ABSTRACT
The most interesting star in Hercules is Alpha, often known by its proper name of Rasalgethi. It is rather divorced from the rest of the constellation, and is seen to the lower left in the photograph, to the right of the rather brighter Alpha Ophiuchi or Rasalhague. Alpha Herculis is a red supergiant. Alpha Herculis has an M-type spectrum; it is a huge star, with a relatively low surface temperature. In any case, Alpha Herculis is a beautiful sight when seen through an adequate telescope. Zeta Herculis is a fine binary; its double nature was discovered by William Herschel as long ago as 1782. The primary is a G-type sub-giant, 5 times as luminous as the Sun, while the K-type dwarf companion has about half the Sun’s luminosity.
