis is an irregular variable; its period is roughly 90 days.
One by one, I began to bag the targets in my double-star list: Alpha Ursae Majoris, Epsilon Bootes Alpha Canum Venaticorum, Gamma Leonis, Beta Cygni, Alpha Herculis, Epsilon Lyrae, Alpha Geminorum .